Add files using upload-large-folder tool
Browse filesThis view is limited to 50 files because it contains too many changes.
See raw diff
- .gitattributes +1 -2
- tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/__init__.cpython-312.pyc +0 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/conftest.cpython-312.pyc +0 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/convert.cpython-312.pyc +0 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/convert_matrix.cpython-312.pyc +0 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/exception.cpython-312.pyc +0 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/lazy_imports.cpython-312.pyc +0 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/relabel.cpython-312.pyc +0 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/__init__.py +133 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/__init__.py +26 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/clique.py +259 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/clustering_coefficient.py +71 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/connectivity.py +412 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/density.py +396 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/distance_measures.py +150 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/dominating_set.py +149 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/kcomponents.py +367 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/matching.py +44 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/maxcut.py +143 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/ramsey.py +53 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/steinertree.py +248 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/traveling_salesman.py +1508 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/treewidth.py +255 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/vertex_cover.py +83 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/__init__.py +5 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/connectivity.py +122 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/correlation.py +302 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/mixing.py +255 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/neighbor_degree.py +160 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/pairs.py +127 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/asteroidal.py +164 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/__init__.py +88 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/basic.py +322 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/centrality.py +290 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/cluster.py +289 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/covering.py +57 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/edgelist.py +360 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/extendability.py +105 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/generators.py +603 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/boundary.py +168 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bridges.py +205 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/broadcasting.py +155 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/chains.py +172 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/chordal.py +443 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/clique.py +757 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/cluster.py +658 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/communicability_alg.py +163 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/core.py +588 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/covering.py +142 -0
- tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/cuts.py +398 -0
.gitattributes
CHANGED
|
@@ -4023,5 +4023,4 @@ tool_server/.venv/lib/python3.12/site-packages/setuptools/command/__pycache__/ea
|
|
| 4023 |
tool_server/.venv/lib/python3.12/site-packages/setuptools/config/_validate_pyproject/__pycache__/fastjsonschema_validations.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
| 4024 |
tool_server/.venv/lib/python3.12/site-packages/regex/__pycache__/_regex_core.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
| 4025 |
tool_server/.venv/lib/python3.12/site-packages/regex/__pycache__/test_regex.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
| 4026 |
-
tool_server/.venv/lib/python3.12/site-packages/
|
| 4027 |
-
tool_server/.venv/lib/python3.12/site-packages/pygments/lexers/__pycache__/lisp.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
|
|
|
| 4023 |
tool_server/.venv/lib/python3.12/site-packages/setuptools/config/_validate_pyproject/__pycache__/fastjsonschema_validations.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
| 4024 |
tool_server/.venv/lib/python3.12/site-packages/regex/__pycache__/_regex_core.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
| 4025 |
tool_server/.venv/lib/python3.12/site-packages/regex/__pycache__/test_regex.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
| 4026 |
+
tool_server/.venv/lib/python3.12/site-packages/psutil/tests/__pycache__/test_linux.cpython-312.pyc filter=lfs diff=lfs merge=lfs -text
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/__init__.cpython-312.pyc
ADDED
|
Binary file (1.47 kB). View file
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/conftest.cpython-312.pyc
ADDED
|
Binary file (8.42 kB). View file
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/convert.cpython-312.pyc
ADDED
|
Binary file (18.9 kB). View file
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/convert_matrix.cpython-312.pyc
ADDED
|
Binary file (50.8 kB). View file
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/exception.cpython-312.pyc
ADDED
|
Binary file (5.39 kB). View file
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/lazy_imports.cpython-312.pyc
ADDED
|
Binary file (7.33 kB). View file
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/__pycache__/relabel.cpython-312.pyc
ADDED
|
Binary file (13.3 kB). View file
|
|
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/__init__.py
ADDED
|
@@ -0,0 +1,133 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
from networkx.algorithms.assortativity import *
|
| 2 |
+
from networkx.algorithms.asteroidal import *
|
| 3 |
+
from networkx.algorithms.boundary import *
|
| 4 |
+
from networkx.algorithms.broadcasting import *
|
| 5 |
+
from networkx.algorithms.bridges import *
|
| 6 |
+
from networkx.algorithms.chains import *
|
| 7 |
+
from networkx.algorithms.centrality import *
|
| 8 |
+
from networkx.algorithms.chordal import *
|
| 9 |
+
from networkx.algorithms.cluster import *
|
| 10 |
+
from networkx.algorithms.clique import *
|
| 11 |
+
from networkx.algorithms.communicability_alg import *
|
| 12 |
+
from networkx.algorithms.components import *
|
| 13 |
+
from networkx.algorithms.coloring import *
|
| 14 |
+
from networkx.algorithms.core import *
|
| 15 |
+
from networkx.algorithms.covering import *
|
| 16 |
+
from networkx.algorithms.cycles import *
|
| 17 |
+
from networkx.algorithms.cuts import *
|
| 18 |
+
from networkx.algorithms.d_separation import *
|
| 19 |
+
from networkx.algorithms.dag import *
|
| 20 |
+
from networkx.algorithms.distance_measures import *
|
| 21 |
+
from networkx.algorithms.distance_regular import *
|
| 22 |
+
from networkx.algorithms.dominance import *
|
| 23 |
+
from networkx.algorithms.dominating import *
|
| 24 |
+
from networkx.algorithms.efficiency_measures import *
|
| 25 |
+
from networkx.algorithms.euler import *
|
| 26 |
+
from networkx.algorithms.graphical import *
|
| 27 |
+
from networkx.algorithms.hierarchy import *
|
| 28 |
+
from networkx.algorithms.hybrid import *
|
| 29 |
+
from networkx.algorithms.link_analysis import *
|
| 30 |
+
from networkx.algorithms.link_prediction import *
|
| 31 |
+
from networkx.algorithms.lowest_common_ancestors import *
|
| 32 |
+
from networkx.algorithms.isolate import *
|
| 33 |
+
from networkx.algorithms.matching import *
|
| 34 |
+
from networkx.algorithms.minors import *
|
| 35 |
+
from networkx.algorithms.mis import *
|
| 36 |
+
from networkx.algorithms.moral import *
|
| 37 |
+
from networkx.algorithms.non_randomness import *
|
| 38 |
+
from networkx.algorithms.operators import *
|
| 39 |
+
from networkx.algorithms.planarity import *
|
| 40 |
+
from networkx.algorithms.planar_drawing import *
|
| 41 |
+
from networkx.algorithms.polynomials import *
|
| 42 |
+
from networkx.algorithms.reciprocity import *
|
| 43 |
+
from networkx.algorithms.regular import *
|
| 44 |
+
from networkx.algorithms.richclub import *
|
| 45 |
+
from networkx.algorithms.shortest_paths import *
|
| 46 |
+
from networkx.algorithms.similarity import *
|
| 47 |
+
from networkx.algorithms.graph_hashing import *
|
| 48 |
+
from networkx.algorithms.simple_paths import *
|
| 49 |
+
from networkx.algorithms.smallworld import *
|
| 50 |
+
from networkx.algorithms.smetric import *
|
| 51 |
+
from networkx.algorithms.structuralholes import *
|
| 52 |
+
from networkx.algorithms.sparsifiers import *
|
| 53 |
+
from networkx.algorithms.summarization import *
|
| 54 |
+
from networkx.algorithms.swap import *
|
| 55 |
+
from networkx.algorithms.time_dependent import *
|
| 56 |
+
from networkx.algorithms.traversal import *
|
| 57 |
+
from networkx.algorithms.triads import *
|
| 58 |
+
from networkx.algorithms.vitality import *
|
| 59 |
+
from networkx.algorithms.voronoi import *
|
| 60 |
+
from networkx.algorithms.walks import *
|
| 61 |
+
from networkx.algorithms.wiener import *
|
| 62 |
+
|
| 63 |
+
# Make certain subpackages available to the user as direct imports from
|
| 64 |
+
# the `networkx` namespace.
|
| 65 |
+
from networkx.algorithms import approximation
|
| 66 |
+
from networkx.algorithms import assortativity
|
| 67 |
+
from networkx.algorithms import bipartite
|
| 68 |
+
from networkx.algorithms import node_classification
|
| 69 |
+
from networkx.algorithms import centrality
|
| 70 |
+
from networkx.algorithms import chordal
|
| 71 |
+
from networkx.algorithms import cluster
|
| 72 |
+
from networkx.algorithms import clique
|
| 73 |
+
from networkx.algorithms import components
|
| 74 |
+
from networkx.algorithms import connectivity
|
| 75 |
+
from networkx.algorithms import community
|
| 76 |
+
from networkx.algorithms import coloring
|
| 77 |
+
from networkx.algorithms import flow
|
| 78 |
+
from networkx.algorithms import isomorphism
|
| 79 |
+
from networkx.algorithms import link_analysis
|
| 80 |
+
from networkx.algorithms import lowest_common_ancestors
|
| 81 |
+
from networkx.algorithms import operators
|
| 82 |
+
from networkx.algorithms import shortest_paths
|
| 83 |
+
from networkx.algorithms import tournament
|
| 84 |
+
from networkx.algorithms import traversal
|
| 85 |
+
from networkx.algorithms import tree
|
| 86 |
+
|
| 87 |
+
# Make certain functions from some of the previous subpackages available
|
| 88 |
+
# to the user as direct imports from the `networkx` namespace.
|
| 89 |
+
from networkx.algorithms.bipartite import complete_bipartite_graph
|
| 90 |
+
from networkx.algorithms.bipartite import is_bipartite
|
| 91 |
+
from networkx.algorithms.bipartite import projected_graph
|
| 92 |
+
from networkx.algorithms.connectivity import all_pairs_node_connectivity
|
| 93 |
+
from networkx.algorithms.connectivity import all_node_cuts
|
| 94 |
+
from networkx.algorithms.connectivity import average_node_connectivity
|
| 95 |
+
from networkx.algorithms.connectivity import edge_connectivity
|
| 96 |
+
from networkx.algorithms.connectivity import edge_disjoint_paths
|
| 97 |
+
from networkx.algorithms.connectivity import k_components
|
| 98 |
+
from networkx.algorithms.connectivity import k_edge_components
|
| 99 |
+
from networkx.algorithms.connectivity import k_edge_subgraphs
|
| 100 |
+
from networkx.algorithms.connectivity import k_edge_augmentation
|
| 101 |
+
from networkx.algorithms.connectivity import is_k_edge_connected
|
| 102 |
+
from networkx.algorithms.connectivity import minimum_edge_cut
|
| 103 |
+
from networkx.algorithms.connectivity import minimum_node_cut
|
| 104 |
+
from networkx.algorithms.connectivity import node_connectivity
|
| 105 |
+
from networkx.algorithms.connectivity import node_disjoint_paths
|
| 106 |
+
from networkx.algorithms.connectivity import stoer_wagner
|
| 107 |
+
from networkx.algorithms.flow import capacity_scaling
|
| 108 |
+
from networkx.algorithms.flow import cost_of_flow
|
| 109 |
+
from networkx.algorithms.flow import gomory_hu_tree
|
| 110 |
+
from networkx.algorithms.flow import max_flow_min_cost
|
| 111 |
+
from networkx.algorithms.flow import maximum_flow
|
| 112 |
+
from networkx.algorithms.flow import maximum_flow_value
|
| 113 |
+
from networkx.algorithms.flow import min_cost_flow
|
| 114 |
+
from networkx.algorithms.flow import min_cost_flow_cost
|
| 115 |
+
from networkx.algorithms.flow import minimum_cut
|
| 116 |
+
from networkx.algorithms.flow import minimum_cut_value
|
| 117 |
+
from networkx.algorithms.flow import network_simplex
|
| 118 |
+
from networkx.algorithms.isomorphism import could_be_isomorphic
|
| 119 |
+
from networkx.algorithms.isomorphism import fast_could_be_isomorphic
|
| 120 |
+
from networkx.algorithms.isomorphism import faster_could_be_isomorphic
|
| 121 |
+
from networkx.algorithms.isomorphism import is_isomorphic
|
| 122 |
+
from networkx.algorithms.isomorphism.vf2pp import *
|
| 123 |
+
from networkx.algorithms.tree.branchings import maximum_branching
|
| 124 |
+
from networkx.algorithms.tree.branchings import maximum_spanning_arborescence
|
| 125 |
+
from networkx.algorithms.tree.branchings import minimum_branching
|
| 126 |
+
from networkx.algorithms.tree.branchings import minimum_spanning_arborescence
|
| 127 |
+
from networkx.algorithms.tree.branchings import ArborescenceIterator
|
| 128 |
+
from networkx.algorithms.tree.coding import *
|
| 129 |
+
from networkx.algorithms.tree.decomposition import *
|
| 130 |
+
from networkx.algorithms.tree.mst import *
|
| 131 |
+
from networkx.algorithms.tree.operations import *
|
| 132 |
+
from networkx.algorithms.tree.recognition import *
|
| 133 |
+
from networkx.algorithms.tournament import is_tournament
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/__init__.py
ADDED
|
@@ -0,0 +1,26 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Approximations of graph properties and Heuristic methods for optimization.
|
| 2 |
+
|
| 3 |
+
The functions in this class are not imported into the top-level ``networkx``
|
| 4 |
+
namespace so the easiest way to use them is with::
|
| 5 |
+
|
| 6 |
+
>>> from networkx.algorithms import approximation
|
| 7 |
+
|
| 8 |
+
Another option is to import the specific function with
|
| 9 |
+
``from networkx.algorithms.approximation import function_name``.
|
| 10 |
+
|
| 11 |
+
"""
|
| 12 |
+
|
| 13 |
+
from networkx.algorithms.approximation.clustering_coefficient import *
|
| 14 |
+
from networkx.algorithms.approximation.clique import *
|
| 15 |
+
from networkx.algorithms.approximation.connectivity import *
|
| 16 |
+
from networkx.algorithms.approximation.distance_measures import *
|
| 17 |
+
from networkx.algorithms.approximation.dominating_set import *
|
| 18 |
+
from networkx.algorithms.approximation.kcomponents import *
|
| 19 |
+
from networkx.algorithms.approximation.matching import *
|
| 20 |
+
from networkx.algorithms.approximation.ramsey import *
|
| 21 |
+
from networkx.algorithms.approximation.steinertree import *
|
| 22 |
+
from networkx.algorithms.approximation.traveling_salesman import *
|
| 23 |
+
from networkx.algorithms.approximation.treewidth import *
|
| 24 |
+
from networkx.algorithms.approximation.vertex_cover import *
|
| 25 |
+
from networkx.algorithms.approximation.maxcut import *
|
| 26 |
+
from networkx.algorithms.approximation.density import *
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/clique.py
ADDED
|
@@ -0,0 +1,259 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for computing large cliques and maximum independent sets."""
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
from networkx.algorithms.approximation import ramsey
|
| 5 |
+
from networkx.utils import not_implemented_for
|
| 6 |
+
|
| 7 |
+
__all__ = [
|
| 8 |
+
"clique_removal",
|
| 9 |
+
"max_clique",
|
| 10 |
+
"large_clique_size",
|
| 11 |
+
"maximum_independent_set",
|
| 12 |
+
]
|
| 13 |
+
|
| 14 |
+
|
| 15 |
+
@not_implemented_for("directed")
|
| 16 |
+
@not_implemented_for("multigraph")
|
| 17 |
+
@nx._dispatchable
|
| 18 |
+
def maximum_independent_set(G):
|
| 19 |
+
"""Returns an approximate maximum independent set.
|
| 20 |
+
|
| 21 |
+
Independent set or stable set is a set of vertices in a graph, no two of
|
| 22 |
+
which are adjacent. That is, it is a set I of vertices such that for every
|
| 23 |
+
two vertices in I, there is no edge connecting the two. Equivalently, each
|
| 24 |
+
edge in the graph has at most one endpoint in I. The size of an independent
|
| 25 |
+
set is the number of vertices it contains [1]_.
|
| 26 |
+
|
| 27 |
+
A maximum independent set is a largest independent set for a given graph G
|
| 28 |
+
and its size is denoted $\\alpha(G)$. The problem of finding such a set is called
|
| 29 |
+
the maximum independent set problem and is an NP-hard optimization problem.
|
| 30 |
+
As such, it is unlikely that there exists an efficient algorithm for finding
|
| 31 |
+
a maximum independent set of a graph.
|
| 32 |
+
|
| 33 |
+
The Independent Set algorithm is based on [2]_.
|
| 34 |
+
|
| 35 |
+
Parameters
|
| 36 |
+
----------
|
| 37 |
+
G : NetworkX graph
|
| 38 |
+
Undirected graph
|
| 39 |
+
|
| 40 |
+
Returns
|
| 41 |
+
-------
|
| 42 |
+
iset : Set
|
| 43 |
+
The apx-maximum independent set
|
| 44 |
+
|
| 45 |
+
Examples
|
| 46 |
+
--------
|
| 47 |
+
>>> G = nx.path_graph(10)
|
| 48 |
+
>>> nx.approximation.maximum_independent_set(G)
|
| 49 |
+
{0, 2, 4, 6, 9}
|
| 50 |
+
|
| 51 |
+
Raises
|
| 52 |
+
------
|
| 53 |
+
NetworkXNotImplemented
|
| 54 |
+
If the graph is directed or is a multigraph.
|
| 55 |
+
|
| 56 |
+
Notes
|
| 57 |
+
-----
|
| 58 |
+
Finds the $O(|V|/(log|V|)^2)$ apx of independent set in the worst case.
|
| 59 |
+
|
| 60 |
+
References
|
| 61 |
+
----------
|
| 62 |
+
.. [1] `Wikipedia: Independent set
|
| 63 |
+
<https://en.wikipedia.org/wiki/Independent_set_(graph_theory)>`_
|
| 64 |
+
.. [2] Boppana, R., & Halldórsson, M. M. (1992).
|
| 65 |
+
Approximating maximum independent sets by excluding subgraphs.
|
| 66 |
+
BIT Numerical Mathematics, 32(2), 180–196. Springer.
|
| 67 |
+
"""
|
| 68 |
+
iset, _ = clique_removal(G)
|
| 69 |
+
return iset
|
| 70 |
+
|
| 71 |
+
|
| 72 |
+
@not_implemented_for("directed")
|
| 73 |
+
@not_implemented_for("multigraph")
|
| 74 |
+
@nx._dispatchable
|
| 75 |
+
def max_clique(G):
|
| 76 |
+
r"""Find the Maximum Clique
|
| 77 |
+
|
| 78 |
+
Finds the $O(|V|/(log|V|)^2)$ apx of maximum clique/independent set
|
| 79 |
+
in the worst case.
|
| 80 |
+
|
| 81 |
+
Parameters
|
| 82 |
+
----------
|
| 83 |
+
G : NetworkX graph
|
| 84 |
+
Undirected graph
|
| 85 |
+
|
| 86 |
+
Returns
|
| 87 |
+
-------
|
| 88 |
+
clique : set
|
| 89 |
+
The apx-maximum clique of the graph
|
| 90 |
+
|
| 91 |
+
Examples
|
| 92 |
+
--------
|
| 93 |
+
>>> G = nx.path_graph(10)
|
| 94 |
+
>>> nx.approximation.max_clique(G)
|
| 95 |
+
{8, 9}
|
| 96 |
+
|
| 97 |
+
Raises
|
| 98 |
+
------
|
| 99 |
+
NetworkXNotImplemented
|
| 100 |
+
If the graph is directed or is a multigraph.
|
| 101 |
+
|
| 102 |
+
Notes
|
| 103 |
+
-----
|
| 104 |
+
A clique in an undirected graph G = (V, E) is a subset of the vertex set
|
| 105 |
+
`C \subseteq V` such that for every two vertices in C there exists an edge
|
| 106 |
+
connecting the two. This is equivalent to saying that the subgraph
|
| 107 |
+
induced by C is complete (in some cases, the term clique may also refer
|
| 108 |
+
to the subgraph).
|
| 109 |
+
|
| 110 |
+
A maximum clique is a clique of the largest possible size in a given graph.
|
| 111 |
+
The clique number `\omega(G)` of a graph G is the number of
|
| 112 |
+
vertices in a maximum clique in G. The intersection number of
|
| 113 |
+
G is the smallest number of cliques that together cover all edges of G.
|
| 114 |
+
|
| 115 |
+
https://en.wikipedia.org/wiki/Maximum_clique
|
| 116 |
+
|
| 117 |
+
References
|
| 118 |
+
----------
|
| 119 |
+
.. [1] Boppana, R., & Halldórsson, M. M. (1992).
|
| 120 |
+
Approximating maximum independent sets by excluding subgraphs.
|
| 121 |
+
BIT Numerical Mathematics, 32(2), 180–196. Springer.
|
| 122 |
+
doi:10.1007/BF01994876
|
| 123 |
+
"""
|
| 124 |
+
# finding the maximum clique in a graph is equivalent to finding
|
| 125 |
+
# the independent set in the complementary graph
|
| 126 |
+
cgraph = nx.complement(G)
|
| 127 |
+
iset, _ = clique_removal(cgraph)
|
| 128 |
+
return iset
|
| 129 |
+
|
| 130 |
+
|
| 131 |
+
@not_implemented_for("directed")
|
| 132 |
+
@not_implemented_for("multigraph")
|
| 133 |
+
@nx._dispatchable
|
| 134 |
+
def clique_removal(G):
|
| 135 |
+
r"""Repeatedly remove cliques from the graph.
|
| 136 |
+
|
| 137 |
+
Results in a $O(|V|/(\log |V|)^2)$ approximation of maximum clique
|
| 138 |
+
and independent set. Returns the largest independent set found, along
|
| 139 |
+
with found maximal cliques.
|
| 140 |
+
|
| 141 |
+
Parameters
|
| 142 |
+
----------
|
| 143 |
+
G : NetworkX graph
|
| 144 |
+
Undirected graph
|
| 145 |
+
|
| 146 |
+
Returns
|
| 147 |
+
-------
|
| 148 |
+
max_ind_cliques : (set, list) tuple
|
| 149 |
+
2-tuple of Maximal Independent Set and list of maximal cliques (sets).
|
| 150 |
+
|
| 151 |
+
Examples
|
| 152 |
+
--------
|
| 153 |
+
>>> G = nx.path_graph(10)
|
| 154 |
+
>>> nx.approximation.clique_removal(G)
|
| 155 |
+
({0, 2, 4, 6, 9}, [{0, 1}, {2, 3}, {4, 5}, {6, 7}, {8, 9}])
|
| 156 |
+
|
| 157 |
+
Raises
|
| 158 |
+
------
|
| 159 |
+
NetworkXNotImplemented
|
| 160 |
+
If the graph is directed or is a multigraph.
|
| 161 |
+
|
| 162 |
+
References
|
| 163 |
+
----------
|
| 164 |
+
.. [1] Boppana, R., & Halldórsson, M. M. (1992).
|
| 165 |
+
Approximating maximum independent sets by excluding subgraphs.
|
| 166 |
+
BIT Numerical Mathematics, 32(2), 180–196. Springer.
|
| 167 |
+
"""
|
| 168 |
+
graph = G.copy()
|
| 169 |
+
c_i, i_i = ramsey.ramsey_R2(graph)
|
| 170 |
+
cliques = [c_i]
|
| 171 |
+
isets = [i_i]
|
| 172 |
+
while graph:
|
| 173 |
+
graph.remove_nodes_from(c_i)
|
| 174 |
+
c_i, i_i = ramsey.ramsey_R2(graph)
|
| 175 |
+
if c_i:
|
| 176 |
+
cliques.append(c_i)
|
| 177 |
+
if i_i:
|
| 178 |
+
isets.append(i_i)
|
| 179 |
+
# Determine the largest independent set as measured by cardinality.
|
| 180 |
+
maxiset = max(isets, key=len)
|
| 181 |
+
return maxiset, cliques
|
| 182 |
+
|
| 183 |
+
|
| 184 |
+
@not_implemented_for("directed")
|
| 185 |
+
@not_implemented_for("multigraph")
|
| 186 |
+
@nx._dispatchable
|
| 187 |
+
def large_clique_size(G):
|
| 188 |
+
"""Find the size of a large clique in a graph.
|
| 189 |
+
|
| 190 |
+
A *clique* is a subset of nodes in which each pair of nodes is
|
| 191 |
+
adjacent. This function is a heuristic for finding the size of a
|
| 192 |
+
large clique in the graph.
|
| 193 |
+
|
| 194 |
+
Parameters
|
| 195 |
+
----------
|
| 196 |
+
G : NetworkX graph
|
| 197 |
+
|
| 198 |
+
Returns
|
| 199 |
+
-------
|
| 200 |
+
k: integer
|
| 201 |
+
The size of a large clique in the graph.
|
| 202 |
+
|
| 203 |
+
Examples
|
| 204 |
+
--------
|
| 205 |
+
>>> G = nx.path_graph(10)
|
| 206 |
+
>>> nx.approximation.large_clique_size(G)
|
| 207 |
+
2
|
| 208 |
+
|
| 209 |
+
Raises
|
| 210 |
+
------
|
| 211 |
+
NetworkXNotImplemented
|
| 212 |
+
If the graph is directed or is a multigraph.
|
| 213 |
+
|
| 214 |
+
Notes
|
| 215 |
+
-----
|
| 216 |
+
This implementation is from [1]_. Its worst case time complexity is
|
| 217 |
+
:math:`O(n d^2)`, where *n* is the number of nodes in the graph and
|
| 218 |
+
*d* is the maximum degree.
|
| 219 |
+
|
| 220 |
+
This function is a heuristic, which means it may work well in
|
| 221 |
+
practice, but there is no rigorous mathematical guarantee on the
|
| 222 |
+
ratio between the returned number and the actual largest clique size
|
| 223 |
+
in the graph.
|
| 224 |
+
|
| 225 |
+
References
|
| 226 |
+
----------
|
| 227 |
+
.. [1] Pattabiraman, Bharath, et al.
|
| 228 |
+
"Fast Algorithms for the Maximum Clique Problem on Massive Graphs
|
| 229 |
+
with Applications to Overlapping Community Detection."
|
| 230 |
+
*Internet Mathematics* 11.4-5 (2015): 421--448.
|
| 231 |
+
<https://doi.org/10.1080/15427951.2014.986778>
|
| 232 |
+
|
| 233 |
+
See also
|
| 234 |
+
--------
|
| 235 |
+
|
| 236 |
+
:func:`networkx.algorithms.approximation.clique.max_clique`
|
| 237 |
+
A function that returns an approximate maximum clique with a
|
| 238 |
+
guarantee on the approximation ratio.
|
| 239 |
+
|
| 240 |
+
:mod:`networkx.algorithms.clique`
|
| 241 |
+
Functions for finding the exact maximum clique in a graph.
|
| 242 |
+
|
| 243 |
+
"""
|
| 244 |
+
degrees = G.degree
|
| 245 |
+
|
| 246 |
+
def _clique_heuristic(G, U, size, best_size):
|
| 247 |
+
if not U:
|
| 248 |
+
return max(best_size, size)
|
| 249 |
+
u = max(U, key=degrees)
|
| 250 |
+
U.remove(u)
|
| 251 |
+
N_prime = {v for v in G[u] if degrees[v] >= best_size}
|
| 252 |
+
return _clique_heuristic(G, U & N_prime, size + 1, best_size)
|
| 253 |
+
|
| 254 |
+
best_size = 0
|
| 255 |
+
nodes = (u for u in G if degrees[u] >= best_size)
|
| 256 |
+
for u in nodes:
|
| 257 |
+
neighbors = {v for v in G[u] if degrees[v] >= best_size}
|
| 258 |
+
best_size = _clique_heuristic(G, neighbors, 1, best_size)
|
| 259 |
+
return best_size
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/clustering_coefficient.py
ADDED
|
@@ -0,0 +1,71 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
import networkx as nx
|
| 2 |
+
from networkx.utils import not_implemented_for, py_random_state
|
| 3 |
+
|
| 4 |
+
__all__ = ["average_clustering"]
|
| 5 |
+
|
| 6 |
+
|
| 7 |
+
@not_implemented_for("directed")
|
| 8 |
+
@py_random_state(2)
|
| 9 |
+
@nx._dispatchable(name="approximate_average_clustering")
|
| 10 |
+
def average_clustering(G, trials=1000, seed=None):
|
| 11 |
+
r"""Estimates the average clustering coefficient of G.
|
| 12 |
+
|
| 13 |
+
The local clustering of each node in `G` is the fraction of triangles
|
| 14 |
+
that actually exist over all possible triangles in its neighborhood.
|
| 15 |
+
The average clustering coefficient of a graph `G` is the mean of
|
| 16 |
+
local clusterings.
|
| 17 |
+
|
| 18 |
+
This function finds an approximate average clustering coefficient
|
| 19 |
+
for G by repeating `n` times (defined in `trials`) the following
|
| 20 |
+
experiment: choose a node at random, choose two of its neighbors
|
| 21 |
+
at random, and check if they are connected. The approximate
|
| 22 |
+
coefficient is the fraction of triangles found over the number
|
| 23 |
+
of trials [1]_.
|
| 24 |
+
|
| 25 |
+
Parameters
|
| 26 |
+
----------
|
| 27 |
+
G : NetworkX graph
|
| 28 |
+
|
| 29 |
+
trials : integer
|
| 30 |
+
Number of trials to perform (default 1000).
|
| 31 |
+
|
| 32 |
+
seed : integer, random_state, or None (default)
|
| 33 |
+
Indicator of random number generation state.
|
| 34 |
+
See :ref:`Randomness<randomness>`.
|
| 35 |
+
|
| 36 |
+
Returns
|
| 37 |
+
-------
|
| 38 |
+
c : float
|
| 39 |
+
Approximated average clustering coefficient.
|
| 40 |
+
|
| 41 |
+
Examples
|
| 42 |
+
--------
|
| 43 |
+
>>> from networkx.algorithms import approximation
|
| 44 |
+
>>> G = nx.erdos_renyi_graph(10, 0.2, seed=10)
|
| 45 |
+
>>> approximation.average_clustering(G, trials=1000, seed=10)
|
| 46 |
+
0.214
|
| 47 |
+
|
| 48 |
+
Raises
|
| 49 |
+
------
|
| 50 |
+
NetworkXNotImplemented
|
| 51 |
+
If G is directed.
|
| 52 |
+
|
| 53 |
+
References
|
| 54 |
+
----------
|
| 55 |
+
.. [1] Schank, Thomas, and Dorothea Wagner. Approximating clustering
|
| 56 |
+
coefficient and transitivity. Universität Karlsruhe, Fakultät für
|
| 57 |
+
Informatik, 2004.
|
| 58 |
+
https://doi.org/10.5445/IR/1000001239
|
| 59 |
+
|
| 60 |
+
"""
|
| 61 |
+
n = len(G)
|
| 62 |
+
triangles = 0
|
| 63 |
+
nodes = list(G)
|
| 64 |
+
for i in [int(seed.random() * n) for i in range(trials)]:
|
| 65 |
+
nbrs = list(G[nodes[i]])
|
| 66 |
+
if len(nbrs) < 2:
|
| 67 |
+
continue
|
| 68 |
+
u, v = seed.sample(nbrs, 2)
|
| 69 |
+
if u in G[v]:
|
| 70 |
+
triangles += 1
|
| 71 |
+
return triangles / trials
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/connectivity.py
ADDED
|
@@ -0,0 +1,412 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Fast approximation for node connectivity"""
|
| 2 |
+
|
| 3 |
+
import itertools
|
| 4 |
+
from operator import itemgetter
|
| 5 |
+
|
| 6 |
+
import networkx as nx
|
| 7 |
+
|
| 8 |
+
__all__ = [
|
| 9 |
+
"local_node_connectivity",
|
| 10 |
+
"node_connectivity",
|
| 11 |
+
"all_pairs_node_connectivity",
|
| 12 |
+
]
|
| 13 |
+
|
| 14 |
+
|
| 15 |
+
@nx._dispatchable(name="approximate_local_node_connectivity")
|
| 16 |
+
def local_node_connectivity(G, source, target, cutoff=None):
|
| 17 |
+
"""Compute node connectivity between source and target.
|
| 18 |
+
|
| 19 |
+
Pairwise or local node connectivity between two distinct and nonadjacent
|
| 20 |
+
nodes is the minimum number of nodes that must be removed (minimum
|
| 21 |
+
separating cutset) to disconnect them. By Menger's theorem, this is equal
|
| 22 |
+
to the number of node independent paths (paths that share no nodes other
|
| 23 |
+
than source and target). Which is what we compute in this function.
|
| 24 |
+
|
| 25 |
+
This algorithm is a fast approximation that gives an strict lower
|
| 26 |
+
bound on the actual number of node independent paths between two nodes [1]_.
|
| 27 |
+
It works for both directed and undirected graphs.
|
| 28 |
+
|
| 29 |
+
Parameters
|
| 30 |
+
----------
|
| 31 |
+
|
| 32 |
+
G : NetworkX graph
|
| 33 |
+
|
| 34 |
+
source : node
|
| 35 |
+
Starting node for node connectivity
|
| 36 |
+
|
| 37 |
+
target : node
|
| 38 |
+
Ending node for node connectivity
|
| 39 |
+
|
| 40 |
+
cutoff : integer
|
| 41 |
+
Maximum node connectivity to consider. If None, the minimum degree
|
| 42 |
+
of source or target is used as a cutoff. Default value None.
|
| 43 |
+
|
| 44 |
+
Returns
|
| 45 |
+
-------
|
| 46 |
+
k: integer
|
| 47 |
+
pairwise node connectivity
|
| 48 |
+
|
| 49 |
+
Examples
|
| 50 |
+
--------
|
| 51 |
+
>>> # Platonic octahedral graph has node connectivity 4
|
| 52 |
+
>>> # for each non adjacent node pair
|
| 53 |
+
>>> from networkx.algorithms import approximation as approx
|
| 54 |
+
>>> G = nx.octahedral_graph()
|
| 55 |
+
>>> approx.local_node_connectivity(G, 0, 5)
|
| 56 |
+
4
|
| 57 |
+
|
| 58 |
+
Notes
|
| 59 |
+
-----
|
| 60 |
+
This algorithm [1]_ finds node independents paths between two nodes by
|
| 61 |
+
computing their shortest path using BFS, marking the nodes of the path
|
| 62 |
+
found as 'used' and then searching other shortest paths excluding the
|
| 63 |
+
nodes marked as used until no more paths exist. It is not exact because
|
| 64 |
+
a shortest path could use nodes that, if the path were longer, may belong
|
| 65 |
+
to two different node independent paths. Thus it only guarantees an
|
| 66 |
+
strict lower bound on node connectivity.
|
| 67 |
+
|
| 68 |
+
Note that the authors propose a further refinement, losing accuracy and
|
| 69 |
+
gaining speed, which is not implemented yet.
|
| 70 |
+
|
| 71 |
+
See also
|
| 72 |
+
--------
|
| 73 |
+
all_pairs_node_connectivity
|
| 74 |
+
node_connectivity
|
| 75 |
+
|
| 76 |
+
References
|
| 77 |
+
----------
|
| 78 |
+
.. [1] White, Douglas R., and Mark Newman. 2001 A Fast Algorithm for
|
| 79 |
+
Node-Independent Paths. Santa Fe Institute Working Paper #01-07-035
|
| 80 |
+
http://eclectic.ss.uci.edu/~drwhite/working.pdf
|
| 81 |
+
|
| 82 |
+
"""
|
| 83 |
+
if target == source:
|
| 84 |
+
raise nx.NetworkXError("source and target have to be different nodes.")
|
| 85 |
+
|
| 86 |
+
# Maximum possible node independent paths
|
| 87 |
+
if G.is_directed():
|
| 88 |
+
possible = min(G.out_degree(source), G.in_degree(target))
|
| 89 |
+
else:
|
| 90 |
+
possible = min(G.degree(source), G.degree(target))
|
| 91 |
+
|
| 92 |
+
K = 0
|
| 93 |
+
if not possible:
|
| 94 |
+
return K
|
| 95 |
+
|
| 96 |
+
if cutoff is None:
|
| 97 |
+
cutoff = float("inf")
|
| 98 |
+
|
| 99 |
+
exclude = set()
|
| 100 |
+
for i in range(min(possible, cutoff)):
|
| 101 |
+
try:
|
| 102 |
+
path = _bidirectional_shortest_path(G, source, target, exclude)
|
| 103 |
+
exclude.update(set(path))
|
| 104 |
+
K += 1
|
| 105 |
+
except nx.NetworkXNoPath:
|
| 106 |
+
break
|
| 107 |
+
|
| 108 |
+
return K
|
| 109 |
+
|
| 110 |
+
|
| 111 |
+
@nx._dispatchable(name="approximate_node_connectivity")
|
| 112 |
+
def node_connectivity(G, s=None, t=None):
|
| 113 |
+
r"""Returns an approximation for node connectivity for a graph or digraph G.
|
| 114 |
+
|
| 115 |
+
Node connectivity is equal to the minimum number of nodes that
|
| 116 |
+
must be removed to disconnect G or render it trivial. By Menger's theorem,
|
| 117 |
+
this is equal to the number of node independent paths (paths that
|
| 118 |
+
share no nodes other than source and target).
|
| 119 |
+
|
| 120 |
+
If source and target nodes are provided, this function returns the
|
| 121 |
+
local node connectivity: the minimum number of nodes that must be
|
| 122 |
+
removed to break all paths from source to target in G.
|
| 123 |
+
|
| 124 |
+
This algorithm is based on a fast approximation that gives an strict lower
|
| 125 |
+
bound on the actual number of node independent paths between two nodes [1]_.
|
| 126 |
+
It works for both directed and undirected graphs.
|
| 127 |
+
|
| 128 |
+
Parameters
|
| 129 |
+
----------
|
| 130 |
+
G : NetworkX graph
|
| 131 |
+
Undirected graph
|
| 132 |
+
|
| 133 |
+
s : node
|
| 134 |
+
Source node. Optional. Default value: None.
|
| 135 |
+
|
| 136 |
+
t : node
|
| 137 |
+
Target node. Optional. Default value: None.
|
| 138 |
+
|
| 139 |
+
Returns
|
| 140 |
+
-------
|
| 141 |
+
K : integer
|
| 142 |
+
Node connectivity of G, or local node connectivity if source
|
| 143 |
+
and target are provided.
|
| 144 |
+
|
| 145 |
+
Examples
|
| 146 |
+
--------
|
| 147 |
+
>>> # Platonic octahedral graph is 4-node-connected
|
| 148 |
+
>>> from networkx.algorithms import approximation as approx
|
| 149 |
+
>>> G = nx.octahedral_graph()
|
| 150 |
+
>>> approx.node_connectivity(G)
|
| 151 |
+
4
|
| 152 |
+
|
| 153 |
+
Notes
|
| 154 |
+
-----
|
| 155 |
+
This algorithm [1]_ finds node independents paths between two nodes by
|
| 156 |
+
computing their shortest path using BFS, marking the nodes of the path
|
| 157 |
+
found as 'used' and then searching other shortest paths excluding the
|
| 158 |
+
nodes marked as used until no more paths exist. It is not exact because
|
| 159 |
+
a shortest path could use nodes that, if the path were longer, may belong
|
| 160 |
+
to two different node independent paths. Thus it only guarantees an
|
| 161 |
+
strict lower bound on node connectivity.
|
| 162 |
+
|
| 163 |
+
See also
|
| 164 |
+
--------
|
| 165 |
+
all_pairs_node_connectivity
|
| 166 |
+
local_node_connectivity
|
| 167 |
+
|
| 168 |
+
References
|
| 169 |
+
----------
|
| 170 |
+
.. [1] White, Douglas R., and Mark Newman. 2001 A Fast Algorithm for
|
| 171 |
+
Node-Independent Paths. Santa Fe Institute Working Paper #01-07-035
|
| 172 |
+
http://eclectic.ss.uci.edu/~drwhite/working.pdf
|
| 173 |
+
|
| 174 |
+
"""
|
| 175 |
+
if (s is not None and t is None) or (s is None and t is not None):
|
| 176 |
+
raise nx.NetworkXError("Both source and target must be specified.")
|
| 177 |
+
|
| 178 |
+
# Local node connectivity
|
| 179 |
+
if s is not None and t is not None:
|
| 180 |
+
if s not in G:
|
| 181 |
+
raise nx.NetworkXError(f"node {s} not in graph")
|
| 182 |
+
if t not in G:
|
| 183 |
+
raise nx.NetworkXError(f"node {t} not in graph")
|
| 184 |
+
return local_node_connectivity(G, s, t)
|
| 185 |
+
|
| 186 |
+
# Global node connectivity
|
| 187 |
+
if G.is_directed():
|
| 188 |
+
connected_func = nx.is_weakly_connected
|
| 189 |
+
iter_func = itertools.permutations
|
| 190 |
+
|
| 191 |
+
def neighbors(v):
|
| 192 |
+
return itertools.chain(G.predecessors(v), G.successors(v))
|
| 193 |
+
|
| 194 |
+
else:
|
| 195 |
+
connected_func = nx.is_connected
|
| 196 |
+
iter_func = itertools.combinations
|
| 197 |
+
neighbors = G.neighbors
|
| 198 |
+
|
| 199 |
+
if not connected_func(G):
|
| 200 |
+
return 0
|
| 201 |
+
|
| 202 |
+
# Choose a node with minimum degree
|
| 203 |
+
v, minimum_degree = min(G.degree(), key=itemgetter(1))
|
| 204 |
+
# Node connectivity is bounded by minimum degree
|
| 205 |
+
K = minimum_degree
|
| 206 |
+
# compute local node connectivity with all non-neighbors nodes
|
| 207 |
+
# and store the minimum
|
| 208 |
+
for w in set(G) - set(neighbors(v)) - {v}:
|
| 209 |
+
K = min(K, local_node_connectivity(G, v, w, cutoff=K))
|
| 210 |
+
# Same for non adjacent pairs of neighbors of v
|
| 211 |
+
for x, y in iter_func(neighbors(v), 2):
|
| 212 |
+
if y not in G[x] and x != y:
|
| 213 |
+
K = min(K, local_node_connectivity(G, x, y, cutoff=K))
|
| 214 |
+
return K
|
| 215 |
+
|
| 216 |
+
|
| 217 |
+
@nx._dispatchable(name="approximate_all_pairs_node_connectivity")
|
| 218 |
+
def all_pairs_node_connectivity(G, nbunch=None, cutoff=None):
|
| 219 |
+
"""Compute node connectivity between all pairs of nodes.
|
| 220 |
+
|
| 221 |
+
Pairwise or local node connectivity between two distinct and nonadjacent
|
| 222 |
+
nodes is the minimum number of nodes that must be removed (minimum
|
| 223 |
+
separating cutset) to disconnect them. By Menger's theorem, this is equal
|
| 224 |
+
to the number of node independent paths (paths that share no nodes other
|
| 225 |
+
than source and target). Which is what we compute in this function.
|
| 226 |
+
|
| 227 |
+
This algorithm is a fast approximation that gives an strict lower
|
| 228 |
+
bound on the actual number of node independent paths between two nodes [1]_.
|
| 229 |
+
It works for both directed and undirected graphs.
|
| 230 |
+
|
| 231 |
+
|
| 232 |
+
Parameters
|
| 233 |
+
----------
|
| 234 |
+
G : NetworkX graph
|
| 235 |
+
|
| 236 |
+
nbunch: container
|
| 237 |
+
Container of nodes. If provided node connectivity will be computed
|
| 238 |
+
only over pairs of nodes in nbunch.
|
| 239 |
+
|
| 240 |
+
cutoff : integer
|
| 241 |
+
Maximum node connectivity to consider. If None, the minimum degree
|
| 242 |
+
of source or target is used as a cutoff in each pair of nodes.
|
| 243 |
+
Default value None.
|
| 244 |
+
|
| 245 |
+
Returns
|
| 246 |
+
-------
|
| 247 |
+
K : dictionary
|
| 248 |
+
Dictionary, keyed by source and target, of pairwise node connectivity
|
| 249 |
+
|
| 250 |
+
Examples
|
| 251 |
+
--------
|
| 252 |
+
A 3 node cycle with one extra node attached has connectivity 2 between all
|
| 253 |
+
nodes in the cycle and connectivity 1 between the extra node and the rest:
|
| 254 |
+
|
| 255 |
+
>>> G = nx.cycle_graph(3)
|
| 256 |
+
>>> G.add_edge(2, 3)
|
| 257 |
+
>>> import pprint # for nice dictionary formatting
|
| 258 |
+
>>> pprint.pprint(nx.all_pairs_node_connectivity(G))
|
| 259 |
+
{0: {1: 2, 2: 2, 3: 1},
|
| 260 |
+
1: {0: 2, 2: 2, 3: 1},
|
| 261 |
+
2: {0: 2, 1: 2, 3: 1},
|
| 262 |
+
3: {0: 1, 1: 1, 2: 1}}
|
| 263 |
+
|
| 264 |
+
See Also
|
| 265 |
+
--------
|
| 266 |
+
local_node_connectivity
|
| 267 |
+
node_connectivity
|
| 268 |
+
|
| 269 |
+
References
|
| 270 |
+
----------
|
| 271 |
+
.. [1] White, Douglas R., and Mark Newman. 2001 A Fast Algorithm for
|
| 272 |
+
Node-Independent Paths. Santa Fe Institute Working Paper #01-07-035
|
| 273 |
+
http://eclectic.ss.uci.edu/~drwhite/working.pdf
|
| 274 |
+
"""
|
| 275 |
+
if nbunch is None:
|
| 276 |
+
nbunch = G
|
| 277 |
+
else:
|
| 278 |
+
nbunch = set(nbunch)
|
| 279 |
+
|
| 280 |
+
directed = G.is_directed()
|
| 281 |
+
if directed:
|
| 282 |
+
iter_func = itertools.permutations
|
| 283 |
+
else:
|
| 284 |
+
iter_func = itertools.combinations
|
| 285 |
+
|
| 286 |
+
all_pairs = {n: {} for n in nbunch}
|
| 287 |
+
|
| 288 |
+
for u, v in iter_func(nbunch, 2):
|
| 289 |
+
k = local_node_connectivity(G, u, v, cutoff=cutoff)
|
| 290 |
+
all_pairs[u][v] = k
|
| 291 |
+
if not directed:
|
| 292 |
+
all_pairs[v][u] = k
|
| 293 |
+
|
| 294 |
+
return all_pairs
|
| 295 |
+
|
| 296 |
+
|
| 297 |
+
def _bidirectional_shortest_path(G, source, target, exclude):
|
| 298 |
+
"""Returns shortest path between source and target ignoring nodes in the
|
| 299 |
+
container 'exclude'.
|
| 300 |
+
|
| 301 |
+
Parameters
|
| 302 |
+
----------
|
| 303 |
+
|
| 304 |
+
G : NetworkX graph
|
| 305 |
+
|
| 306 |
+
source : node
|
| 307 |
+
Starting node for path
|
| 308 |
+
|
| 309 |
+
target : node
|
| 310 |
+
Ending node for path
|
| 311 |
+
|
| 312 |
+
exclude: container
|
| 313 |
+
Container for nodes to exclude from the search for shortest paths
|
| 314 |
+
|
| 315 |
+
Returns
|
| 316 |
+
-------
|
| 317 |
+
path: list
|
| 318 |
+
Shortest path between source and target ignoring nodes in 'exclude'
|
| 319 |
+
|
| 320 |
+
Raises
|
| 321 |
+
------
|
| 322 |
+
NetworkXNoPath
|
| 323 |
+
If there is no path or if nodes are adjacent and have only one path
|
| 324 |
+
between them
|
| 325 |
+
|
| 326 |
+
Notes
|
| 327 |
+
-----
|
| 328 |
+
This function and its helper are originally from
|
| 329 |
+
networkx.algorithms.shortest_paths.unweighted and are modified to
|
| 330 |
+
accept the extra parameter 'exclude', which is a container for nodes
|
| 331 |
+
already used in other paths that should be ignored.
|
| 332 |
+
|
| 333 |
+
References
|
| 334 |
+
----------
|
| 335 |
+
.. [1] White, Douglas R., and Mark Newman. 2001 A Fast Algorithm for
|
| 336 |
+
Node-Independent Paths. Santa Fe Institute Working Paper #01-07-035
|
| 337 |
+
http://eclectic.ss.uci.edu/~drwhite/working.pdf
|
| 338 |
+
|
| 339 |
+
"""
|
| 340 |
+
# call helper to do the real work
|
| 341 |
+
results = _bidirectional_pred_succ(G, source, target, exclude)
|
| 342 |
+
pred, succ, w = results
|
| 343 |
+
|
| 344 |
+
# build path from pred+w+succ
|
| 345 |
+
path = []
|
| 346 |
+
# from source to w
|
| 347 |
+
while w is not None:
|
| 348 |
+
path.append(w)
|
| 349 |
+
w = pred[w]
|
| 350 |
+
path.reverse()
|
| 351 |
+
# from w to target
|
| 352 |
+
w = succ[path[-1]]
|
| 353 |
+
while w is not None:
|
| 354 |
+
path.append(w)
|
| 355 |
+
w = succ[w]
|
| 356 |
+
|
| 357 |
+
return path
|
| 358 |
+
|
| 359 |
+
|
| 360 |
+
def _bidirectional_pred_succ(G, source, target, exclude):
|
| 361 |
+
# does BFS from both source and target and meets in the middle
|
| 362 |
+
# excludes nodes in the container "exclude" from the search
|
| 363 |
+
|
| 364 |
+
# handle either directed or undirected
|
| 365 |
+
if G.is_directed():
|
| 366 |
+
Gpred = G.predecessors
|
| 367 |
+
Gsucc = G.successors
|
| 368 |
+
else:
|
| 369 |
+
Gpred = G.neighbors
|
| 370 |
+
Gsucc = G.neighbors
|
| 371 |
+
|
| 372 |
+
# predecessor and successors in search
|
| 373 |
+
pred = {source: None}
|
| 374 |
+
succ = {target: None}
|
| 375 |
+
|
| 376 |
+
# initialize fringes, start with forward
|
| 377 |
+
forward_fringe = [source]
|
| 378 |
+
reverse_fringe = [target]
|
| 379 |
+
|
| 380 |
+
level = 0
|
| 381 |
+
|
| 382 |
+
while forward_fringe and reverse_fringe:
|
| 383 |
+
# Make sure that we iterate one step forward and one step backwards
|
| 384 |
+
# thus source and target will only trigger "found path" when they are
|
| 385 |
+
# adjacent and then they can be safely included in the container 'exclude'
|
| 386 |
+
level += 1
|
| 387 |
+
if level % 2 != 0:
|
| 388 |
+
this_level = forward_fringe
|
| 389 |
+
forward_fringe = []
|
| 390 |
+
for v in this_level:
|
| 391 |
+
for w in Gsucc(v):
|
| 392 |
+
if w in exclude:
|
| 393 |
+
continue
|
| 394 |
+
if w not in pred:
|
| 395 |
+
forward_fringe.append(w)
|
| 396 |
+
pred[w] = v
|
| 397 |
+
if w in succ:
|
| 398 |
+
return pred, succ, w # found path
|
| 399 |
+
else:
|
| 400 |
+
this_level = reverse_fringe
|
| 401 |
+
reverse_fringe = []
|
| 402 |
+
for v in this_level:
|
| 403 |
+
for w in Gpred(v):
|
| 404 |
+
if w in exclude:
|
| 405 |
+
continue
|
| 406 |
+
if w not in succ:
|
| 407 |
+
succ[w] = v
|
| 408 |
+
reverse_fringe.append(w)
|
| 409 |
+
if w in pred:
|
| 410 |
+
return pred, succ, w # found path
|
| 411 |
+
|
| 412 |
+
raise nx.NetworkXNoPath(f"No path between {source} and {target}.")
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/density.py
ADDED
|
@@ -0,0 +1,396 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Fast algorithms for the densest subgraph problem"""
|
| 2 |
+
|
| 3 |
+
import math
|
| 4 |
+
|
| 5 |
+
import networkx as nx
|
| 6 |
+
|
| 7 |
+
__all__ = ["densest_subgraph"]
|
| 8 |
+
|
| 9 |
+
|
| 10 |
+
def _greedy_plus_plus(G, iterations):
|
| 11 |
+
if G.number_of_edges() == 0:
|
| 12 |
+
return 0.0, set()
|
| 13 |
+
if iterations < 1:
|
| 14 |
+
raise ValueError(
|
| 15 |
+
f"The number of iterations must be an integer >= 1. Provided: {iterations}"
|
| 16 |
+
)
|
| 17 |
+
|
| 18 |
+
loads = dict.fromkeys(G.nodes, 0) # Load vector for Greedy++.
|
| 19 |
+
best_density = 0.0 # Highest density encountered.
|
| 20 |
+
best_subgraph = set() # Nodes of the best subgraph found.
|
| 21 |
+
|
| 22 |
+
for _ in range(iterations):
|
| 23 |
+
# Initialize heap for fast access to minimum weighted degree.
|
| 24 |
+
heap = nx.utils.BinaryHeap()
|
| 25 |
+
|
| 26 |
+
# Compute initial weighted degrees and add nodes to the heap.
|
| 27 |
+
for node, degree in G.degree:
|
| 28 |
+
heap.insert(node, loads[node] + degree)
|
| 29 |
+
# Set up tracking for current graph state.
|
| 30 |
+
remaining_nodes = set(G.nodes)
|
| 31 |
+
num_edges = G.number_of_edges()
|
| 32 |
+
current_degrees = dict(G.degree)
|
| 33 |
+
|
| 34 |
+
while remaining_nodes:
|
| 35 |
+
num_nodes = len(remaining_nodes)
|
| 36 |
+
|
| 37 |
+
# Current density of the (implicit) graph
|
| 38 |
+
current_density = num_edges / num_nodes
|
| 39 |
+
|
| 40 |
+
# Update the best density.
|
| 41 |
+
if current_density > best_density:
|
| 42 |
+
best_density = current_density
|
| 43 |
+
best_subgraph = set(remaining_nodes)
|
| 44 |
+
|
| 45 |
+
# Pop the node with the smallest weighted degree.
|
| 46 |
+
node, _ = heap.pop()
|
| 47 |
+
if node not in remaining_nodes:
|
| 48 |
+
continue # Skip nodes already removed.
|
| 49 |
+
|
| 50 |
+
# Update the load of the popped node.
|
| 51 |
+
loads[node] += current_degrees[node]
|
| 52 |
+
|
| 53 |
+
# Update neighbors' degrees and the heap.
|
| 54 |
+
for neighbor in G.neighbors(node):
|
| 55 |
+
if neighbor in remaining_nodes:
|
| 56 |
+
current_degrees[neighbor] -= 1
|
| 57 |
+
num_edges -= 1
|
| 58 |
+
heap.insert(neighbor, loads[neighbor] + current_degrees[neighbor])
|
| 59 |
+
|
| 60 |
+
# Remove the node from the remaining nodes.
|
| 61 |
+
remaining_nodes.remove(node)
|
| 62 |
+
|
| 63 |
+
return best_density, best_subgraph
|
| 64 |
+
|
| 65 |
+
|
| 66 |
+
def _fractional_peeling(G, b, x, node_to_idx, edge_to_idx):
|
| 67 |
+
"""
|
| 68 |
+
Optimized fractional peeling using NumPy arrays.
|
| 69 |
+
|
| 70 |
+
Parameters
|
| 71 |
+
----------
|
| 72 |
+
G : networkx.Graph
|
| 73 |
+
The input graph.
|
| 74 |
+
b : numpy.ndarray
|
| 75 |
+
Induced load vector.
|
| 76 |
+
x : numpy.ndarray
|
| 77 |
+
Fractional edge values.
|
| 78 |
+
node_to_idx : dict
|
| 79 |
+
Mapping from node to index.
|
| 80 |
+
edge_to_idx : dict
|
| 81 |
+
Mapping from edge to index.
|
| 82 |
+
|
| 83 |
+
Returns
|
| 84 |
+
-------
|
| 85 |
+
best_density : float
|
| 86 |
+
The best density found.
|
| 87 |
+
best_subgraph : set
|
| 88 |
+
The subset of nodes defining the densest subgraph.
|
| 89 |
+
"""
|
| 90 |
+
heap = nx.utils.BinaryHeap()
|
| 91 |
+
|
| 92 |
+
remaining_nodes = set(G.nodes)
|
| 93 |
+
|
| 94 |
+
# Initialize heap with b values
|
| 95 |
+
for idx in remaining_nodes:
|
| 96 |
+
heap.insert(idx, b[idx])
|
| 97 |
+
|
| 98 |
+
num_edges = G.number_of_edges()
|
| 99 |
+
|
| 100 |
+
best_density = 0.0
|
| 101 |
+
best_subgraph = set()
|
| 102 |
+
|
| 103 |
+
while remaining_nodes:
|
| 104 |
+
num_nodes = len(remaining_nodes)
|
| 105 |
+
current_density = num_edges / num_nodes
|
| 106 |
+
|
| 107 |
+
if current_density > best_density:
|
| 108 |
+
best_density = current_density
|
| 109 |
+
best_subgraph = set(remaining_nodes)
|
| 110 |
+
|
| 111 |
+
# Pop the node with the smallest b
|
| 112 |
+
node, _ = heap.pop()
|
| 113 |
+
while node not in remaining_nodes:
|
| 114 |
+
node, _ = heap.pop() # Clean the heap from stale values
|
| 115 |
+
|
| 116 |
+
# Update neighbors b values by subtracting fractional x value
|
| 117 |
+
for neighbor in G.neighbors(node):
|
| 118 |
+
if neighbor in remaining_nodes:
|
| 119 |
+
neighbor_idx = node_to_idx[neighbor]
|
| 120 |
+
# Take off fractional value
|
| 121 |
+
b[neighbor_idx] -= x[edge_to_idx[(neighbor, node)]]
|
| 122 |
+
num_edges -= 1
|
| 123 |
+
heap.insert(neighbor, b[neighbor_idx])
|
| 124 |
+
|
| 125 |
+
remaining_nodes.remove(node) # peel off node
|
| 126 |
+
|
| 127 |
+
return best_density, best_subgraph
|
| 128 |
+
|
| 129 |
+
|
| 130 |
+
def _fista(G, iterations):
|
| 131 |
+
if G.number_of_edges() == 0:
|
| 132 |
+
return 0.0, set()
|
| 133 |
+
if iterations < 1:
|
| 134 |
+
raise ValueError(
|
| 135 |
+
f"The number of iterations must be an integer >= 1. Provided: {iterations}"
|
| 136 |
+
)
|
| 137 |
+
import numpy as np
|
| 138 |
+
|
| 139 |
+
# 1. Node Mapping: Assign a unique index to each node and edge
|
| 140 |
+
node_to_idx = {node: idx for idx, node in enumerate(G)}
|
| 141 |
+
num_nodes = G.number_of_nodes()
|
| 142 |
+
num_undirected_edges = G.number_of_edges()
|
| 143 |
+
|
| 144 |
+
# 2. Edge Mapping: Assign a unique index to each bidirectional edge
|
| 145 |
+
bidirectional_edges = [(u, v) for u, v in G.edges] + [(v, u) for u, v in G.edges]
|
| 146 |
+
edge_to_idx = {edge: idx for idx, edge in enumerate(bidirectional_edges)}
|
| 147 |
+
|
| 148 |
+
num_edges = len(bidirectional_edges)
|
| 149 |
+
|
| 150 |
+
# 3. Reverse Edge Mapping: Map each (bidirectional) edge to its reverse edge index
|
| 151 |
+
reverse_edge_idx = np.empty(num_edges, dtype=np.int32)
|
| 152 |
+
for idx in range(num_undirected_edges):
|
| 153 |
+
reverse_edge_idx[idx] = num_undirected_edges + idx
|
| 154 |
+
for idx in range(num_undirected_edges, 2 * num_undirected_edges):
|
| 155 |
+
reverse_edge_idx[idx] = idx - num_undirected_edges
|
| 156 |
+
|
| 157 |
+
# 4. Initialize Variables as NumPy Arrays
|
| 158 |
+
x = np.full(num_edges, 0.5, dtype=np.float32)
|
| 159 |
+
y = x.copy()
|
| 160 |
+
z = np.zeros(num_edges, dtype=np.float32)
|
| 161 |
+
b = np.zeros(num_nodes, dtype=np.float32) # Induced load vector
|
| 162 |
+
tk = 1.0 # Momentum term
|
| 163 |
+
|
| 164 |
+
# 5. Precompute Edge Source Indices
|
| 165 |
+
edge_src_indices = np.array(
|
| 166 |
+
[node_to_idx[u] for u, _ in bidirectional_edges], dtype=np.int32
|
| 167 |
+
)
|
| 168 |
+
|
| 169 |
+
# 6. Compute Learning Rate
|
| 170 |
+
max_degree = max(deg for _, deg in G.degree)
|
| 171 |
+
# 0.9 for floating point errs when max_degree is very large
|
| 172 |
+
learning_rate = 0.9 / max_degree
|
| 173 |
+
|
| 174 |
+
# 7. Iterative Updates
|
| 175 |
+
for _ in range(iterations):
|
| 176 |
+
# 7a. Update b: sum y over outgoing edges for each node
|
| 177 |
+
b[:] = 0.0 # Reset b to zero
|
| 178 |
+
np.add.at(b, edge_src_indices, y) # b_u = \sum_{v : (u,v) \in E(G)} y_{uv}
|
| 179 |
+
|
| 180 |
+
# 7b. Compute z, z_{uv} = y_{uv} - 2 * learning_rate * b_u
|
| 181 |
+
z = y - 2.0 * learning_rate * b[edge_src_indices]
|
| 182 |
+
|
| 183 |
+
# 7c. Update Momentum Term
|
| 184 |
+
tknew = (1.0 + math.sqrt(1 + 4.0 * tk**2)) / 2.0
|
| 185 |
+
|
| 186 |
+
# 7d. Update x in a vectorized manner, x_{uv} = (z_{uv} - z_{vu} + 1.0) / 2.0
|
| 187 |
+
new_xuv = (z - z[reverse_edge_idx] + 1.0) / 2.0
|
| 188 |
+
clamped_x = np.clip(new_xuv, 0.0, 1.0) # Clamp x_{uv} between 0 and 1
|
| 189 |
+
|
| 190 |
+
# Update y using the FISTA update formula (similar to gradient descent)
|
| 191 |
+
y = (
|
| 192 |
+
clamped_x
|
| 193 |
+
+ ((tk - 1.0) / tknew) * (clamped_x - x)
|
| 194 |
+
+ (tk / tknew) * (clamped_x - y)
|
| 195 |
+
)
|
| 196 |
+
|
| 197 |
+
# Update x
|
| 198 |
+
x = clamped_x
|
| 199 |
+
|
| 200 |
+
# Update tk, the momemntum term
|
| 201 |
+
tk = tknew
|
| 202 |
+
|
| 203 |
+
# Rebalance the b values! Otherwise performance is a bit suboptimal.
|
| 204 |
+
b[:] = 0.0
|
| 205 |
+
np.add.at(b, edge_src_indices, x) # b_u = \sum_{v : (u,v) \in E(G)} x_{uv}
|
| 206 |
+
|
| 207 |
+
# Extract the actual (approximate) dense subgraph.
|
| 208 |
+
return _fractional_peeling(G, b, x, node_to_idx, edge_to_idx)
|
| 209 |
+
|
| 210 |
+
|
| 211 |
+
ALGORITHMS = {"greedy++": _greedy_plus_plus, "fista": _fista}
|
| 212 |
+
|
| 213 |
+
|
| 214 |
+
@nx.utils.not_implemented_for("directed")
|
| 215 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 216 |
+
@nx._dispatchable
|
| 217 |
+
def densest_subgraph(G, iterations=1, *, method="fista"):
|
| 218 |
+
r"""Returns an approximate densest subgraph for a graph `G`.
|
| 219 |
+
|
| 220 |
+
This function runs an iterative algorithm to find the densest subgraph,
|
| 221 |
+
and returns both the density and the subgraph. For a discussion on the
|
| 222 |
+
notion of density used and the different algorithms available on
|
| 223 |
+
networkx, please see the Notes section below.
|
| 224 |
+
|
| 225 |
+
Parameters
|
| 226 |
+
----------
|
| 227 |
+
G : NetworkX graph
|
| 228 |
+
Undirected graph.
|
| 229 |
+
|
| 230 |
+
iterations : int, optional (default=1)
|
| 231 |
+
Number of iterations to use for the iterative algorithm. Can be
|
| 232 |
+
specified positionally or as a keyword argument.
|
| 233 |
+
|
| 234 |
+
method : string, optional (default='fista')
|
| 235 |
+
The algorithm to use to approximate the densest subgraph. Supported
|
| 236 |
+
options: 'greedy++' by Boob et al. [2]_ and 'fista' by Harb et al. [3]_.
|
| 237 |
+
Must be specified as a keyword argument. Other inputs produce a
|
| 238 |
+
ValueError.
|
| 239 |
+
|
| 240 |
+
Returns
|
| 241 |
+
-------
|
| 242 |
+
d : float
|
| 243 |
+
The density of the approximate subgraph found.
|
| 244 |
+
|
| 245 |
+
S : set
|
| 246 |
+
The subset of nodes defining the approximate densest subgraph.
|
| 247 |
+
|
| 248 |
+
Examples
|
| 249 |
+
--------
|
| 250 |
+
>>> G = nx.star_graph(4)
|
| 251 |
+
>>> nx.approximation.densest_subgraph(G, iterations=1)
|
| 252 |
+
(0.8, {0, 1, 2, 3, 4})
|
| 253 |
+
|
| 254 |
+
Notes
|
| 255 |
+
-----
|
| 256 |
+
**Problem Definition:**
|
| 257 |
+
The densest subgraph problem (DSG) asks to find the subgraph
|
| 258 |
+
$S \subseteq V(G)$ with maximum density. For a subset of the nodes of
|
| 259 |
+
$G$, $S \subseteq V(G)$, define $E(S) = \{ (u,v) : (u,v)\in E(G),
|
| 260 |
+
u\in S, v\in S \}$ as the set of edges with both endpoints in $S$.
|
| 261 |
+
The density of $S$ is defined as $|E(S)|/|S|$, the ratio between the
|
| 262 |
+
edges in the subgraph $G[S]$ and the number of nodes in that subgraph.
|
| 263 |
+
Note that this is different from the standard graph theoretic definition
|
| 264 |
+
of density, defined as $\frac{2|E(S)|}{|S|(|S|-1)}$, for historical
|
| 265 |
+
reasons.
|
| 266 |
+
|
| 267 |
+
**Exact Algorithms:**
|
| 268 |
+
The densest subgraph problem is polynomial time solvable using maximum
|
| 269 |
+
flow, commonly referred to as Goldberg's algorithm. However, the
|
| 270 |
+
algorithm is quite involved. It first binary searches on the optimal
|
| 271 |
+
density, $d^\ast$. For a guess of the density $d$, it sets up a flow
|
| 272 |
+
network $G'$ with size $O(m)$. The maximum flow solution either
|
| 273 |
+
informs the algorithm that no subgraph with density $d$ exists, or it
|
| 274 |
+
provides a subgraph with density at least $d$. However, this is
|
| 275 |
+
inherently bottlenecked by the maximum flow algorithm. For example, [2]_
|
| 276 |
+
notes that Goldberg’s algorithm was not feasible on many large graphs
|
| 277 |
+
even though they used a highly optimized maximum flow library.
|
| 278 |
+
|
| 279 |
+
**Charikar's Greedy Peeling:**
|
| 280 |
+
While exact solution algorithms are quite involved, there are several
|
| 281 |
+
known approximation algorithms for the densest subgraph problem.
|
| 282 |
+
|
| 283 |
+
Charikar [1]_ described a very simple 1/2-approximation algorithm for DSG
|
| 284 |
+
known as the greedy "peeling" algorithm. The algorithm creates an
|
| 285 |
+
ordering of the nodes as follows. The first node $v_1$ is the one with
|
| 286 |
+
the smallest degree in $G$ (ties broken arbitrarily). It selects
|
| 287 |
+
$v_2$ to be the smallest degree node in $G \setminus v_1$. Letting
|
| 288 |
+
$G_i$ be the graph after removing $v_1, ..., v_i$ (with $G_0=G$),
|
| 289 |
+
the algorithm returns the graph among $G_0, ..., G_n$ with the highest
|
| 290 |
+
density.
|
| 291 |
+
|
| 292 |
+
**Greedy++:**
|
| 293 |
+
Boob et al. [2]_ generalized this algorithm into Greedy++, an iterative
|
| 294 |
+
algorithm that runs several rounds of "peeling". In fact, Greedy++ with 1
|
| 295 |
+
iteration is precisely Charikar's algorithm. The algorithm converges to a
|
| 296 |
+
$(1-\epsilon)$ approximate densest subgraph in $O(\Delta(G)\log
|
| 297 |
+
n/\epsilon^2)$ iterations, where $\Delta(G)$ is the maximum degree,
|
| 298 |
+
and $n$ is the number of nodes in $G$. The algorithm also has other
|
| 299 |
+
desirable properties as shown by [4]_ and [5]_.
|
| 300 |
+
|
| 301 |
+
**FISTA Algorithm:**
|
| 302 |
+
Harb et al. [3]_ gave a faster and more scalable algorithm using ideas
|
| 303 |
+
from quadratic programming for the densest subgraph, which is based on a
|
| 304 |
+
fast iterative shrinkage-thresholding algorithm (FISTA) algorithm. It is
|
| 305 |
+
known that computing the densest subgraph can be formulated as the
|
| 306 |
+
following convex optimization problem:
|
| 307 |
+
|
| 308 |
+
Minimize $\sum_{u \in V(G)} b_u^2$
|
| 309 |
+
|
| 310 |
+
Subject to:
|
| 311 |
+
|
| 312 |
+
$b_u = \sum_{v: \{u,v\} \in E(G)} x_{uv}$ for all $u \in V(G)$
|
| 313 |
+
|
| 314 |
+
$x_{uv} + x_{vu} = 1.0$ for all $\{u,v\} \in E(G)$
|
| 315 |
+
|
| 316 |
+
$x_{uv} \geq 0, x_{vu} \geq 0$ for all $\{u,v\} \in E(G)$
|
| 317 |
+
|
| 318 |
+
Here, $x_{uv}$ represents the fraction of edge $\{u,v\}$ assigned to
|
| 319 |
+
$u$, and $x_{vu}$ to $v$.
|
| 320 |
+
|
| 321 |
+
The FISTA algorithm efficiently solves this convex program using gradient
|
| 322 |
+
descent with projections. For a learning rate $\alpha$, the algorithm
|
| 323 |
+
does:
|
| 324 |
+
|
| 325 |
+
1. **Initialization**: Set $x^{(0)}_{uv} = x^{(0)}_{vu} = 0.5$ for all
|
| 326 |
+
edges as a feasible solution.
|
| 327 |
+
|
| 328 |
+
2. **Gradient Update**: For iteration $k\geq 1$, set
|
| 329 |
+
$x^{(k+1)}_{uv} = x^{(k)}_{uv} - 2 \alpha \sum_{v: \{u,v\} \in E(G)}
|
| 330 |
+
x^{(k)}_{uv}$. However, now $x^{(k+1)}_{uv}$ might be infeasible!
|
| 331 |
+
To ensure feasibility, we project $x^{(k+1)}_{uv}$.
|
| 332 |
+
|
| 333 |
+
3. **Projection to the Feasible Set**: Compute
|
| 334 |
+
$b^{(k+1)}_u = \sum_{v: \{u,v\} \in E(G)} x^{(k)}_{uv}$ for all
|
| 335 |
+
nodes $u$. Define $z^{(k+1)}_{uv} = x^{(k+1)}_{uv} - 2 \alpha
|
| 336 |
+
b^{(k+1)}_u$. Update $x^{(k+1)}_{uv} =
|
| 337 |
+
CLAMP((z^{(k+1)}_{uv} - z^{(k+1)}_{vu} + 1.0) / 2.0)$, where
|
| 338 |
+
$CLAMP(x) = \max(0, \min(1, x))$.
|
| 339 |
+
|
| 340 |
+
With a learning rate of $\alpha=1/\Delta(G)$, where $\Delta(G)$ is
|
| 341 |
+
the maximum degree, the algorithm converges to the optimum solution of
|
| 342 |
+
the convex program.
|
| 343 |
+
|
| 344 |
+
**Fractional Peeling:**
|
| 345 |
+
To obtain a **discrete** subgraph, we use fractional peeling, an
|
| 346 |
+
adaptation of the standard peeling algorithm which peels the minimum
|
| 347 |
+
degree vertex in each iteration, and returns the densest subgraph found
|
| 348 |
+
along the way. Here, we instead peel the vertex with the smallest
|
| 349 |
+
induced load $b_u$:
|
| 350 |
+
|
| 351 |
+
1. Compute $b_u$ and $x_{uv}$.
|
| 352 |
+
|
| 353 |
+
2. Iteratively remove the vertex with the smallest $b_u$, updating its
|
| 354 |
+
neighbors' load by $x_{vu}$.
|
| 355 |
+
|
| 356 |
+
Fractional peeling transforms the approximately optimal fractional
|
| 357 |
+
values $b_u, x_{uv}$ into a discrete subgraph. Unlike traditional
|
| 358 |
+
peeling, which removes the lowest-degree node, this method accounts for
|
| 359 |
+
fractional edge contributions from the convex program.
|
| 360 |
+
|
| 361 |
+
This approach is both scalable and theoretically sound, ensuring a quick
|
| 362 |
+
approximation of the densest subgraph while leveraging fractional load
|
| 363 |
+
balancing.
|
| 364 |
+
|
| 365 |
+
References
|
| 366 |
+
----------
|
| 367 |
+
.. [1] Charikar, Moses. "Greedy approximation algorithms for finding dense
|
| 368 |
+
components in a graph." In International workshop on approximation
|
| 369 |
+
algorithms for combinatorial optimization, pp. 84-95. Berlin, Heidelberg:
|
| 370 |
+
Springer Berlin Heidelberg, 2000.
|
| 371 |
+
|
| 372 |
+
.. [2] Boob, Digvijay, Yu Gao, Richard Peng, Saurabh Sawlani, Charalampos
|
| 373 |
+
Tsourakakis, Di Wang, and Junxing Wang. "Flowless: Extracting densest
|
| 374 |
+
subgraphs without flow computations." In Proceedings of The Web Conference
|
| 375 |
+
2020, pp. 573-583. 2020.
|
| 376 |
+
|
| 377 |
+
.. [3] Harb, Elfarouk, Kent Quanrud, and Chandra Chekuri. "Faster and scalable
|
| 378 |
+
algorithms for densest subgraph and decomposition." Advances in Neural
|
| 379 |
+
Information Processing Systems 35 (2022): 26966-26979.
|
| 380 |
+
|
| 381 |
+
.. [4] Harb, Elfarouk, Kent Quanrud, and Chandra Chekuri. "Convergence to
|
| 382 |
+
lexicographically optimal base in a (contra) polymatroid and applications
|
| 383 |
+
to densest subgraph and tree packing." arXiv preprint arXiv:2305.02987
|
| 384 |
+
(2023).
|
| 385 |
+
|
| 386 |
+
.. [5] Chekuri, Chandra, Kent Quanrud, and Manuel R. Torres. "Densest
|
| 387 |
+
subgraph: Supermodularity, iterative peeling, and flow." In Proceedings of
|
| 388 |
+
the 2022 Annual ACM-SIAM Symposium on Discrete Algorithms (SODA), pp.
|
| 389 |
+
1531-1555. Society for Industrial and Applied Mathematics, 2022.
|
| 390 |
+
"""
|
| 391 |
+
try:
|
| 392 |
+
algo = ALGORITHMS[method]
|
| 393 |
+
except KeyError as e:
|
| 394 |
+
raise ValueError(f"{method} is not a valid choice for an algorithm.") from e
|
| 395 |
+
|
| 396 |
+
return algo(G, iterations)
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/distance_measures.py
ADDED
|
@@ -0,0 +1,150 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Distance measures approximated metrics."""
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
from networkx.utils.decorators import py_random_state
|
| 5 |
+
|
| 6 |
+
__all__ = ["diameter"]
|
| 7 |
+
|
| 8 |
+
|
| 9 |
+
@py_random_state(1)
|
| 10 |
+
@nx._dispatchable(name="approximate_diameter")
|
| 11 |
+
def diameter(G, seed=None):
|
| 12 |
+
"""Returns a lower bound on the diameter of the graph G.
|
| 13 |
+
|
| 14 |
+
The function computes a lower bound on the diameter (i.e., the maximum eccentricity)
|
| 15 |
+
of a directed or undirected graph G. The procedure used varies depending on the graph
|
| 16 |
+
being directed or not.
|
| 17 |
+
|
| 18 |
+
If G is an `undirected` graph, then the function uses the `2-sweep` algorithm [1]_.
|
| 19 |
+
The main idea is to pick the farthest node from a random node and return its eccentricity.
|
| 20 |
+
|
| 21 |
+
Otherwise, if G is a `directed` graph, the function uses the `2-dSweep` algorithm [2]_,
|
| 22 |
+
The procedure starts by selecting a random source node $s$ from which it performs a
|
| 23 |
+
forward and a backward BFS. Let $a_1$ and $a_2$ be the farthest nodes in the forward and
|
| 24 |
+
backward cases, respectively. Then, it computes the backward eccentricity of $a_1$ using
|
| 25 |
+
a backward BFS and the forward eccentricity of $a_2$ using a forward BFS.
|
| 26 |
+
Finally, it returns the best lower bound between the two.
|
| 27 |
+
|
| 28 |
+
In both cases, the time complexity is linear with respect to the size of G.
|
| 29 |
+
|
| 30 |
+
Parameters
|
| 31 |
+
----------
|
| 32 |
+
G : NetworkX graph
|
| 33 |
+
|
| 34 |
+
seed : integer, random_state, or None (default)
|
| 35 |
+
Indicator of random number generation state.
|
| 36 |
+
See :ref:`Randomness<randomness>`.
|
| 37 |
+
|
| 38 |
+
Returns
|
| 39 |
+
-------
|
| 40 |
+
d : integer
|
| 41 |
+
Lower Bound on the Diameter of G
|
| 42 |
+
|
| 43 |
+
Examples
|
| 44 |
+
--------
|
| 45 |
+
>>> G = nx.path_graph(10) # undirected graph
|
| 46 |
+
>>> nx.diameter(G)
|
| 47 |
+
9
|
| 48 |
+
>>> G = nx.cycle_graph(3, create_using=nx.DiGraph) # directed graph
|
| 49 |
+
>>> nx.diameter(G)
|
| 50 |
+
2
|
| 51 |
+
|
| 52 |
+
Raises
|
| 53 |
+
------
|
| 54 |
+
NetworkXError
|
| 55 |
+
If the graph is empty or
|
| 56 |
+
If the graph is undirected and not connected or
|
| 57 |
+
If the graph is directed and not strongly connected.
|
| 58 |
+
|
| 59 |
+
See Also
|
| 60 |
+
--------
|
| 61 |
+
networkx.algorithms.distance_measures.diameter
|
| 62 |
+
|
| 63 |
+
References
|
| 64 |
+
----------
|
| 65 |
+
.. [1] Magnien, Clémence, Matthieu Latapy, and Michel Habib.
|
| 66 |
+
*Fast computation of empirically tight bounds for the diameter of massive graphs.*
|
| 67 |
+
Journal of Experimental Algorithmics (JEA), 2009.
|
| 68 |
+
https://arxiv.org/pdf/0904.2728.pdf
|
| 69 |
+
.. [2] Crescenzi, Pierluigi, Roberto Grossi, Leonardo Lanzi, and Andrea Marino.
|
| 70 |
+
*On computing the diameter of real-world directed (weighted) graphs.*
|
| 71 |
+
International Symposium on Experimental Algorithms. Springer, Berlin, Heidelberg, 2012.
|
| 72 |
+
https://courses.cs.ut.ee/MTAT.03.238/2014_fall/uploads/Main/diameter.pdf
|
| 73 |
+
"""
|
| 74 |
+
# if G is empty
|
| 75 |
+
if not G:
|
| 76 |
+
raise nx.NetworkXError("Expected non-empty NetworkX graph!")
|
| 77 |
+
# if there's only a node
|
| 78 |
+
if G.number_of_nodes() == 1:
|
| 79 |
+
return 0
|
| 80 |
+
# if G is directed
|
| 81 |
+
if G.is_directed():
|
| 82 |
+
return _two_sweep_directed(G, seed)
|
| 83 |
+
# else if G is undirected
|
| 84 |
+
return _two_sweep_undirected(G, seed)
|
| 85 |
+
|
| 86 |
+
|
| 87 |
+
def _two_sweep_undirected(G, seed):
|
| 88 |
+
"""Helper function for finding a lower bound on the diameter
|
| 89 |
+
for undirected Graphs.
|
| 90 |
+
|
| 91 |
+
The idea is to pick the farthest node from a random node
|
| 92 |
+
and return its eccentricity.
|
| 93 |
+
|
| 94 |
+
``G`` is a NetworkX undirected graph.
|
| 95 |
+
|
| 96 |
+
.. note::
|
| 97 |
+
|
| 98 |
+
``seed`` is a random.Random or numpy.random.RandomState instance
|
| 99 |
+
"""
|
| 100 |
+
# select a random source node
|
| 101 |
+
source = seed.choice(list(G))
|
| 102 |
+
# get the distances to the other nodes
|
| 103 |
+
distances = nx.shortest_path_length(G, source)
|
| 104 |
+
# if some nodes have not been visited, then the graph is not connected
|
| 105 |
+
if len(distances) != len(G):
|
| 106 |
+
raise nx.NetworkXError("Graph not connected.")
|
| 107 |
+
# take a node that is (one of) the farthest nodes from the source
|
| 108 |
+
*_, node = distances
|
| 109 |
+
# return the eccentricity of the node
|
| 110 |
+
return nx.eccentricity(G, node)
|
| 111 |
+
|
| 112 |
+
|
| 113 |
+
def _two_sweep_directed(G, seed):
|
| 114 |
+
"""Helper function for finding a lower bound on the diameter
|
| 115 |
+
for directed Graphs.
|
| 116 |
+
|
| 117 |
+
It implements 2-dSweep, the directed version of the 2-sweep algorithm.
|
| 118 |
+
The algorithm follows the following steps.
|
| 119 |
+
1. Select a source node $s$ at random.
|
| 120 |
+
2. Perform a forward BFS from $s$ to select a node $a_1$ at the maximum
|
| 121 |
+
distance from the source, and compute $LB_1$, the backward eccentricity of $a_1$.
|
| 122 |
+
3. Perform a backward BFS from $s$ to select a node $a_2$ at the maximum
|
| 123 |
+
distance from the source, and compute $LB_2$, the forward eccentricity of $a_2$.
|
| 124 |
+
4. Return the maximum between $LB_1$ and $LB_2$.
|
| 125 |
+
|
| 126 |
+
``G`` is a NetworkX directed graph.
|
| 127 |
+
|
| 128 |
+
.. note::
|
| 129 |
+
|
| 130 |
+
``seed`` is a random.Random or numpy.random.RandomState instance
|
| 131 |
+
"""
|
| 132 |
+
# get a new digraph G' with the edges reversed in the opposite direction
|
| 133 |
+
G_reversed = G.reverse()
|
| 134 |
+
# select a random source node
|
| 135 |
+
source = seed.choice(list(G))
|
| 136 |
+
# compute forward distances from source
|
| 137 |
+
forward_distances = nx.shortest_path_length(G, source)
|
| 138 |
+
# compute backward distances from source
|
| 139 |
+
backward_distances = nx.shortest_path_length(G_reversed, source)
|
| 140 |
+
# if either the source can't reach every node or not every node
|
| 141 |
+
# can reach the source, then the graph is not strongly connected
|
| 142 |
+
n = len(G)
|
| 143 |
+
if len(forward_distances) != n or len(backward_distances) != n:
|
| 144 |
+
raise nx.NetworkXError("DiGraph not strongly connected.")
|
| 145 |
+
# take a node a_1 at the maximum distance from the source in G
|
| 146 |
+
*_, a_1 = forward_distances
|
| 147 |
+
# take a node a_2 at the maximum distance from the source in G_reversed
|
| 148 |
+
*_, a_2 = backward_distances
|
| 149 |
+
# return the max between the backward eccentricity of a_1 and the forward eccentricity of a_2
|
| 150 |
+
return max(nx.eccentricity(G_reversed, a_1), nx.eccentricity(G, a_2))
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/dominating_set.py
ADDED
|
@@ -0,0 +1,149 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for finding node and edge dominating sets.
|
| 2 |
+
|
| 3 |
+
A `dominating set`_ for an undirected graph *G* with vertex set *V*
|
| 4 |
+
and edge set *E* is a subset *D* of *V* such that every vertex not in
|
| 5 |
+
*D* is adjacent to at least one member of *D*. An `edge dominating set`_
|
| 6 |
+
is a subset *F* of *E* such that every edge not in *F* is
|
| 7 |
+
incident to an endpoint of at least one edge in *F*.
|
| 8 |
+
|
| 9 |
+
.. _dominating set: https://en.wikipedia.org/wiki/Dominating_set
|
| 10 |
+
.. _edge dominating set: https://en.wikipedia.org/wiki/Edge_dominating_set
|
| 11 |
+
|
| 12 |
+
"""
|
| 13 |
+
|
| 14 |
+
import networkx as nx
|
| 15 |
+
|
| 16 |
+
from ...utils import not_implemented_for
|
| 17 |
+
from ..matching import maximal_matching
|
| 18 |
+
|
| 19 |
+
__all__ = ["min_weighted_dominating_set", "min_edge_dominating_set"]
|
| 20 |
+
|
| 21 |
+
|
| 22 |
+
# TODO Why doesn't this algorithm work for directed graphs?
|
| 23 |
+
@not_implemented_for("directed")
|
| 24 |
+
@nx._dispatchable(node_attrs="weight")
|
| 25 |
+
def min_weighted_dominating_set(G, weight=None):
|
| 26 |
+
r"""Returns a dominating set that approximates the minimum weight node
|
| 27 |
+
dominating set.
|
| 28 |
+
|
| 29 |
+
Parameters
|
| 30 |
+
----------
|
| 31 |
+
G : NetworkX graph
|
| 32 |
+
Undirected graph.
|
| 33 |
+
|
| 34 |
+
weight : string
|
| 35 |
+
The node attribute storing the weight of an node. If provided,
|
| 36 |
+
the node attribute with this key must be a number for each
|
| 37 |
+
node. If not provided, each node is assumed to have weight one.
|
| 38 |
+
|
| 39 |
+
Returns
|
| 40 |
+
-------
|
| 41 |
+
min_weight_dominating_set : set
|
| 42 |
+
A set of nodes, the sum of whose weights is no more than `(\log
|
| 43 |
+
w(V)) w(V^*)`, where `w(V)` denotes the sum of the weights of
|
| 44 |
+
each node in the graph and `w(V^*)` denotes the sum of the
|
| 45 |
+
weights of each node in the minimum weight dominating set.
|
| 46 |
+
|
| 47 |
+
Examples
|
| 48 |
+
--------
|
| 49 |
+
>>> G = nx.Graph([(0, 1), (0, 4), (1, 4), (1, 2), (2, 3), (3, 4), (2, 5)])
|
| 50 |
+
>>> nx.approximation.min_weighted_dominating_set(G)
|
| 51 |
+
{1, 2, 4}
|
| 52 |
+
|
| 53 |
+
Raises
|
| 54 |
+
------
|
| 55 |
+
NetworkXNotImplemented
|
| 56 |
+
If G is directed.
|
| 57 |
+
|
| 58 |
+
Notes
|
| 59 |
+
-----
|
| 60 |
+
This algorithm computes an approximate minimum weighted dominating
|
| 61 |
+
set for the graph `G`. The returned solution has weight `(\log
|
| 62 |
+
w(V)) w(V^*)`, where `w(V)` denotes the sum of the weights of each
|
| 63 |
+
node in the graph and `w(V^*)` denotes the sum of the weights of
|
| 64 |
+
each node in the minimum weight dominating set for the graph.
|
| 65 |
+
|
| 66 |
+
This implementation of the algorithm runs in $O(m)$ time, where $m$
|
| 67 |
+
is the number of edges in the graph.
|
| 68 |
+
|
| 69 |
+
References
|
| 70 |
+
----------
|
| 71 |
+
.. [1] Vazirani, Vijay V.
|
| 72 |
+
*Approximation Algorithms*.
|
| 73 |
+
Springer Science & Business Media, 2001.
|
| 74 |
+
|
| 75 |
+
"""
|
| 76 |
+
# The unique dominating set for the null graph is the empty set.
|
| 77 |
+
if len(G) == 0:
|
| 78 |
+
return set()
|
| 79 |
+
|
| 80 |
+
# This is the dominating set that will eventually be returned.
|
| 81 |
+
dom_set = set()
|
| 82 |
+
|
| 83 |
+
def _cost(node_and_neighborhood):
|
| 84 |
+
"""Returns the cost-effectiveness of greedily choosing the given
|
| 85 |
+
node.
|
| 86 |
+
|
| 87 |
+
`node_and_neighborhood` is a two-tuple comprising a node and its
|
| 88 |
+
closed neighborhood.
|
| 89 |
+
|
| 90 |
+
"""
|
| 91 |
+
v, neighborhood = node_and_neighborhood
|
| 92 |
+
return G.nodes[v].get(weight, 1) / len(neighborhood - dom_set)
|
| 93 |
+
|
| 94 |
+
# This is a set of all vertices not already covered by the
|
| 95 |
+
# dominating set.
|
| 96 |
+
vertices = set(G)
|
| 97 |
+
# This is a dictionary mapping each node to the closed neighborhood
|
| 98 |
+
# of that node.
|
| 99 |
+
neighborhoods = {v: {v} | set(G[v]) for v in G}
|
| 100 |
+
|
| 101 |
+
# Continue until all vertices are adjacent to some node in the
|
| 102 |
+
# dominating set.
|
| 103 |
+
while vertices:
|
| 104 |
+
# Find the most cost-effective node to add, along with its
|
| 105 |
+
# closed neighborhood.
|
| 106 |
+
dom_node, min_set = min(neighborhoods.items(), key=_cost)
|
| 107 |
+
# Add the node to the dominating set and reduce the remaining
|
| 108 |
+
# set of nodes to cover.
|
| 109 |
+
dom_set.add(dom_node)
|
| 110 |
+
del neighborhoods[dom_node]
|
| 111 |
+
vertices -= min_set
|
| 112 |
+
|
| 113 |
+
return dom_set
|
| 114 |
+
|
| 115 |
+
|
| 116 |
+
@nx._dispatchable
|
| 117 |
+
def min_edge_dominating_set(G):
|
| 118 |
+
r"""Returns minimum cardinality edge dominating set.
|
| 119 |
+
|
| 120 |
+
Parameters
|
| 121 |
+
----------
|
| 122 |
+
G : NetworkX graph
|
| 123 |
+
Undirected graph
|
| 124 |
+
|
| 125 |
+
Returns
|
| 126 |
+
-------
|
| 127 |
+
min_edge_dominating_set : set
|
| 128 |
+
Returns a set of dominating edges whose size is no more than 2 * OPT.
|
| 129 |
+
|
| 130 |
+
Examples
|
| 131 |
+
--------
|
| 132 |
+
>>> G = nx.petersen_graph()
|
| 133 |
+
>>> nx.approximation.min_edge_dominating_set(G)
|
| 134 |
+
{(0, 1), (4, 9), (6, 8), (5, 7), (2, 3)}
|
| 135 |
+
|
| 136 |
+
Raises
|
| 137 |
+
------
|
| 138 |
+
ValueError
|
| 139 |
+
If the input graph `G` is empty.
|
| 140 |
+
|
| 141 |
+
Notes
|
| 142 |
+
-----
|
| 143 |
+
The algorithm computes an approximate solution to the edge dominating set
|
| 144 |
+
problem. The result is no more than 2 * OPT in terms of size of the set.
|
| 145 |
+
Runtime of the algorithm is $O(|E|)$.
|
| 146 |
+
"""
|
| 147 |
+
if not G:
|
| 148 |
+
raise ValueError("Expected non-empty NetworkX graph!")
|
| 149 |
+
return maximal_matching(G)
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/kcomponents.py
ADDED
|
@@ -0,0 +1,367 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Fast approximation for k-component structure"""
|
| 2 |
+
|
| 3 |
+
import itertools
|
| 4 |
+
from collections import defaultdict
|
| 5 |
+
from collections.abc import Mapping
|
| 6 |
+
from functools import cached_property
|
| 7 |
+
|
| 8 |
+
import networkx as nx
|
| 9 |
+
from networkx.algorithms.approximation import local_node_connectivity
|
| 10 |
+
from networkx.exception import NetworkXError
|
| 11 |
+
from networkx.utils import not_implemented_for
|
| 12 |
+
|
| 13 |
+
__all__ = ["k_components"]
|
| 14 |
+
|
| 15 |
+
|
| 16 |
+
@not_implemented_for("directed")
|
| 17 |
+
@nx._dispatchable(name="approximate_k_components")
|
| 18 |
+
def k_components(G, min_density=0.95):
|
| 19 |
+
r"""Returns the approximate k-component structure of a graph G.
|
| 20 |
+
|
| 21 |
+
A `k`-component is a maximal subgraph of a graph G that has, at least,
|
| 22 |
+
node connectivity `k`: we need to remove at least `k` nodes to break it
|
| 23 |
+
into more components. `k`-components have an inherent hierarchical
|
| 24 |
+
structure because they are nested in terms of connectivity: a connected
|
| 25 |
+
graph can contain several 2-components, each of which can contain
|
| 26 |
+
one or more 3-components, and so forth.
|
| 27 |
+
|
| 28 |
+
This implementation is based on the fast heuristics to approximate
|
| 29 |
+
the `k`-component structure of a graph [1]_. Which, in turn, it is based on
|
| 30 |
+
a fast approximation algorithm for finding good lower bounds of the number
|
| 31 |
+
of node independent paths between two nodes [2]_.
|
| 32 |
+
|
| 33 |
+
Parameters
|
| 34 |
+
----------
|
| 35 |
+
G : NetworkX graph
|
| 36 |
+
Undirected graph
|
| 37 |
+
|
| 38 |
+
min_density : Float
|
| 39 |
+
Density relaxation threshold. Default value 0.95
|
| 40 |
+
|
| 41 |
+
Returns
|
| 42 |
+
-------
|
| 43 |
+
k_components : dict
|
| 44 |
+
Dictionary with connectivity level `k` as key and a list of
|
| 45 |
+
sets of nodes that form a k-component of level `k` as values.
|
| 46 |
+
|
| 47 |
+
Raises
|
| 48 |
+
------
|
| 49 |
+
NetworkXNotImplemented
|
| 50 |
+
If G is directed.
|
| 51 |
+
|
| 52 |
+
Examples
|
| 53 |
+
--------
|
| 54 |
+
>>> # Petersen graph has 10 nodes and it is triconnected, thus all
|
| 55 |
+
>>> # nodes are in a single component on all three connectivity levels
|
| 56 |
+
>>> from networkx.algorithms import approximation as apxa
|
| 57 |
+
>>> G = nx.petersen_graph()
|
| 58 |
+
>>> k_components = apxa.k_components(G)
|
| 59 |
+
|
| 60 |
+
Notes
|
| 61 |
+
-----
|
| 62 |
+
The logic of the approximation algorithm for computing the `k`-component
|
| 63 |
+
structure [1]_ is based on repeatedly applying simple and fast algorithms
|
| 64 |
+
for `k`-cores and biconnected components in order to narrow down the
|
| 65 |
+
number of pairs of nodes over which we have to compute White and Newman's
|
| 66 |
+
approximation algorithm for finding node independent paths [2]_. More
|
| 67 |
+
formally, this algorithm is based on Whitney's theorem, which states
|
| 68 |
+
an inclusion relation among node connectivity, edge connectivity, and
|
| 69 |
+
minimum degree for any graph G. This theorem implies that every
|
| 70 |
+
`k`-component is nested inside a `k`-edge-component, which in turn,
|
| 71 |
+
is contained in a `k`-core. Thus, this algorithm computes node independent
|
| 72 |
+
paths among pairs of nodes in each biconnected part of each `k`-core,
|
| 73 |
+
and repeats this procedure for each `k` from 3 to the maximal core number
|
| 74 |
+
of a node in the input graph.
|
| 75 |
+
|
| 76 |
+
Because, in practice, many nodes of the core of level `k` inside a
|
| 77 |
+
bicomponent actually are part of a component of level k, the auxiliary
|
| 78 |
+
graph needed for the algorithm is likely to be very dense. Thus, we use
|
| 79 |
+
a complement graph data structure (see `AntiGraph`) to save memory.
|
| 80 |
+
AntiGraph only stores information of the edges that are *not* present
|
| 81 |
+
in the actual auxiliary graph. When applying algorithms to this
|
| 82 |
+
complement graph data structure, it behaves as if it were the dense
|
| 83 |
+
version.
|
| 84 |
+
|
| 85 |
+
See also
|
| 86 |
+
--------
|
| 87 |
+
k_components
|
| 88 |
+
|
| 89 |
+
References
|
| 90 |
+
----------
|
| 91 |
+
.. [1] Torrents, J. and F. Ferraro (2015) Structural Cohesion:
|
| 92 |
+
Visualization and Heuristics for Fast Computation.
|
| 93 |
+
https://arxiv.org/pdf/1503.04476v1
|
| 94 |
+
|
| 95 |
+
.. [2] White, Douglas R., and Mark Newman (2001) A Fast Algorithm for
|
| 96 |
+
Node-Independent Paths. Santa Fe Institute Working Paper #01-07-035
|
| 97 |
+
https://www.santafe.edu/research/results/working-papers/fast-approximation-algorithms-for-finding-node-ind
|
| 98 |
+
|
| 99 |
+
.. [3] Moody, J. and D. White (2003). Social cohesion and embeddedness:
|
| 100 |
+
A hierarchical conception of social groups.
|
| 101 |
+
American Sociological Review 68(1), 103--28.
|
| 102 |
+
https://doi.org/10.2307/3088904
|
| 103 |
+
|
| 104 |
+
"""
|
| 105 |
+
# Dictionary with connectivity level (k) as keys and a list of
|
| 106 |
+
# sets of nodes that form a k-component as values
|
| 107 |
+
k_components = defaultdict(list)
|
| 108 |
+
# make a few functions local for speed
|
| 109 |
+
node_connectivity = local_node_connectivity
|
| 110 |
+
k_core = nx.k_core
|
| 111 |
+
core_number = nx.core_number
|
| 112 |
+
biconnected_components = nx.biconnected_components
|
| 113 |
+
combinations = itertools.combinations
|
| 114 |
+
# Exact solution for k = {1,2}
|
| 115 |
+
# There is a linear time algorithm for triconnectivity, if we had an
|
| 116 |
+
# implementation available we could start from k = 4.
|
| 117 |
+
for component in nx.connected_components(G):
|
| 118 |
+
# isolated nodes have connectivity 0
|
| 119 |
+
comp = set(component)
|
| 120 |
+
if len(comp) > 1:
|
| 121 |
+
k_components[1].append(comp)
|
| 122 |
+
for bicomponent in nx.biconnected_components(G):
|
| 123 |
+
# avoid considering dyads as bicomponents
|
| 124 |
+
bicomp = set(bicomponent)
|
| 125 |
+
if len(bicomp) > 2:
|
| 126 |
+
k_components[2].append(bicomp)
|
| 127 |
+
# There is no k-component of k > maximum core number
|
| 128 |
+
# \kappa(G) <= \lambda(G) <= \delta(G)
|
| 129 |
+
g_cnumber = core_number(G)
|
| 130 |
+
max_core = max(g_cnumber.values())
|
| 131 |
+
for k in range(3, max_core + 1):
|
| 132 |
+
C = k_core(G, k, core_number=g_cnumber)
|
| 133 |
+
for nodes in biconnected_components(C):
|
| 134 |
+
# Build a subgraph SG induced by the nodes that are part of
|
| 135 |
+
# each biconnected component of the k-core subgraph C.
|
| 136 |
+
if len(nodes) < k:
|
| 137 |
+
continue
|
| 138 |
+
SG = G.subgraph(nodes)
|
| 139 |
+
# Build auxiliary graph
|
| 140 |
+
H = _AntiGraph()
|
| 141 |
+
H.add_nodes_from(SG.nodes())
|
| 142 |
+
for u, v in combinations(SG, 2):
|
| 143 |
+
K = node_connectivity(SG, u, v, cutoff=k)
|
| 144 |
+
if k > K:
|
| 145 |
+
H.add_edge(u, v)
|
| 146 |
+
for h_nodes in biconnected_components(H):
|
| 147 |
+
if len(h_nodes) <= k:
|
| 148 |
+
continue
|
| 149 |
+
SH = H.subgraph(h_nodes)
|
| 150 |
+
for Gc in _cliques_heuristic(SG, SH, k, min_density):
|
| 151 |
+
for k_nodes in biconnected_components(Gc):
|
| 152 |
+
Gk = nx.k_core(SG.subgraph(k_nodes), k)
|
| 153 |
+
if len(Gk) <= k:
|
| 154 |
+
continue
|
| 155 |
+
k_components[k].append(set(Gk))
|
| 156 |
+
return k_components
|
| 157 |
+
|
| 158 |
+
|
| 159 |
+
def _cliques_heuristic(G, H, k, min_density):
|
| 160 |
+
h_cnumber = nx.core_number(H)
|
| 161 |
+
for i, c_value in enumerate(sorted(set(h_cnumber.values()), reverse=True)):
|
| 162 |
+
cands = {n for n, c in h_cnumber.items() if c == c_value}
|
| 163 |
+
# Skip checking for overlap for the highest core value
|
| 164 |
+
if i == 0:
|
| 165 |
+
overlap = False
|
| 166 |
+
else:
|
| 167 |
+
overlap = set.intersection(
|
| 168 |
+
*[{x for x in H[n] if x not in cands} for n in cands]
|
| 169 |
+
)
|
| 170 |
+
if overlap and len(overlap) < k:
|
| 171 |
+
SH = H.subgraph(cands | overlap)
|
| 172 |
+
else:
|
| 173 |
+
SH = H.subgraph(cands)
|
| 174 |
+
sh_cnumber = nx.core_number(SH)
|
| 175 |
+
SG = nx.k_core(G.subgraph(SH), k)
|
| 176 |
+
while not (_same(sh_cnumber) and nx.density(SH) >= min_density):
|
| 177 |
+
# This subgraph must be writable => .copy()
|
| 178 |
+
SH = H.subgraph(SG).copy()
|
| 179 |
+
if len(SH) <= k:
|
| 180 |
+
break
|
| 181 |
+
sh_cnumber = nx.core_number(SH)
|
| 182 |
+
sh_deg = dict(SH.degree())
|
| 183 |
+
min_deg = min(sh_deg.values())
|
| 184 |
+
SH.remove_nodes_from(n for n, d in sh_deg.items() if d == min_deg)
|
| 185 |
+
SG = nx.k_core(G.subgraph(SH), k)
|
| 186 |
+
else:
|
| 187 |
+
yield SG
|
| 188 |
+
|
| 189 |
+
|
| 190 |
+
def _same(measure, tol=0):
|
| 191 |
+
vals = set(measure.values())
|
| 192 |
+
if (max(vals) - min(vals)) <= tol:
|
| 193 |
+
return True
|
| 194 |
+
return False
|
| 195 |
+
|
| 196 |
+
|
| 197 |
+
class _AntiGraph(nx.Graph):
|
| 198 |
+
"""
|
| 199 |
+
Class for complement graphs.
|
| 200 |
+
|
| 201 |
+
The main goal is to be able to work with big and dense graphs with
|
| 202 |
+
a low memory footprint.
|
| 203 |
+
|
| 204 |
+
In this class you add the edges that *do not exist* in the dense graph,
|
| 205 |
+
the report methods of the class return the neighbors, the edges and
|
| 206 |
+
the degree as if it was the dense graph. Thus it's possible to use
|
| 207 |
+
an instance of this class with some of NetworkX functions. In this
|
| 208 |
+
case we only use k-core, connected_components, and biconnected_components.
|
| 209 |
+
"""
|
| 210 |
+
|
| 211 |
+
all_edge_dict = {"weight": 1}
|
| 212 |
+
|
| 213 |
+
def single_edge_dict(self):
|
| 214 |
+
return self.all_edge_dict
|
| 215 |
+
|
| 216 |
+
edge_attr_dict_factory = single_edge_dict # type: ignore[assignment]
|
| 217 |
+
|
| 218 |
+
def __getitem__(self, n):
|
| 219 |
+
"""Returns a dict of neighbors of node n in the dense graph.
|
| 220 |
+
|
| 221 |
+
Parameters
|
| 222 |
+
----------
|
| 223 |
+
n : node
|
| 224 |
+
A node in the graph.
|
| 225 |
+
|
| 226 |
+
Returns
|
| 227 |
+
-------
|
| 228 |
+
adj_dict : dictionary
|
| 229 |
+
The adjacency dictionary for nodes connected to n.
|
| 230 |
+
|
| 231 |
+
"""
|
| 232 |
+
all_edge_dict = self.all_edge_dict
|
| 233 |
+
return dict.fromkeys(set(self._adj) - set(self._adj[n]) - {n}, all_edge_dict)
|
| 234 |
+
|
| 235 |
+
def neighbors(self, n):
|
| 236 |
+
"""Returns an iterator over all neighbors of node n in the
|
| 237 |
+
dense graph.
|
| 238 |
+
"""
|
| 239 |
+
try:
|
| 240 |
+
return iter(set(self._adj) - set(self._adj[n]) - {n})
|
| 241 |
+
except KeyError as err:
|
| 242 |
+
raise NetworkXError(f"The node {n} is not in the graph.") from err
|
| 243 |
+
|
| 244 |
+
class AntiAtlasView(Mapping):
|
| 245 |
+
"""An adjacency inner dict for AntiGraph"""
|
| 246 |
+
|
| 247 |
+
def __init__(self, graph, node):
|
| 248 |
+
self._graph = graph
|
| 249 |
+
self._atlas = graph._adj[node]
|
| 250 |
+
self._node = node
|
| 251 |
+
|
| 252 |
+
def __len__(self):
|
| 253 |
+
return len(self._graph) - len(self._atlas) - 1
|
| 254 |
+
|
| 255 |
+
def __iter__(self):
|
| 256 |
+
return (n for n in self._graph if n not in self._atlas and n != self._node)
|
| 257 |
+
|
| 258 |
+
def __getitem__(self, nbr):
|
| 259 |
+
nbrs = set(self._graph._adj) - set(self._atlas) - {self._node}
|
| 260 |
+
if nbr in nbrs:
|
| 261 |
+
return self._graph.all_edge_dict
|
| 262 |
+
raise KeyError(nbr)
|
| 263 |
+
|
| 264 |
+
class AntiAdjacencyView(AntiAtlasView):
|
| 265 |
+
"""An adjacency outer dict for AntiGraph"""
|
| 266 |
+
|
| 267 |
+
def __init__(self, graph):
|
| 268 |
+
self._graph = graph
|
| 269 |
+
self._atlas = graph._adj
|
| 270 |
+
|
| 271 |
+
def __len__(self):
|
| 272 |
+
return len(self._atlas)
|
| 273 |
+
|
| 274 |
+
def __iter__(self):
|
| 275 |
+
return iter(self._graph)
|
| 276 |
+
|
| 277 |
+
def __getitem__(self, node):
|
| 278 |
+
if node not in self._graph:
|
| 279 |
+
raise KeyError(node)
|
| 280 |
+
return self._graph.AntiAtlasView(self._graph, node)
|
| 281 |
+
|
| 282 |
+
@cached_property
|
| 283 |
+
def adj(self):
|
| 284 |
+
return self.AntiAdjacencyView(self)
|
| 285 |
+
|
| 286 |
+
def subgraph(self, nodes):
|
| 287 |
+
"""This subgraph method returns a full AntiGraph. Not a View"""
|
| 288 |
+
nodes = set(nodes)
|
| 289 |
+
G = _AntiGraph()
|
| 290 |
+
G.add_nodes_from(nodes)
|
| 291 |
+
for n in G:
|
| 292 |
+
Gnbrs = G.adjlist_inner_dict_factory()
|
| 293 |
+
G._adj[n] = Gnbrs
|
| 294 |
+
for nbr, d in self._adj[n].items():
|
| 295 |
+
if nbr in G._adj:
|
| 296 |
+
Gnbrs[nbr] = d
|
| 297 |
+
G._adj[nbr][n] = d
|
| 298 |
+
G.graph = self.graph
|
| 299 |
+
return G
|
| 300 |
+
|
| 301 |
+
class AntiDegreeView(nx.reportviews.DegreeView):
|
| 302 |
+
def __iter__(self):
|
| 303 |
+
all_nodes = set(self._succ)
|
| 304 |
+
for n in self._nodes:
|
| 305 |
+
nbrs = all_nodes - set(self._succ[n]) - {n}
|
| 306 |
+
yield (n, len(nbrs))
|
| 307 |
+
|
| 308 |
+
def __getitem__(self, n):
|
| 309 |
+
nbrs = set(self._succ) - set(self._succ[n]) - {n}
|
| 310 |
+
# AntiGraph is a ThinGraph so all edges have weight 1
|
| 311 |
+
return len(nbrs) + (n in nbrs)
|
| 312 |
+
|
| 313 |
+
@cached_property
|
| 314 |
+
def degree(self):
|
| 315 |
+
"""Returns an iterator for (node, degree) and degree for single node.
|
| 316 |
+
|
| 317 |
+
The node degree is the number of edges adjacent to the node.
|
| 318 |
+
|
| 319 |
+
Parameters
|
| 320 |
+
----------
|
| 321 |
+
nbunch : iterable container, optional (default=all nodes)
|
| 322 |
+
A container of nodes. The container will be iterated
|
| 323 |
+
through once.
|
| 324 |
+
|
| 325 |
+
weight : string or None, optional (default=None)
|
| 326 |
+
The edge attribute that holds the numerical value used
|
| 327 |
+
as a weight. If None, then each edge has weight 1.
|
| 328 |
+
The degree is the sum of the edge weights adjacent to the node.
|
| 329 |
+
|
| 330 |
+
Returns
|
| 331 |
+
-------
|
| 332 |
+
deg:
|
| 333 |
+
Degree of the node, if a single node is passed as argument.
|
| 334 |
+
nd_iter : an iterator
|
| 335 |
+
The iterator returns two-tuples of (node, degree).
|
| 336 |
+
|
| 337 |
+
See Also
|
| 338 |
+
--------
|
| 339 |
+
degree
|
| 340 |
+
|
| 341 |
+
Examples
|
| 342 |
+
--------
|
| 343 |
+
>>> G = nx.path_graph(4)
|
| 344 |
+
>>> G.degree(0) # node 0 with degree 1
|
| 345 |
+
1
|
| 346 |
+
>>> list(G.degree([0, 1]))
|
| 347 |
+
[(0, 1), (1, 2)]
|
| 348 |
+
|
| 349 |
+
"""
|
| 350 |
+
return self.AntiDegreeView(self)
|
| 351 |
+
|
| 352 |
+
def adjacency(self):
|
| 353 |
+
"""Returns an iterator of (node, adjacency set) tuples for all nodes
|
| 354 |
+
in the dense graph.
|
| 355 |
+
|
| 356 |
+
This is the fastest way to look at every edge.
|
| 357 |
+
For directed graphs, only outgoing adjacencies are included.
|
| 358 |
+
|
| 359 |
+
Returns
|
| 360 |
+
-------
|
| 361 |
+
adj_iter : iterator
|
| 362 |
+
An iterator of (node, adjacency set) for all nodes in
|
| 363 |
+
the graph.
|
| 364 |
+
|
| 365 |
+
"""
|
| 366 |
+
for n in self._adj:
|
| 367 |
+
yield (n, set(self._adj) - set(self._adj[n]) - {n})
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/matching.py
ADDED
|
@@ -0,0 +1,44 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
**************
|
| 3 |
+
Graph Matching
|
| 4 |
+
**************
|
| 5 |
+
|
| 6 |
+
Given a graph G = (V,E), a matching M in G is a set of pairwise non-adjacent
|
| 7 |
+
edges; that is, no two edges share a common vertex.
|
| 8 |
+
|
| 9 |
+
`Wikipedia: Matching <https://en.wikipedia.org/wiki/Matching_(graph_theory)>`_
|
| 10 |
+
"""
|
| 11 |
+
|
| 12 |
+
import networkx as nx
|
| 13 |
+
|
| 14 |
+
__all__ = ["min_maximal_matching"]
|
| 15 |
+
|
| 16 |
+
|
| 17 |
+
@nx._dispatchable
|
| 18 |
+
def min_maximal_matching(G):
|
| 19 |
+
r"""Returns the minimum maximal matching of G. That is, out of all maximal
|
| 20 |
+
matchings of the graph G, the smallest is returned.
|
| 21 |
+
|
| 22 |
+
Parameters
|
| 23 |
+
----------
|
| 24 |
+
G : NetworkX graph
|
| 25 |
+
Undirected graph
|
| 26 |
+
|
| 27 |
+
Returns
|
| 28 |
+
-------
|
| 29 |
+
min_maximal_matching : set
|
| 30 |
+
Returns a set of edges such that no two edges share a common endpoint
|
| 31 |
+
and every edge not in the set shares some common endpoint in the set.
|
| 32 |
+
Cardinality will be 2*OPT in the worst case.
|
| 33 |
+
|
| 34 |
+
Notes
|
| 35 |
+
-----
|
| 36 |
+
The algorithm computes an approximate solution for the minimum maximal
|
| 37 |
+
cardinality matching problem. The solution is no more than 2 * OPT in size.
|
| 38 |
+
Runtime is $O(|E|)$.
|
| 39 |
+
|
| 40 |
+
References
|
| 41 |
+
----------
|
| 42 |
+
.. [1] Vazirani, Vijay Approximation Algorithms (2001)
|
| 43 |
+
"""
|
| 44 |
+
return nx.maximal_matching(G)
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/maxcut.py
ADDED
|
@@ -0,0 +1,143 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
import networkx as nx
|
| 2 |
+
from networkx.utils.decorators import not_implemented_for, py_random_state
|
| 3 |
+
|
| 4 |
+
__all__ = ["randomized_partitioning", "one_exchange"]
|
| 5 |
+
|
| 6 |
+
|
| 7 |
+
@not_implemented_for("directed")
|
| 8 |
+
@not_implemented_for("multigraph")
|
| 9 |
+
@py_random_state(1)
|
| 10 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 11 |
+
def randomized_partitioning(G, seed=None, p=0.5, weight=None):
|
| 12 |
+
"""Compute a random partitioning of the graph nodes and its cut value.
|
| 13 |
+
|
| 14 |
+
A partitioning is calculated by observing each node
|
| 15 |
+
and deciding to add it to the partition with probability `p`,
|
| 16 |
+
returning a random cut and its corresponding value (the
|
| 17 |
+
sum of weights of edges connecting different partitions).
|
| 18 |
+
|
| 19 |
+
Parameters
|
| 20 |
+
----------
|
| 21 |
+
G : NetworkX graph
|
| 22 |
+
|
| 23 |
+
seed : integer, random_state, or None (default)
|
| 24 |
+
Indicator of random number generation state.
|
| 25 |
+
See :ref:`Randomness<randomness>`.
|
| 26 |
+
|
| 27 |
+
p : scalar
|
| 28 |
+
Probability for each node to be part of the first partition.
|
| 29 |
+
Should be in [0,1]
|
| 30 |
+
|
| 31 |
+
weight : object
|
| 32 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 33 |
+
have weight one.
|
| 34 |
+
|
| 35 |
+
Returns
|
| 36 |
+
-------
|
| 37 |
+
cut_size : scalar
|
| 38 |
+
Value of the minimum cut.
|
| 39 |
+
|
| 40 |
+
partition : pair of node sets
|
| 41 |
+
A partitioning of the nodes that defines a minimum cut.
|
| 42 |
+
|
| 43 |
+
Examples
|
| 44 |
+
--------
|
| 45 |
+
>>> G = nx.complete_graph(5)
|
| 46 |
+
>>> cut_size, partition = nx.approximation.randomized_partitioning(G, seed=1)
|
| 47 |
+
>>> cut_size
|
| 48 |
+
6
|
| 49 |
+
>>> partition
|
| 50 |
+
({0, 3, 4}, {1, 2})
|
| 51 |
+
|
| 52 |
+
Raises
|
| 53 |
+
------
|
| 54 |
+
NetworkXNotImplemented
|
| 55 |
+
If the graph is directed or is a multigraph.
|
| 56 |
+
"""
|
| 57 |
+
cut = {node for node in G.nodes() if seed.random() < p}
|
| 58 |
+
cut_size = nx.algorithms.cut_size(G, cut, weight=weight)
|
| 59 |
+
partition = (cut, G.nodes - cut)
|
| 60 |
+
return cut_size, partition
|
| 61 |
+
|
| 62 |
+
|
| 63 |
+
def _swap_node_partition(cut, node):
|
| 64 |
+
return cut - {node} if node in cut else cut.union({node})
|
| 65 |
+
|
| 66 |
+
|
| 67 |
+
@not_implemented_for("directed")
|
| 68 |
+
@not_implemented_for("multigraph")
|
| 69 |
+
@py_random_state(2)
|
| 70 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 71 |
+
def one_exchange(G, initial_cut=None, seed=None, weight=None):
|
| 72 |
+
"""Compute a partitioning of the graphs nodes and the corresponding cut value.
|
| 73 |
+
|
| 74 |
+
Use a greedy one exchange strategy to find a locally maximal cut
|
| 75 |
+
and its value, it works by finding the best node (one that gives
|
| 76 |
+
the highest gain to the cut value) to add to the current cut
|
| 77 |
+
and repeats this process until no improvement can be made.
|
| 78 |
+
|
| 79 |
+
Parameters
|
| 80 |
+
----------
|
| 81 |
+
G : networkx Graph
|
| 82 |
+
Graph to find a maximum cut for.
|
| 83 |
+
|
| 84 |
+
initial_cut : set
|
| 85 |
+
Cut to use as a starting point. If not supplied the algorithm
|
| 86 |
+
starts with an empty cut.
|
| 87 |
+
|
| 88 |
+
seed : integer, random_state, or None (default)
|
| 89 |
+
Indicator of random number generation state.
|
| 90 |
+
See :ref:`Randomness<randomness>`.
|
| 91 |
+
|
| 92 |
+
weight : object
|
| 93 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 94 |
+
have weight one.
|
| 95 |
+
|
| 96 |
+
Returns
|
| 97 |
+
-------
|
| 98 |
+
cut_value : scalar
|
| 99 |
+
Value of the maximum cut.
|
| 100 |
+
|
| 101 |
+
partition : pair of node sets
|
| 102 |
+
A partitioning of the nodes that defines a maximum cut.
|
| 103 |
+
|
| 104 |
+
Examples
|
| 105 |
+
--------
|
| 106 |
+
>>> G = nx.complete_graph(5)
|
| 107 |
+
>>> curr_cut_size, partition = nx.approximation.one_exchange(G, seed=1)
|
| 108 |
+
>>> curr_cut_size
|
| 109 |
+
6
|
| 110 |
+
>>> partition
|
| 111 |
+
({0, 2}, {1, 3, 4})
|
| 112 |
+
|
| 113 |
+
Raises
|
| 114 |
+
------
|
| 115 |
+
NetworkXNotImplemented
|
| 116 |
+
If the graph is directed or is a multigraph.
|
| 117 |
+
"""
|
| 118 |
+
if initial_cut is None:
|
| 119 |
+
initial_cut = set()
|
| 120 |
+
cut = set(initial_cut)
|
| 121 |
+
current_cut_size = nx.algorithms.cut_size(G, cut, weight=weight)
|
| 122 |
+
while True:
|
| 123 |
+
nodes = list(G.nodes())
|
| 124 |
+
# Shuffling the nodes ensures random tie-breaks in the following call to max
|
| 125 |
+
seed.shuffle(nodes)
|
| 126 |
+
best_node_to_swap = max(
|
| 127 |
+
nodes,
|
| 128 |
+
key=lambda v: nx.algorithms.cut_size(
|
| 129 |
+
G, _swap_node_partition(cut, v), weight=weight
|
| 130 |
+
),
|
| 131 |
+
default=None,
|
| 132 |
+
)
|
| 133 |
+
potential_cut = _swap_node_partition(cut, best_node_to_swap)
|
| 134 |
+
potential_cut_size = nx.algorithms.cut_size(G, potential_cut, weight=weight)
|
| 135 |
+
|
| 136 |
+
if potential_cut_size > current_cut_size:
|
| 137 |
+
cut = potential_cut
|
| 138 |
+
current_cut_size = potential_cut_size
|
| 139 |
+
else:
|
| 140 |
+
break
|
| 141 |
+
|
| 142 |
+
partition = (cut, G.nodes - cut)
|
| 143 |
+
return current_cut_size, partition
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/ramsey.py
ADDED
|
@@ -0,0 +1,53 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
Ramsey numbers.
|
| 3 |
+
"""
|
| 4 |
+
|
| 5 |
+
import networkx as nx
|
| 6 |
+
from networkx.utils import not_implemented_for
|
| 7 |
+
|
| 8 |
+
from ...utils import arbitrary_element
|
| 9 |
+
|
| 10 |
+
__all__ = ["ramsey_R2"]
|
| 11 |
+
|
| 12 |
+
|
| 13 |
+
@not_implemented_for("directed")
|
| 14 |
+
@not_implemented_for("multigraph")
|
| 15 |
+
@nx._dispatchable
|
| 16 |
+
def ramsey_R2(G):
|
| 17 |
+
r"""Compute the largest clique and largest independent set in `G`.
|
| 18 |
+
|
| 19 |
+
This can be used to estimate bounds for the 2-color
|
| 20 |
+
Ramsey number `R(2;s,t)` for `G`.
|
| 21 |
+
|
| 22 |
+
This is a recursive implementation which could run into trouble
|
| 23 |
+
for large recursions. Note that self-loop edges are ignored.
|
| 24 |
+
|
| 25 |
+
Parameters
|
| 26 |
+
----------
|
| 27 |
+
G : NetworkX graph
|
| 28 |
+
Undirected graph
|
| 29 |
+
|
| 30 |
+
Returns
|
| 31 |
+
-------
|
| 32 |
+
max_pair : (set, set) tuple
|
| 33 |
+
Maximum clique, Maximum independent set.
|
| 34 |
+
|
| 35 |
+
Raises
|
| 36 |
+
------
|
| 37 |
+
NetworkXNotImplemented
|
| 38 |
+
If the graph is directed or is a multigraph.
|
| 39 |
+
"""
|
| 40 |
+
if not G:
|
| 41 |
+
return set(), set()
|
| 42 |
+
|
| 43 |
+
node = arbitrary_element(G)
|
| 44 |
+
nbrs = (nbr for nbr in nx.all_neighbors(G, node) if nbr != node)
|
| 45 |
+
nnbrs = nx.non_neighbors(G, node)
|
| 46 |
+
c_1, i_1 = ramsey_R2(G.subgraph(nbrs).copy())
|
| 47 |
+
c_2, i_2 = ramsey_R2(G.subgraph(nnbrs).copy())
|
| 48 |
+
|
| 49 |
+
c_1.add(node)
|
| 50 |
+
i_2.add(node)
|
| 51 |
+
# Choose the larger of the two cliques and the larger of the two
|
| 52 |
+
# independent sets, according to cardinality.
|
| 53 |
+
return max(c_1, c_2, key=len), max(i_1, i_2, key=len)
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/steinertree.py
ADDED
|
@@ -0,0 +1,248 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
from itertools import chain
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
from networkx.utils import not_implemented_for, pairwise
|
| 5 |
+
|
| 6 |
+
__all__ = ["metric_closure", "steiner_tree"]
|
| 7 |
+
|
| 8 |
+
|
| 9 |
+
@not_implemented_for("directed")
|
| 10 |
+
@nx._dispatchable(edge_attrs="weight", returns_graph=True)
|
| 11 |
+
def metric_closure(G, weight="weight"):
|
| 12 |
+
"""Return the metric closure of a graph.
|
| 13 |
+
|
| 14 |
+
The metric closure of a graph *G* is the complete graph in which each edge
|
| 15 |
+
is weighted by the shortest path distance between the nodes in *G* .
|
| 16 |
+
|
| 17 |
+
Parameters
|
| 18 |
+
----------
|
| 19 |
+
G : NetworkX graph
|
| 20 |
+
|
| 21 |
+
Returns
|
| 22 |
+
-------
|
| 23 |
+
NetworkX graph
|
| 24 |
+
Metric closure of the graph `G`.
|
| 25 |
+
|
| 26 |
+
"""
|
| 27 |
+
M = nx.Graph()
|
| 28 |
+
|
| 29 |
+
Gnodes = set(G)
|
| 30 |
+
|
| 31 |
+
# check for connected graph while processing first node
|
| 32 |
+
all_paths_iter = nx.all_pairs_dijkstra(G, weight=weight)
|
| 33 |
+
u, (distance, path) = next(all_paths_iter)
|
| 34 |
+
if len(G) != len(distance):
|
| 35 |
+
msg = "G is not a connected graph. metric_closure is not defined."
|
| 36 |
+
raise nx.NetworkXError(msg)
|
| 37 |
+
Gnodes.remove(u)
|
| 38 |
+
for v in Gnodes:
|
| 39 |
+
M.add_edge(u, v, distance=distance[v], path=path[v])
|
| 40 |
+
|
| 41 |
+
# first node done -- now process the rest
|
| 42 |
+
for u, (distance, path) in all_paths_iter:
|
| 43 |
+
Gnodes.remove(u)
|
| 44 |
+
for v in Gnodes:
|
| 45 |
+
M.add_edge(u, v, distance=distance[v], path=path[v])
|
| 46 |
+
|
| 47 |
+
return M
|
| 48 |
+
|
| 49 |
+
|
| 50 |
+
def _mehlhorn_steiner_tree(G, terminal_nodes, weight):
|
| 51 |
+
paths = nx.multi_source_dijkstra_path(G, terminal_nodes)
|
| 52 |
+
|
| 53 |
+
d_1 = {}
|
| 54 |
+
s = {}
|
| 55 |
+
for v in G.nodes():
|
| 56 |
+
s[v] = paths[v][0]
|
| 57 |
+
d_1[(v, s[v])] = len(paths[v]) - 1
|
| 58 |
+
|
| 59 |
+
# G1-G4 names match those from the Mehlhorn 1988 paper.
|
| 60 |
+
G_1_prime = nx.Graph()
|
| 61 |
+
for u, v, data in G.edges(data=True):
|
| 62 |
+
su, sv = s[u], s[v]
|
| 63 |
+
weight_here = d_1[(u, su)] + data.get(weight, 1) + d_1[(v, sv)]
|
| 64 |
+
if not G_1_prime.has_edge(su, sv):
|
| 65 |
+
G_1_prime.add_edge(su, sv, weight=weight_here)
|
| 66 |
+
else:
|
| 67 |
+
new_weight = min(weight_here, G_1_prime[su][sv]["weight"])
|
| 68 |
+
G_1_prime.add_edge(su, sv, weight=new_weight)
|
| 69 |
+
|
| 70 |
+
G_2 = nx.minimum_spanning_edges(G_1_prime, data=True)
|
| 71 |
+
|
| 72 |
+
G_3 = nx.Graph()
|
| 73 |
+
for u, v, d in G_2:
|
| 74 |
+
path = nx.shortest_path(G, u, v, weight)
|
| 75 |
+
for n1, n2 in pairwise(path):
|
| 76 |
+
G_3.add_edge(n1, n2)
|
| 77 |
+
|
| 78 |
+
G_3_mst = list(nx.minimum_spanning_edges(G_3, data=False))
|
| 79 |
+
if G.is_multigraph():
|
| 80 |
+
G_3_mst = (
|
| 81 |
+
(u, v, min(G[u][v], key=lambda k: G[u][v][k][weight])) for u, v in G_3_mst
|
| 82 |
+
)
|
| 83 |
+
G_4 = G.edge_subgraph(G_3_mst).copy()
|
| 84 |
+
_remove_nonterminal_leaves(G_4, terminal_nodes)
|
| 85 |
+
return G_4.edges()
|
| 86 |
+
|
| 87 |
+
|
| 88 |
+
def _kou_steiner_tree(G, terminal_nodes, weight):
|
| 89 |
+
# Compute the metric closure only for terminal nodes
|
| 90 |
+
# Create a complete graph H from the metric edges
|
| 91 |
+
H = nx.Graph()
|
| 92 |
+
unvisited_terminals = set(terminal_nodes)
|
| 93 |
+
|
| 94 |
+
# check for connected graph while processing first node
|
| 95 |
+
u = unvisited_terminals.pop()
|
| 96 |
+
distances, paths = nx.single_source_dijkstra(G, source=u, weight=weight)
|
| 97 |
+
if len(G) != len(distances):
|
| 98 |
+
msg = "G is not a connected graph."
|
| 99 |
+
raise nx.NetworkXError(msg)
|
| 100 |
+
for v in unvisited_terminals:
|
| 101 |
+
H.add_edge(u, v, distance=distances[v], path=paths[v])
|
| 102 |
+
|
| 103 |
+
# first node done -- now process the rest
|
| 104 |
+
for u in unvisited_terminals.copy():
|
| 105 |
+
distances, paths = nx.single_source_dijkstra(G, source=u, weight=weight)
|
| 106 |
+
unvisited_terminals.remove(u)
|
| 107 |
+
for v in unvisited_terminals:
|
| 108 |
+
H.add_edge(u, v, distance=distances[v], path=paths[v])
|
| 109 |
+
|
| 110 |
+
# Use the 'distance' attribute of each edge provided by H.
|
| 111 |
+
mst_edges = nx.minimum_spanning_edges(H, weight="distance", data=True)
|
| 112 |
+
|
| 113 |
+
# Create an iterator over each edge in each shortest path; repeats are okay
|
| 114 |
+
mst_all_edges = chain.from_iterable(pairwise(d["path"]) for u, v, d in mst_edges)
|
| 115 |
+
if G.is_multigraph():
|
| 116 |
+
mst_all_edges = (
|
| 117 |
+
(u, v, min(G[u][v], key=lambda k: G[u][v][k][weight]))
|
| 118 |
+
for u, v in mst_all_edges
|
| 119 |
+
)
|
| 120 |
+
|
| 121 |
+
# Find the MST again, over this new set of edges
|
| 122 |
+
G_S = G.edge_subgraph(mst_all_edges)
|
| 123 |
+
T_S = nx.minimum_spanning_edges(G_S, weight="weight", data=False)
|
| 124 |
+
|
| 125 |
+
# Leaf nodes that are not terminal might still remain; remove them here
|
| 126 |
+
T_H = G.edge_subgraph(T_S).copy()
|
| 127 |
+
_remove_nonterminal_leaves(T_H, terminal_nodes)
|
| 128 |
+
|
| 129 |
+
return T_H.edges()
|
| 130 |
+
|
| 131 |
+
|
| 132 |
+
def _remove_nonterminal_leaves(G, terminals):
|
| 133 |
+
terminal_set = set(terminals)
|
| 134 |
+
leaves = {n for n in G if len(set(G[n]) - {n}) == 1}
|
| 135 |
+
nonterminal_leaves = leaves - terminal_set
|
| 136 |
+
|
| 137 |
+
while nonterminal_leaves:
|
| 138 |
+
# Removing a node may create new non-terminal leaves, so we limit
|
| 139 |
+
# search for candidate non-terminal nodes to neighbors of current
|
| 140 |
+
# non-terminal nodes
|
| 141 |
+
candidate_leaves = set.union(*(set(G[n]) for n in nonterminal_leaves))
|
| 142 |
+
candidate_leaves -= nonterminal_leaves | terminal_set
|
| 143 |
+
# Remove current set of non-terminal nodes
|
| 144 |
+
G.remove_nodes_from(nonterminal_leaves)
|
| 145 |
+
# Find any new non-terminal nodes from the set of candidates
|
| 146 |
+
leaves = {n for n in candidate_leaves if len(set(G[n]) - {n}) == 1}
|
| 147 |
+
nonterminal_leaves = leaves - terminal_set
|
| 148 |
+
|
| 149 |
+
|
| 150 |
+
ALGORITHMS = {
|
| 151 |
+
"kou": _kou_steiner_tree,
|
| 152 |
+
"mehlhorn": _mehlhorn_steiner_tree,
|
| 153 |
+
}
|
| 154 |
+
|
| 155 |
+
|
| 156 |
+
@not_implemented_for("directed")
|
| 157 |
+
@nx._dispatchable(preserve_all_attrs=True, returns_graph=True)
|
| 158 |
+
def steiner_tree(G, terminal_nodes, weight="weight", method=None):
|
| 159 |
+
r"""Return an approximation to the minimum Steiner tree of a graph.
|
| 160 |
+
|
| 161 |
+
The minimum Steiner tree of `G` w.r.t a set of `terminal_nodes` (also *S*)
|
| 162 |
+
is a tree within `G` that spans those nodes and has minimum size (sum of
|
| 163 |
+
edge weights) among all such trees.
|
| 164 |
+
|
| 165 |
+
The approximation algorithm is specified with the `method` keyword
|
| 166 |
+
argument. All three available algorithms produce a tree whose weight is
|
| 167 |
+
within a ``(2 - (2 / l))`` factor of the weight of the optimal Steiner tree,
|
| 168 |
+
where ``l`` is the minimum number of leaf nodes across all possible Steiner
|
| 169 |
+
trees.
|
| 170 |
+
|
| 171 |
+
* ``"kou"`` [2]_ (runtime $O(|S| |V|^2)$) computes the minimum spanning tree of
|
| 172 |
+
the subgraph of the metric closure of *G* induced by the terminal nodes,
|
| 173 |
+
where the metric closure of *G* is the complete graph in which each edge is
|
| 174 |
+
weighted by the shortest path distance between the nodes in *G*.
|
| 175 |
+
|
| 176 |
+
* ``"mehlhorn"`` [3]_ (runtime $O(|E|+|V|\log|V|)$) modifies Kou et al.'s
|
| 177 |
+
algorithm, beginning by finding the closest terminal node for each
|
| 178 |
+
non-terminal. This data is used to create a complete graph containing only
|
| 179 |
+
the terminal nodes, in which edge is weighted with the shortest path
|
| 180 |
+
distance between them. The algorithm then proceeds in the same way as Kou
|
| 181 |
+
et al..
|
| 182 |
+
|
| 183 |
+
Parameters
|
| 184 |
+
----------
|
| 185 |
+
G : NetworkX graph
|
| 186 |
+
|
| 187 |
+
terminal_nodes : list
|
| 188 |
+
A list of terminal nodes for which minimum steiner tree is
|
| 189 |
+
to be found.
|
| 190 |
+
|
| 191 |
+
weight : string (default = 'weight')
|
| 192 |
+
Use the edge attribute specified by this string as the edge weight.
|
| 193 |
+
Any edge attribute not present defaults to 1.
|
| 194 |
+
|
| 195 |
+
method : string, optional (default = 'mehlhorn')
|
| 196 |
+
The algorithm to use to approximate the Steiner tree.
|
| 197 |
+
Supported options: 'kou', 'mehlhorn'.
|
| 198 |
+
Other inputs produce a ValueError.
|
| 199 |
+
|
| 200 |
+
Returns
|
| 201 |
+
-------
|
| 202 |
+
NetworkX graph
|
| 203 |
+
Approximation to the minimum steiner tree of `G` induced by
|
| 204 |
+
`terminal_nodes` .
|
| 205 |
+
|
| 206 |
+
Raises
|
| 207 |
+
------
|
| 208 |
+
NetworkXNotImplemented
|
| 209 |
+
If `G` is directed.
|
| 210 |
+
|
| 211 |
+
ValueError
|
| 212 |
+
If the specified `method` is not supported.
|
| 213 |
+
|
| 214 |
+
Notes
|
| 215 |
+
-----
|
| 216 |
+
For multigraphs, the edge between two nodes with minimum weight is the
|
| 217 |
+
edge put into the Steiner tree.
|
| 218 |
+
|
| 219 |
+
|
| 220 |
+
References
|
| 221 |
+
----------
|
| 222 |
+
.. [1] Steiner_tree_problem on Wikipedia.
|
| 223 |
+
https://en.wikipedia.org/wiki/Steiner_tree_problem
|
| 224 |
+
.. [2] Kou, L., G. Markowsky, and L. Berman. 1981.
|
| 225 |
+
‘A Fast Algorithm for Steiner Trees’.
|
| 226 |
+
Acta Informatica 15 (2): 141–45.
|
| 227 |
+
https://doi.org/10.1007/BF00288961.
|
| 228 |
+
.. [3] Mehlhorn, Kurt. 1988.
|
| 229 |
+
‘A Faster Approximation Algorithm for the Steiner Problem in Graphs’.
|
| 230 |
+
Information Processing Letters 27 (3): 125–28.
|
| 231 |
+
https://doi.org/10.1016/0020-0190(88)90066-X.
|
| 232 |
+
"""
|
| 233 |
+
if method is None:
|
| 234 |
+
method = "mehlhorn"
|
| 235 |
+
|
| 236 |
+
try:
|
| 237 |
+
algo = ALGORITHMS[method]
|
| 238 |
+
except KeyError as e:
|
| 239 |
+
raise ValueError(f"{method} is not a valid choice for an algorithm.") from e
|
| 240 |
+
|
| 241 |
+
edges = algo(G, terminal_nodes, weight)
|
| 242 |
+
# For multigraph we should add the minimal weight edge keys
|
| 243 |
+
if G.is_multigraph():
|
| 244 |
+
edges = (
|
| 245 |
+
(u, v, min(G[u][v], key=lambda k: G[u][v][k][weight])) for u, v in edges
|
| 246 |
+
)
|
| 247 |
+
T = G.edge_subgraph(edges)
|
| 248 |
+
return T
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/traveling_salesman.py
ADDED
|
@@ -0,0 +1,1508 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
=================================
|
| 3 |
+
Travelling Salesman Problem (TSP)
|
| 4 |
+
=================================
|
| 5 |
+
|
| 6 |
+
Implementation of approximate algorithms
|
| 7 |
+
for solving and approximating the TSP problem.
|
| 8 |
+
|
| 9 |
+
Categories of algorithms which are implemented:
|
| 10 |
+
|
| 11 |
+
- Christofides (provides a 3/2-approximation of TSP)
|
| 12 |
+
- Greedy
|
| 13 |
+
- Simulated Annealing (SA)
|
| 14 |
+
- Threshold Accepting (TA)
|
| 15 |
+
- Asadpour Asymmetric Traveling Salesman Algorithm
|
| 16 |
+
|
| 17 |
+
The Travelling Salesman Problem tries to find, given the weight
|
| 18 |
+
(distance) between all points where a salesman has to visit, the
|
| 19 |
+
route so that:
|
| 20 |
+
|
| 21 |
+
- The total distance (cost) which the salesman travels is minimized.
|
| 22 |
+
- The salesman returns to the starting point.
|
| 23 |
+
- Note that for a complete graph, the salesman visits each point once.
|
| 24 |
+
|
| 25 |
+
The function `travelling_salesman_problem` allows for incomplete
|
| 26 |
+
graphs by finding all-pairs shortest paths, effectively converting
|
| 27 |
+
the problem to a complete graph problem. It calls one of the
|
| 28 |
+
approximate methods on that problem and then converts the result
|
| 29 |
+
back to the original graph using the previously found shortest paths.
|
| 30 |
+
|
| 31 |
+
TSP is an NP-hard problem in combinatorial optimization,
|
| 32 |
+
important in operations research and theoretical computer science.
|
| 33 |
+
|
| 34 |
+
http://en.wikipedia.org/wiki/Travelling_salesman_problem
|
| 35 |
+
"""
|
| 36 |
+
|
| 37 |
+
import math
|
| 38 |
+
|
| 39 |
+
import networkx as nx
|
| 40 |
+
from networkx.algorithms.tree.mst import random_spanning_tree
|
| 41 |
+
from networkx.utils import not_implemented_for, pairwise, py_random_state
|
| 42 |
+
|
| 43 |
+
__all__ = [
|
| 44 |
+
"traveling_salesman_problem",
|
| 45 |
+
"christofides",
|
| 46 |
+
"asadpour_atsp",
|
| 47 |
+
"greedy_tsp",
|
| 48 |
+
"simulated_annealing_tsp",
|
| 49 |
+
"threshold_accepting_tsp",
|
| 50 |
+
]
|
| 51 |
+
|
| 52 |
+
|
| 53 |
+
def swap_two_nodes(soln, seed):
|
| 54 |
+
"""Swap two nodes in `soln` to give a neighbor solution.
|
| 55 |
+
|
| 56 |
+
Parameters
|
| 57 |
+
----------
|
| 58 |
+
soln : list of nodes
|
| 59 |
+
Current cycle of nodes
|
| 60 |
+
|
| 61 |
+
seed : integer, random_state, or None (default)
|
| 62 |
+
Indicator of random number generation state.
|
| 63 |
+
See :ref:`Randomness<randomness>`.
|
| 64 |
+
|
| 65 |
+
Returns
|
| 66 |
+
-------
|
| 67 |
+
list
|
| 68 |
+
The solution after move is applied. (A neighbor solution.)
|
| 69 |
+
|
| 70 |
+
Notes
|
| 71 |
+
-----
|
| 72 |
+
This function assumes that the incoming list `soln` is a cycle
|
| 73 |
+
(that the first and last element are the same) and also that
|
| 74 |
+
we don't want any move to change the first node in the list
|
| 75 |
+
(and thus not the last node either).
|
| 76 |
+
|
| 77 |
+
The input list is changed as well as returned. Make a copy if needed.
|
| 78 |
+
|
| 79 |
+
See Also
|
| 80 |
+
--------
|
| 81 |
+
move_one_node
|
| 82 |
+
"""
|
| 83 |
+
a, b = seed.sample(range(1, len(soln) - 1), k=2)
|
| 84 |
+
soln[a], soln[b] = soln[b], soln[a]
|
| 85 |
+
return soln
|
| 86 |
+
|
| 87 |
+
|
| 88 |
+
def move_one_node(soln, seed):
|
| 89 |
+
"""Move one node to another position to give a neighbor solution.
|
| 90 |
+
|
| 91 |
+
The node to move and the position to move to are chosen randomly.
|
| 92 |
+
The first and last nodes are left untouched as soln must be a cycle
|
| 93 |
+
starting at that node.
|
| 94 |
+
|
| 95 |
+
Parameters
|
| 96 |
+
----------
|
| 97 |
+
soln : list of nodes
|
| 98 |
+
Current cycle of nodes
|
| 99 |
+
|
| 100 |
+
seed : integer, random_state, or None (default)
|
| 101 |
+
Indicator of random number generation state.
|
| 102 |
+
See :ref:`Randomness<randomness>`.
|
| 103 |
+
|
| 104 |
+
Returns
|
| 105 |
+
-------
|
| 106 |
+
list
|
| 107 |
+
The solution after move is applied. (A neighbor solution.)
|
| 108 |
+
|
| 109 |
+
Notes
|
| 110 |
+
-----
|
| 111 |
+
This function assumes that the incoming list `soln` is a cycle
|
| 112 |
+
(that the first and last element are the same) and also that
|
| 113 |
+
we don't want any move to change the first node in the list
|
| 114 |
+
(and thus not the last node either).
|
| 115 |
+
|
| 116 |
+
The input list is changed as well as returned. Make a copy if needed.
|
| 117 |
+
|
| 118 |
+
See Also
|
| 119 |
+
--------
|
| 120 |
+
swap_two_nodes
|
| 121 |
+
"""
|
| 122 |
+
a, b = seed.sample(range(1, len(soln) - 1), k=2)
|
| 123 |
+
soln.insert(b, soln.pop(a))
|
| 124 |
+
return soln
|
| 125 |
+
|
| 126 |
+
|
| 127 |
+
@not_implemented_for("directed")
|
| 128 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 129 |
+
def christofides(G, weight="weight", tree=None):
|
| 130 |
+
"""Approximate a solution of the traveling salesman problem
|
| 131 |
+
|
| 132 |
+
Compute a 3/2-approximation of the traveling salesman problem
|
| 133 |
+
in a complete undirected graph using Christofides [1]_ algorithm.
|
| 134 |
+
|
| 135 |
+
Parameters
|
| 136 |
+
----------
|
| 137 |
+
G : Graph
|
| 138 |
+
`G` should be a complete weighted undirected graph.
|
| 139 |
+
The distance between all pairs of nodes should be included.
|
| 140 |
+
|
| 141 |
+
weight : string, optional (default="weight")
|
| 142 |
+
Edge data key corresponding to the edge weight.
|
| 143 |
+
If any edge does not have this attribute the weight is set to 1.
|
| 144 |
+
|
| 145 |
+
tree : NetworkX graph or None (default: None)
|
| 146 |
+
A minimum spanning tree of G. Or, if None, the minimum spanning
|
| 147 |
+
tree is computed using :func:`networkx.minimum_spanning_tree`
|
| 148 |
+
|
| 149 |
+
Returns
|
| 150 |
+
-------
|
| 151 |
+
list
|
| 152 |
+
List of nodes in `G` along a cycle with a 3/2-approximation of
|
| 153 |
+
the minimal Hamiltonian cycle.
|
| 154 |
+
|
| 155 |
+
References
|
| 156 |
+
----------
|
| 157 |
+
.. [1] Christofides, Nicos. "Worst-case analysis of a new heuristic for
|
| 158 |
+
the travelling salesman problem." No. RR-388. Carnegie-Mellon Univ
|
| 159 |
+
Pittsburgh Pa Management Sciences Research Group, 1976.
|
| 160 |
+
"""
|
| 161 |
+
# Remove selfloops if necessary
|
| 162 |
+
loop_nodes = nx.nodes_with_selfloops(G)
|
| 163 |
+
try:
|
| 164 |
+
node = next(loop_nodes)
|
| 165 |
+
except StopIteration:
|
| 166 |
+
pass
|
| 167 |
+
else:
|
| 168 |
+
G = G.copy()
|
| 169 |
+
G.remove_edge(node, node)
|
| 170 |
+
G.remove_edges_from((n, n) for n in loop_nodes)
|
| 171 |
+
# Check that G is a complete graph
|
| 172 |
+
N = len(G) - 1
|
| 173 |
+
# This check ignores selfloops which is what we want here.
|
| 174 |
+
if any(len(nbrdict) != N for n, nbrdict in G.adj.items()):
|
| 175 |
+
raise nx.NetworkXError("G must be a complete graph.")
|
| 176 |
+
|
| 177 |
+
if tree is None:
|
| 178 |
+
tree = nx.minimum_spanning_tree(G, weight=weight)
|
| 179 |
+
L = G.copy()
|
| 180 |
+
L.remove_nodes_from([v for v, degree in tree.degree if not (degree % 2)])
|
| 181 |
+
MG = nx.MultiGraph()
|
| 182 |
+
MG.add_edges_from(tree.edges)
|
| 183 |
+
edges = nx.min_weight_matching(L, weight=weight)
|
| 184 |
+
MG.add_edges_from(edges)
|
| 185 |
+
return _shortcutting(nx.eulerian_circuit(MG))
|
| 186 |
+
|
| 187 |
+
|
| 188 |
+
def _shortcutting(circuit):
|
| 189 |
+
"""Remove duplicate nodes in the path"""
|
| 190 |
+
nodes = []
|
| 191 |
+
for u, v in circuit:
|
| 192 |
+
if v in nodes:
|
| 193 |
+
continue
|
| 194 |
+
if not nodes:
|
| 195 |
+
nodes.append(u)
|
| 196 |
+
nodes.append(v)
|
| 197 |
+
nodes.append(nodes[0])
|
| 198 |
+
return nodes
|
| 199 |
+
|
| 200 |
+
|
| 201 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 202 |
+
def traveling_salesman_problem(
|
| 203 |
+
G, weight="weight", nodes=None, cycle=True, method=None, **kwargs
|
| 204 |
+
):
|
| 205 |
+
"""Find the shortest path in `G` connecting specified nodes
|
| 206 |
+
|
| 207 |
+
This function allows approximate solution to the traveling salesman
|
| 208 |
+
problem on networks that are not complete graphs and/or where the
|
| 209 |
+
salesman does not need to visit all nodes.
|
| 210 |
+
|
| 211 |
+
This function proceeds in two steps. First, it creates a complete
|
| 212 |
+
graph using the all-pairs shortest_paths between nodes in `nodes`.
|
| 213 |
+
Edge weights in the new graph are the lengths of the paths
|
| 214 |
+
between each pair of nodes in the original graph.
|
| 215 |
+
Second, an algorithm (default: `christofides` for undirected and
|
| 216 |
+
`asadpour_atsp` for directed) is used to approximate the minimal Hamiltonian
|
| 217 |
+
cycle on this new graph. The available algorithms are:
|
| 218 |
+
|
| 219 |
+
- christofides
|
| 220 |
+
- greedy_tsp
|
| 221 |
+
- simulated_annealing_tsp
|
| 222 |
+
- threshold_accepting_tsp
|
| 223 |
+
- asadpour_atsp
|
| 224 |
+
|
| 225 |
+
Once the Hamiltonian Cycle is found, this function post-processes to
|
| 226 |
+
accommodate the structure of the original graph. If `cycle` is ``False``,
|
| 227 |
+
the biggest weight edge is removed to make a Hamiltonian path.
|
| 228 |
+
Then each edge on the new complete graph used for that analysis is
|
| 229 |
+
replaced by the shortest_path between those nodes on the original graph.
|
| 230 |
+
If the input graph `G` includes edges with weights that do not adhere to
|
| 231 |
+
the triangle inequality, such as when `G` is not a complete graph (i.e
|
| 232 |
+
length of non-existent edges is infinity), then the returned path may
|
| 233 |
+
contain some repeating nodes (other than the starting node).
|
| 234 |
+
|
| 235 |
+
Parameters
|
| 236 |
+
----------
|
| 237 |
+
G : NetworkX graph
|
| 238 |
+
A possibly weighted graph
|
| 239 |
+
|
| 240 |
+
nodes : collection of nodes (default=G.nodes)
|
| 241 |
+
collection (list, set, etc.) of nodes to visit
|
| 242 |
+
|
| 243 |
+
weight : string, optional (default="weight")
|
| 244 |
+
Edge data key corresponding to the edge weight.
|
| 245 |
+
If any edge does not have this attribute the weight is set to 1.
|
| 246 |
+
|
| 247 |
+
cycle : bool (default: True)
|
| 248 |
+
Indicates whether a cycle should be returned, or a path.
|
| 249 |
+
Note: the cycle is the approximate minimal cycle.
|
| 250 |
+
The path simply removes the biggest edge in that cycle.
|
| 251 |
+
|
| 252 |
+
method : function (default: None)
|
| 253 |
+
A function that returns a cycle on all nodes and approximates
|
| 254 |
+
the solution to the traveling salesman problem on a complete
|
| 255 |
+
graph. The returned cycle is then used to find a corresponding
|
| 256 |
+
solution on `G`. `method` should be callable; take inputs
|
| 257 |
+
`G`, and `weight`; and return a list of nodes along the cycle.
|
| 258 |
+
|
| 259 |
+
Provided options include :func:`christofides`, :func:`greedy_tsp`,
|
| 260 |
+
:func:`simulated_annealing_tsp` and :func:`threshold_accepting_tsp`.
|
| 261 |
+
|
| 262 |
+
If `method is None`: use :func:`christofides` for undirected `G` and
|
| 263 |
+
:func:`asadpour_atsp` for directed `G`.
|
| 264 |
+
|
| 265 |
+
**kwargs : dict
|
| 266 |
+
Other keyword arguments to be passed to the `method` function passed in.
|
| 267 |
+
|
| 268 |
+
Returns
|
| 269 |
+
-------
|
| 270 |
+
list
|
| 271 |
+
List of nodes in `G` along a path with an approximation of the minimal
|
| 272 |
+
path through `nodes`.
|
| 273 |
+
|
| 274 |
+
Raises
|
| 275 |
+
------
|
| 276 |
+
NetworkXError
|
| 277 |
+
If `G` is a directed graph it has to be strongly connected or the
|
| 278 |
+
complete version cannot be generated.
|
| 279 |
+
|
| 280 |
+
Examples
|
| 281 |
+
--------
|
| 282 |
+
>>> tsp = nx.approximation.traveling_salesman_problem
|
| 283 |
+
>>> G = nx.cycle_graph(9)
|
| 284 |
+
>>> G[4][5]["weight"] = 5 # all other weights are 1
|
| 285 |
+
>>> tsp(G, nodes=[3, 6])
|
| 286 |
+
[3, 2, 1, 0, 8, 7, 6, 7, 8, 0, 1, 2, 3]
|
| 287 |
+
>>> path = tsp(G, cycle=False)
|
| 288 |
+
>>> path in ([4, 3, 2, 1, 0, 8, 7, 6, 5], [5, 6, 7, 8, 0, 1, 2, 3, 4])
|
| 289 |
+
True
|
| 290 |
+
|
| 291 |
+
While no longer required, you can still build (curry) your own function
|
| 292 |
+
to provide parameter values to the methods.
|
| 293 |
+
|
| 294 |
+
>>> SA_tsp = nx.approximation.simulated_annealing_tsp
|
| 295 |
+
>>> method = lambda G, weight: SA_tsp(G, "greedy", weight=weight, temp=500)
|
| 296 |
+
>>> path = tsp(G, cycle=False, method=method)
|
| 297 |
+
>>> path in ([4, 3, 2, 1, 0, 8, 7, 6, 5], [5, 6, 7, 8, 0, 1, 2, 3, 4])
|
| 298 |
+
True
|
| 299 |
+
|
| 300 |
+
Otherwise, pass other keyword arguments directly into the tsp function.
|
| 301 |
+
|
| 302 |
+
>>> path = tsp(
|
| 303 |
+
... G,
|
| 304 |
+
... cycle=False,
|
| 305 |
+
... method=nx.approximation.simulated_annealing_tsp,
|
| 306 |
+
... init_cycle="greedy",
|
| 307 |
+
... temp=500,
|
| 308 |
+
... )
|
| 309 |
+
>>> path in ([4, 3, 2, 1, 0, 8, 7, 6, 5], [5, 6, 7, 8, 0, 1, 2, 3, 4])
|
| 310 |
+
True
|
| 311 |
+
"""
|
| 312 |
+
if method is None:
|
| 313 |
+
if G.is_directed():
|
| 314 |
+
method = asadpour_atsp
|
| 315 |
+
else:
|
| 316 |
+
method = christofides
|
| 317 |
+
if nodes is None:
|
| 318 |
+
nodes = list(G.nodes)
|
| 319 |
+
|
| 320 |
+
dist = {}
|
| 321 |
+
path = {}
|
| 322 |
+
for n, (d, p) in nx.all_pairs_dijkstra(G, weight=weight):
|
| 323 |
+
dist[n] = d
|
| 324 |
+
path[n] = p
|
| 325 |
+
|
| 326 |
+
if G.is_directed():
|
| 327 |
+
# If the graph is not strongly connected, raise an exception
|
| 328 |
+
if not nx.is_strongly_connected(G):
|
| 329 |
+
raise nx.NetworkXError("G is not strongly connected")
|
| 330 |
+
GG = nx.DiGraph()
|
| 331 |
+
else:
|
| 332 |
+
GG = nx.Graph()
|
| 333 |
+
for u in nodes:
|
| 334 |
+
for v in nodes:
|
| 335 |
+
if u == v:
|
| 336 |
+
continue
|
| 337 |
+
# Ensure that the weight attribute on GG has the
|
| 338 |
+
# same name as the input graph
|
| 339 |
+
GG.add_edge(u, v, **{weight: dist[u][v]})
|
| 340 |
+
|
| 341 |
+
best_GG = method(GG, weight=weight, **kwargs)
|
| 342 |
+
|
| 343 |
+
if not cycle:
|
| 344 |
+
# find and remove the biggest edge
|
| 345 |
+
(u, v) = max(pairwise(best_GG), key=lambda x: dist[x[0]][x[1]])
|
| 346 |
+
pos = best_GG.index(u) + 1
|
| 347 |
+
while best_GG[pos] != v:
|
| 348 |
+
pos = best_GG[pos:].index(u) + 1
|
| 349 |
+
best_GG = best_GG[pos:-1] + best_GG[:pos]
|
| 350 |
+
|
| 351 |
+
best_path = []
|
| 352 |
+
for u, v in pairwise(best_GG):
|
| 353 |
+
best_path.extend(path[u][v][:-1])
|
| 354 |
+
best_path.append(v)
|
| 355 |
+
return best_path
|
| 356 |
+
|
| 357 |
+
|
| 358 |
+
@not_implemented_for("undirected")
|
| 359 |
+
@py_random_state(2)
|
| 360 |
+
@nx._dispatchable(edge_attrs="weight", mutates_input=True)
|
| 361 |
+
def asadpour_atsp(G, weight="weight", seed=None, source=None):
|
| 362 |
+
"""
|
| 363 |
+
Returns an approximate solution to the traveling salesman problem.
|
| 364 |
+
|
| 365 |
+
This approximate solution is one of the best known approximations for the
|
| 366 |
+
asymmetric traveling salesman problem developed by Asadpour et al,
|
| 367 |
+
[1]_. The algorithm first solves the Held-Karp relaxation to find a lower
|
| 368 |
+
bound for the weight of the cycle. Next, it constructs an exponential
|
| 369 |
+
distribution of undirected spanning trees where the probability of an
|
| 370 |
+
edge being in the tree corresponds to the weight of that edge using a
|
| 371 |
+
maximum entropy rounding scheme. Next we sample that distribution
|
| 372 |
+
$2 \\lceil \\ln n \\rceil$ times and save the minimum sampled tree once the
|
| 373 |
+
direction of the arcs is added back to the edges. Finally, we augment
|
| 374 |
+
then short circuit that graph to find the approximate tour for the
|
| 375 |
+
salesman.
|
| 376 |
+
|
| 377 |
+
Parameters
|
| 378 |
+
----------
|
| 379 |
+
G : nx.DiGraph
|
| 380 |
+
The graph should be a complete weighted directed graph. The
|
| 381 |
+
distance between all paris of nodes should be included and the triangle
|
| 382 |
+
inequality should hold. That is, the direct edge between any two nodes
|
| 383 |
+
should be the path of least cost.
|
| 384 |
+
|
| 385 |
+
weight : string, optional (default="weight")
|
| 386 |
+
Edge data key corresponding to the edge weight.
|
| 387 |
+
If any edge does not have this attribute the weight is set to 1.
|
| 388 |
+
|
| 389 |
+
seed : integer, random_state, or None (default)
|
| 390 |
+
Indicator of random number generation state.
|
| 391 |
+
See :ref:`Randomness<randomness>`.
|
| 392 |
+
|
| 393 |
+
source : node label (default=`None`)
|
| 394 |
+
If given, return the cycle starting and ending at the given node.
|
| 395 |
+
|
| 396 |
+
Returns
|
| 397 |
+
-------
|
| 398 |
+
cycle : list of nodes
|
| 399 |
+
Returns the cycle (list of nodes) that a salesman can follow to minimize
|
| 400 |
+
the total weight of the trip.
|
| 401 |
+
|
| 402 |
+
Raises
|
| 403 |
+
------
|
| 404 |
+
NetworkXError
|
| 405 |
+
If `G` is not complete or has less than two nodes, the algorithm raises
|
| 406 |
+
an exception.
|
| 407 |
+
|
| 408 |
+
NetworkXError
|
| 409 |
+
If `source` is not `None` and is not a node in `G`, the algorithm raises
|
| 410 |
+
an exception.
|
| 411 |
+
|
| 412 |
+
NetworkXNotImplemented
|
| 413 |
+
If `G` is an undirected graph.
|
| 414 |
+
|
| 415 |
+
References
|
| 416 |
+
----------
|
| 417 |
+
.. [1] A. Asadpour, M. X. Goemans, A. Madry, S. O. Gharan, and A. Saberi,
|
| 418 |
+
An o(log n/log log n)-approximation algorithm for the asymmetric
|
| 419 |
+
traveling salesman problem, Operations research, 65 (2017),
|
| 420 |
+
pp. 1043–1061
|
| 421 |
+
|
| 422 |
+
Examples
|
| 423 |
+
--------
|
| 424 |
+
>>> import networkx as nx
|
| 425 |
+
>>> import networkx.algorithms.approximation as approx
|
| 426 |
+
>>> G = nx.complete_graph(3, create_using=nx.DiGraph)
|
| 427 |
+
>>> nx.set_edge_attributes(
|
| 428 |
+
... G,
|
| 429 |
+
... {(0, 1): 2, (1, 2): 2, (2, 0): 2, (0, 2): 1, (2, 1): 1, (1, 0): 1},
|
| 430 |
+
... "weight",
|
| 431 |
+
... )
|
| 432 |
+
>>> tour = approx.asadpour_atsp(G, source=0)
|
| 433 |
+
>>> tour
|
| 434 |
+
[0, 2, 1, 0]
|
| 435 |
+
"""
|
| 436 |
+
from math import ceil, exp
|
| 437 |
+
from math import log as ln
|
| 438 |
+
|
| 439 |
+
# Check that G is a complete graph
|
| 440 |
+
N = len(G) - 1
|
| 441 |
+
if N < 1:
|
| 442 |
+
raise nx.NetworkXError("G must have at least two nodes")
|
| 443 |
+
# This check ignores selfloops which is what we want here.
|
| 444 |
+
if any(len(nbrdict) - (n in nbrdict) != N for n, nbrdict in G.adj.items()):
|
| 445 |
+
raise nx.NetworkXError("G is not a complete DiGraph")
|
| 446 |
+
# Check that the source vertex, if given, is in the graph
|
| 447 |
+
if source is not None and source not in G.nodes:
|
| 448 |
+
raise nx.NetworkXError("Given source node not in G.")
|
| 449 |
+
# handle 2 node case
|
| 450 |
+
if N == 1:
|
| 451 |
+
if source is None:
|
| 452 |
+
return list(G)
|
| 453 |
+
return [source, next(n for n in G if n != source)]
|
| 454 |
+
|
| 455 |
+
opt_hk, z_star = held_karp_ascent(G, weight)
|
| 456 |
+
|
| 457 |
+
# Test to see if the ascent method found an integer solution or a fractional
|
| 458 |
+
# solution. If it is integral then z_star is a nx.Graph, otherwise it is
|
| 459 |
+
# a dict
|
| 460 |
+
if not isinstance(z_star, dict):
|
| 461 |
+
# Here we are using the shortcutting method to go from the list of edges
|
| 462 |
+
# returned from eulerian_circuit to a list of nodes
|
| 463 |
+
return _shortcutting(nx.eulerian_circuit(z_star, source=source))
|
| 464 |
+
|
| 465 |
+
# Create the undirected support of z_star
|
| 466 |
+
z_support = nx.MultiGraph()
|
| 467 |
+
for u, v in z_star:
|
| 468 |
+
if (u, v) not in z_support.edges:
|
| 469 |
+
edge_weight = min(G[u][v][weight], G[v][u][weight])
|
| 470 |
+
z_support.add_edge(u, v, **{weight: edge_weight})
|
| 471 |
+
|
| 472 |
+
# Create the exponential distribution of spanning trees
|
| 473 |
+
gamma = spanning_tree_distribution(z_support, z_star)
|
| 474 |
+
|
| 475 |
+
# Write the lambda values to the edges of z_support
|
| 476 |
+
z_support = nx.Graph(z_support)
|
| 477 |
+
lambda_dict = {(u, v): exp(gamma[(u, v)]) for u, v in z_support.edges()}
|
| 478 |
+
nx.set_edge_attributes(z_support, lambda_dict, "weight")
|
| 479 |
+
del gamma, lambda_dict
|
| 480 |
+
|
| 481 |
+
# Sample 2 * ceil( ln(n) ) spanning trees and record the minimum one
|
| 482 |
+
minimum_sampled_tree = None
|
| 483 |
+
minimum_sampled_tree_weight = math.inf
|
| 484 |
+
for _ in range(2 * ceil(ln(G.number_of_nodes()))):
|
| 485 |
+
sampled_tree = random_spanning_tree(z_support, "weight", seed=seed)
|
| 486 |
+
sampled_tree_weight = sampled_tree.size(weight)
|
| 487 |
+
if sampled_tree_weight < minimum_sampled_tree_weight:
|
| 488 |
+
minimum_sampled_tree = sampled_tree.copy()
|
| 489 |
+
minimum_sampled_tree_weight = sampled_tree_weight
|
| 490 |
+
|
| 491 |
+
# Orient the edges in that tree to keep the cost of the tree the same.
|
| 492 |
+
t_star = nx.MultiDiGraph()
|
| 493 |
+
for u, v, d in minimum_sampled_tree.edges(data=weight):
|
| 494 |
+
if d == G[u][v][weight]:
|
| 495 |
+
t_star.add_edge(u, v, **{weight: d})
|
| 496 |
+
else:
|
| 497 |
+
t_star.add_edge(v, u, **{weight: d})
|
| 498 |
+
|
| 499 |
+
# Find the node demands needed to neutralize the flow of t_star in G
|
| 500 |
+
node_demands = {n: t_star.out_degree(n) - t_star.in_degree(n) for n in t_star}
|
| 501 |
+
nx.set_node_attributes(G, node_demands, "demand")
|
| 502 |
+
|
| 503 |
+
# Find the min_cost_flow
|
| 504 |
+
flow_dict = nx.min_cost_flow(G, "demand")
|
| 505 |
+
|
| 506 |
+
# Build the flow into t_star
|
| 507 |
+
for source, values in flow_dict.items():
|
| 508 |
+
for target in values:
|
| 509 |
+
if (source, target) not in t_star.edges and values[target] > 0:
|
| 510 |
+
# IF values[target] > 0 we have to add that many edges
|
| 511 |
+
for _ in range(values[target]):
|
| 512 |
+
t_star.add_edge(source, target)
|
| 513 |
+
|
| 514 |
+
# Return the shortcut eulerian circuit
|
| 515 |
+
circuit = nx.eulerian_circuit(t_star, source=source)
|
| 516 |
+
return _shortcutting(circuit)
|
| 517 |
+
|
| 518 |
+
|
| 519 |
+
@nx._dispatchable(edge_attrs="weight", mutates_input=True, returns_graph=True)
|
| 520 |
+
def held_karp_ascent(G, weight="weight"):
|
| 521 |
+
"""
|
| 522 |
+
Minimizes the Held-Karp relaxation of the TSP for `G`
|
| 523 |
+
|
| 524 |
+
Solves the Held-Karp relaxation of the input complete digraph and scales
|
| 525 |
+
the output solution for use in the Asadpour [1]_ ASTP algorithm.
|
| 526 |
+
|
| 527 |
+
The Held-Karp relaxation defines the lower bound for solutions to the
|
| 528 |
+
ATSP, although it does return a fractional solution. This is used in the
|
| 529 |
+
Asadpour algorithm as an initial solution which is later rounded to a
|
| 530 |
+
integral tree within the spanning tree polytopes. This function solves
|
| 531 |
+
the relaxation with the branch and bound method in [2]_.
|
| 532 |
+
|
| 533 |
+
Parameters
|
| 534 |
+
----------
|
| 535 |
+
G : nx.DiGraph
|
| 536 |
+
The graph should be a complete weighted directed graph.
|
| 537 |
+
The distance between all paris of nodes should be included.
|
| 538 |
+
|
| 539 |
+
weight : string, optional (default="weight")
|
| 540 |
+
Edge data key corresponding to the edge weight.
|
| 541 |
+
If any edge does not have this attribute the weight is set to 1.
|
| 542 |
+
|
| 543 |
+
Returns
|
| 544 |
+
-------
|
| 545 |
+
OPT : float
|
| 546 |
+
The cost for the optimal solution to the Held-Karp relaxation
|
| 547 |
+
z : dict or nx.Graph
|
| 548 |
+
A symmetrized and scaled version of the optimal solution to the
|
| 549 |
+
Held-Karp relaxation for use in the Asadpour algorithm.
|
| 550 |
+
|
| 551 |
+
If an integral solution is found, then that is an optimal solution for
|
| 552 |
+
the ATSP problem and that is returned instead.
|
| 553 |
+
|
| 554 |
+
References
|
| 555 |
+
----------
|
| 556 |
+
.. [1] A. Asadpour, M. X. Goemans, A. Madry, S. O. Gharan, and A. Saberi,
|
| 557 |
+
An o(log n/log log n)-approximation algorithm for the asymmetric
|
| 558 |
+
traveling salesman problem, Operations research, 65 (2017),
|
| 559 |
+
pp. 1043–1061
|
| 560 |
+
|
| 561 |
+
.. [2] M. Held, R. M. Karp, The traveling-salesman problem and minimum
|
| 562 |
+
spanning trees, Operations Research, 1970-11-01, Vol. 18 (6),
|
| 563 |
+
pp.1138-1162
|
| 564 |
+
"""
|
| 565 |
+
import numpy as np
|
| 566 |
+
import scipy as sp
|
| 567 |
+
|
| 568 |
+
def k_pi():
|
| 569 |
+
"""
|
| 570 |
+
Find the set of minimum 1-Arborescences for G at point pi.
|
| 571 |
+
|
| 572 |
+
Returns
|
| 573 |
+
-------
|
| 574 |
+
Set
|
| 575 |
+
The set of minimum 1-Arborescences
|
| 576 |
+
"""
|
| 577 |
+
# Create a copy of G without vertex 1.
|
| 578 |
+
G_1 = G.copy()
|
| 579 |
+
minimum_1_arborescences = set()
|
| 580 |
+
minimum_1_arborescence_weight = math.inf
|
| 581 |
+
|
| 582 |
+
# node is node '1' in the Held and Karp paper
|
| 583 |
+
n = next(G.__iter__())
|
| 584 |
+
G_1.remove_node(n)
|
| 585 |
+
|
| 586 |
+
# Iterate over the spanning arborescences of the graph until we know
|
| 587 |
+
# that we have found the minimum 1-arborescences. My proposed strategy
|
| 588 |
+
# is to find the most extensive root to connect to from 'node 1' and
|
| 589 |
+
# the least expensive one. We then iterate over arborescences until
|
| 590 |
+
# the cost of the basic arborescence is the cost of the minimum one
|
| 591 |
+
# plus the difference between the most and least expensive roots,
|
| 592 |
+
# that way the cost of connecting 'node 1' will by definition not by
|
| 593 |
+
# minimum
|
| 594 |
+
min_root = {"node": None, weight: math.inf}
|
| 595 |
+
max_root = {"node": None, weight: -math.inf}
|
| 596 |
+
for u, v, d in G.edges(n, data=True):
|
| 597 |
+
if d[weight] < min_root[weight]:
|
| 598 |
+
min_root = {"node": v, weight: d[weight]}
|
| 599 |
+
if d[weight] > max_root[weight]:
|
| 600 |
+
max_root = {"node": v, weight: d[weight]}
|
| 601 |
+
|
| 602 |
+
min_in_edge = min(G.in_edges(n, data=True), key=lambda x: x[2][weight])
|
| 603 |
+
min_root[weight] = min_root[weight] + min_in_edge[2][weight]
|
| 604 |
+
max_root[weight] = max_root[weight] + min_in_edge[2][weight]
|
| 605 |
+
|
| 606 |
+
min_arb_weight = math.inf
|
| 607 |
+
for arb in nx.ArborescenceIterator(G_1):
|
| 608 |
+
arb_weight = arb.size(weight)
|
| 609 |
+
if min_arb_weight == math.inf:
|
| 610 |
+
min_arb_weight = arb_weight
|
| 611 |
+
elif arb_weight > min_arb_weight + max_root[weight] - min_root[weight]:
|
| 612 |
+
break
|
| 613 |
+
# We have to pick the root node of the arborescence for the out
|
| 614 |
+
# edge of the first vertex as that is the only node without an
|
| 615 |
+
# edge directed into it.
|
| 616 |
+
for N, deg in arb.in_degree:
|
| 617 |
+
if deg == 0:
|
| 618 |
+
# root found
|
| 619 |
+
arb.add_edge(n, N, **{weight: G[n][N][weight]})
|
| 620 |
+
arb_weight += G[n][N][weight]
|
| 621 |
+
break
|
| 622 |
+
|
| 623 |
+
# We can pick the minimum weight in-edge for the vertex with
|
| 624 |
+
# a cycle. If there are multiple edges with the same, minimum
|
| 625 |
+
# weight, We need to add all of them.
|
| 626 |
+
#
|
| 627 |
+
# Delete the edge (N, v) so that we cannot pick it.
|
| 628 |
+
edge_data = G[N][n]
|
| 629 |
+
G.remove_edge(N, n)
|
| 630 |
+
min_weight = min(G.in_edges(n, data=weight), key=lambda x: x[2])[2]
|
| 631 |
+
min_edges = [
|
| 632 |
+
(u, v, d) for u, v, d in G.in_edges(n, data=weight) if d == min_weight
|
| 633 |
+
]
|
| 634 |
+
for u, v, d in min_edges:
|
| 635 |
+
new_arb = arb.copy()
|
| 636 |
+
new_arb.add_edge(u, v, **{weight: d})
|
| 637 |
+
new_arb_weight = arb_weight + d
|
| 638 |
+
# Check to see the weight of the arborescence, if it is a
|
| 639 |
+
# new minimum, clear all of the old potential minimum
|
| 640 |
+
# 1-arborescences and add this is the only one. If its
|
| 641 |
+
# weight is above the known minimum, do not add it.
|
| 642 |
+
if new_arb_weight < minimum_1_arborescence_weight:
|
| 643 |
+
minimum_1_arborescences.clear()
|
| 644 |
+
minimum_1_arborescence_weight = new_arb_weight
|
| 645 |
+
# We have a 1-arborescence, add it to the set
|
| 646 |
+
if new_arb_weight == minimum_1_arborescence_weight:
|
| 647 |
+
minimum_1_arborescences.add(new_arb)
|
| 648 |
+
G.add_edge(N, n, **edge_data)
|
| 649 |
+
|
| 650 |
+
return minimum_1_arborescences
|
| 651 |
+
|
| 652 |
+
def direction_of_ascent():
|
| 653 |
+
"""
|
| 654 |
+
Find the direction of ascent at point pi.
|
| 655 |
+
|
| 656 |
+
See [1]_ for more information.
|
| 657 |
+
|
| 658 |
+
Returns
|
| 659 |
+
-------
|
| 660 |
+
dict
|
| 661 |
+
A mapping from the nodes of the graph which represents the direction
|
| 662 |
+
of ascent.
|
| 663 |
+
|
| 664 |
+
References
|
| 665 |
+
----------
|
| 666 |
+
.. [1] M. Held, R. M. Karp, The traveling-salesman problem and minimum
|
| 667 |
+
spanning trees, Operations Research, 1970-11-01, Vol. 18 (6),
|
| 668 |
+
pp.1138-1162
|
| 669 |
+
"""
|
| 670 |
+
# 1. Set d equal to the zero n-vector.
|
| 671 |
+
d = {}
|
| 672 |
+
for n in G:
|
| 673 |
+
d[n] = 0
|
| 674 |
+
del n
|
| 675 |
+
# 2. Find a 1-Arborescence T^k such that k is in K(pi, d).
|
| 676 |
+
minimum_1_arborescences = k_pi()
|
| 677 |
+
while True:
|
| 678 |
+
# Reduce K(pi) to K(pi, d)
|
| 679 |
+
# Find the arborescence in K(pi) which increases the lest in
|
| 680 |
+
# direction d
|
| 681 |
+
min_k_d_weight = math.inf
|
| 682 |
+
min_k_d = None
|
| 683 |
+
for arborescence in minimum_1_arborescences:
|
| 684 |
+
weighted_cost = 0
|
| 685 |
+
for n, deg in arborescence.degree:
|
| 686 |
+
weighted_cost += d[n] * (deg - 2)
|
| 687 |
+
if weighted_cost < min_k_d_weight:
|
| 688 |
+
min_k_d_weight = weighted_cost
|
| 689 |
+
min_k_d = arborescence
|
| 690 |
+
|
| 691 |
+
# 3. If sum of d_i * v_{i, k} is greater than zero, terminate
|
| 692 |
+
if min_k_d_weight > 0:
|
| 693 |
+
return d, min_k_d
|
| 694 |
+
# 4. d_i = d_i + v_{i, k}
|
| 695 |
+
for n, deg in min_k_d.degree:
|
| 696 |
+
d[n] += deg - 2
|
| 697 |
+
# Check that we do not need to terminate because the direction
|
| 698 |
+
# of ascent does not exist. This is done with linear
|
| 699 |
+
# programming.
|
| 700 |
+
c = np.full(len(minimum_1_arborescences), -1, dtype=int)
|
| 701 |
+
a_eq = np.empty((len(G) + 1, len(minimum_1_arborescences)), dtype=int)
|
| 702 |
+
b_eq = np.zeros(len(G) + 1, dtype=int)
|
| 703 |
+
b_eq[len(G)] = 1
|
| 704 |
+
for arb_count, arborescence in enumerate(minimum_1_arborescences):
|
| 705 |
+
n_count = len(G) - 1
|
| 706 |
+
for n, deg in arborescence.degree:
|
| 707 |
+
a_eq[n_count][arb_count] = deg - 2
|
| 708 |
+
n_count -= 1
|
| 709 |
+
a_eq[len(G)][arb_count] = 1
|
| 710 |
+
program_result = sp.optimize.linprog(
|
| 711 |
+
c, A_eq=a_eq, b_eq=b_eq, method="highs-ipm"
|
| 712 |
+
)
|
| 713 |
+
# If the constants exist, then the direction of ascent doesn't
|
| 714 |
+
if program_result.success:
|
| 715 |
+
# There is no direction of ascent
|
| 716 |
+
return None, minimum_1_arborescences
|
| 717 |
+
|
| 718 |
+
# 5. GO TO 2
|
| 719 |
+
|
| 720 |
+
def find_epsilon(k, d):
|
| 721 |
+
"""
|
| 722 |
+
Given the direction of ascent at pi, find the maximum distance we can go
|
| 723 |
+
in that direction.
|
| 724 |
+
|
| 725 |
+
Parameters
|
| 726 |
+
----------
|
| 727 |
+
k_xy : set
|
| 728 |
+
The set of 1-arborescences which have the minimum rate of increase
|
| 729 |
+
in the direction of ascent
|
| 730 |
+
|
| 731 |
+
d : dict
|
| 732 |
+
The direction of ascent
|
| 733 |
+
|
| 734 |
+
Returns
|
| 735 |
+
-------
|
| 736 |
+
float
|
| 737 |
+
The distance we can travel in direction `d`
|
| 738 |
+
"""
|
| 739 |
+
min_epsilon = math.inf
|
| 740 |
+
for e_u, e_v, e_w in G.edges(data=weight):
|
| 741 |
+
if (e_u, e_v) in k.edges:
|
| 742 |
+
continue
|
| 743 |
+
# Now, I have found a condition which MUST be true for the edges to
|
| 744 |
+
# be a valid substitute. The edge in the graph which is the
|
| 745 |
+
# substitute is the one with the same terminated end. This can be
|
| 746 |
+
# checked rather simply.
|
| 747 |
+
#
|
| 748 |
+
# Find the edge within k which is the substitute. Because k is a
|
| 749 |
+
# 1-arborescence, we know that they is only one such edges
|
| 750 |
+
# leading into every vertex.
|
| 751 |
+
if len(k.in_edges(e_v, data=weight)) > 1:
|
| 752 |
+
raise Exception
|
| 753 |
+
sub_u, sub_v, sub_w = next(k.in_edges(e_v, data=weight).__iter__())
|
| 754 |
+
k.add_edge(e_u, e_v, **{weight: e_w})
|
| 755 |
+
k.remove_edge(sub_u, sub_v)
|
| 756 |
+
if (
|
| 757 |
+
max(d for n, d in k.in_degree()) <= 1
|
| 758 |
+
and len(G) == k.number_of_edges()
|
| 759 |
+
and nx.is_weakly_connected(k)
|
| 760 |
+
):
|
| 761 |
+
# Ascent method calculation
|
| 762 |
+
if d[sub_u] == d[e_u] or sub_w == e_w:
|
| 763 |
+
# Revert to the original graph
|
| 764 |
+
k.remove_edge(e_u, e_v)
|
| 765 |
+
k.add_edge(sub_u, sub_v, **{weight: sub_w})
|
| 766 |
+
continue
|
| 767 |
+
epsilon = (sub_w - e_w) / (d[e_u] - d[sub_u])
|
| 768 |
+
if 0 < epsilon < min_epsilon:
|
| 769 |
+
min_epsilon = epsilon
|
| 770 |
+
# Revert to the original graph
|
| 771 |
+
k.remove_edge(e_u, e_v)
|
| 772 |
+
k.add_edge(sub_u, sub_v, **{weight: sub_w})
|
| 773 |
+
|
| 774 |
+
return min_epsilon
|
| 775 |
+
|
| 776 |
+
# I have to know that the elements in pi correspond to the correct elements
|
| 777 |
+
# in the direction of ascent, even if the node labels are not integers.
|
| 778 |
+
# Thus, I will use dictionaries to made that mapping.
|
| 779 |
+
pi_dict = {}
|
| 780 |
+
for n in G:
|
| 781 |
+
pi_dict[n] = 0
|
| 782 |
+
del n
|
| 783 |
+
original_edge_weights = {}
|
| 784 |
+
for u, v, d in G.edges(data=True):
|
| 785 |
+
original_edge_weights[(u, v)] = d[weight]
|
| 786 |
+
dir_ascent, k_d = direction_of_ascent()
|
| 787 |
+
while dir_ascent is not None:
|
| 788 |
+
max_distance = find_epsilon(k_d, dir_ascent)
|
| 789 |
+
for n, v in dir_ascent.items():
|
| 790 |
+
pi_dict[n] += max_distance * v
|
| 791 |
+
for u, v, d in G.edges(data=True):
|
| 792 |
+
d[weight] = original_edge_weights[(u, v)] + pi_dict[u]
|
| 793 |
+
dir_ascent, k_d = direction_of_ascent()
|
| 794 |
+
nx._clear_cache(G)
|
| 795 |
+
# k_d is no longer an individual 1-arborescence but rather a set of
|
| 796 |
+
# minimal 1-arborescences at the maximum point of the polytope and should
|
| 797 |
+
# be reflected as such
|
| 798 |
+
k_max = k_d
|
| 799 |
+
|
| 800 |
+
# Search for a cycle within k_max. If a cycle exists, return it as the
|
| 801 |
+
# solution
|
| 802 |
+
for k in k_max:
|
| 803 |
+
if len([n for n in k if k.degree(n) == 2]) == G.order():
|
| 804 |
+
# Tour found
|
| 805 |
+
# TODO: this branch does not restore original_edge_weights of G!
|
| 806 |
+
return k.size(weight), k
|
| 807 |
+
|
| 808 |
+
# Write the original edge weights back to G and every member of k_max at
|
| 809 |
+
# the maximum point. Also average the number of times that edge appears in
|
| 810 |
+
# the set of minimal 1-arborescences.
|
| 811 |
+
x_star = {}
|
| 812 |
+
size_k_max = len(k_max)
|
| 813 |
+
for u, v, d in G.edges(data=True):
|
| 814 |
+
edge_count = 0
|
| 815 |
+
d[weight] = original_edge_weights[(u, v)]
|
| 816 |
+
for k in k_max:
|
| 817 |
+
if (u, v) in k.edges():
|
| 818 |
+
edge_count += 1
|
| 819 |
+
k[u][v][weight] = original_edge_weights[(u, v)]
|
| 820 |
+
x_star[(u, v)] = edge_count / size_k_max
|
| 821 |
+
# Now symmetrize the edges in x_star and scale them according to (5) in
|
| 822 |
+
# reference [1]
|
| 823 |
+
z_star = {}
|
| 824 |
+
scale_factor = (G.order() - 1) / G.order()
|
| 825 |
+
for u, v in x_star:
|
| 826 |
+
frequency = x_star[(u, v)] + x_star[(v, u)]
|
| 827 |
+
if frequency > 0:
|
| 828 |
+
z_star[(u, v)] = scale_factor * frequency
|
| 829 |
+
del x_star
|
| 830 |
+
# Return the optimal weight and the z dict
|
| 831 |
+
return next(k_max.__iter__()).size(weight), z_star
|
| 832 |
+
|
| 833 |
+
|
| 834 |
+
@nx._dispatchable
|
| 835 |
+
def spanning_tree_distribution(G, z):
|
| 836 |
+
"""
|
| 837 |
+
Find the asadpour exponential distribution of spanning trees.
|
| 838 |
+
|
| 839 |
+
Solves the Maximum Entropy Convex Program in the Asadpour algorithm [1]_
|
| 840 |
+
using the approach in section 7 to build an exponential distribution of
|
| 841 |
+
undirected spanning trees.
|
| 842 |
+
|
| 843 |
+
This algorithm ensures that the probability of any edge in a spanning
|
| 844 |
+
tree is proportional to the sum of the probabilities of the tress
|
| 845 |
+
containing that edge over the sum of the probabilities of all spanning
|
| 846 |
+
trees of the graph.
|
| 847 |
+
|
| 848 |
+
Parameters
|
| 849 |
+
----------
|
| 850 |
+
G : nx.MultiGraph
|
| 851 |
+
The undirected support graph for the Held Karp relaxation
|
| 852 |
+
|
| 853 |
+
z : dict
|
| 854 |
+
The output of `held_karp_ascent()`, a scaled version of the Held-Karp
|
| 855 |
+
solution.
|
| 856 |
+
|
| 857 |
+
Returns
|
| 858 |
+
-------
|
| 859 |
+
gamma : dict
|
| 860 |
+
The probability distribution which approximately preserves the marginal
|
| 861 |
+
probabilities of `z`.
|
| 862 |
+
"""
|
| 863 |
+
from math import exp
|
| 864 |
+
from math import log as ln
|
| 865 |
+
|
| 866 |
+
def q(e):
|
| 867 |
+
"""
|
| 868 |
+
The value of q(e) is described in the Asadpour paper is "the
|
| 869 |
+
probability that edge e will be included in a spanning tree T that is
|
| 870 |
+
chosen with probability proportional to exp(gamma(T))" which
|
| 871 |
+
basically means that it is the total probability of the edge appearing
|
| 872 |
+
across the whole distribution.
|
| 873 |
+
|
| 874 |
+
Parameters
|
| 875 |
+
----------
|
| 876 |
+
e : tuple
|
| 877 |
+
The `(u, v)` tuple describing the edge we are interested in
|
| 878 |
+
|
| 879 |
+
Returns
|
| 880 |
+
-------
|
| 881 |
+
float
|
| 882 |
+
The probability that a spanning tree chosen according to the
|
| 883 |
+
current values of gamma will include edge `e`.
|
| 884 |
+
"""
|
| 885 |
+
# Create the laplacian matrices
|
| 886 |
+
for u, v, d in G.edges(data=True):
|
| 887 |
+
d[lambda_key] = exp(gamma[(u, v)])
|
| 888 |
+
G_Kirchhoff = nx.number_of_spanning_trees(G, weight=lambda_key)
|
| 889 |
+
G_e = nx.contracted_edge(G, e, self_loops=False)
|
| 890 |
+
G_e_Kirchhoff = nx.number_of_spanning_trees(G_e, weight=lambda_key)
|
| 891 |
+
|
| 892 |
+
# Multiply by the weight of the contracted edge since it is not included
|
| 893 |
+
# in the total weight of the contracted graph.
|
| 894 |
+
return exp(gamma[(e[0], e[1])]) * G_e_Kirchhoff / G_Kirchhoff
|
| 895 |
+
|
| 896 |
+
# initialize gamma to the zero dict
|
| 897 |
+
gamma = {}
|
| 898 |
+
for u, v, _ in G.edges:
|
| 899 |
+
gamma[(u, v)] = 0
|
| 900 |
+
|
| 901 |
+
# set epsilon
|
| 902 |
+
EPSILON = 0.2
|
| 903 |
+
|
| 904 |
+
# pick an edge attribute name that is unlikely to be in the graph
|
| 905 |
+
lambda_key = "spanning_tree_distribution's secret attribute name for lambda"
|
| 906 |
+
|
| 907 |
+
while True:
|
| 908 |
+
# We need to know that know that no values of q_e are greater than
|
| 909 |
+
# (1 + epsilon) * z_e, however changing one gamma value can increase the
|
| 910 |
+
# value of a different q_e, so we have to complete the for loop without
|
| 911 |
+
# changing anything for the condition to be meet
|
| 912 |
+
in_range_count = 0
|
| 913 |
+
# Search for an edge with q_e > (1 + epsilon) * z_e
|
| 914 |
+
for u, v in gamma:
|
| 915 |
+
e = (u, v)
|
| 916 |
+
q_e = q(e)
|
| 917 |
+
z_e = z[e]
|
| 918 |
+
if q_e > (1 + EPSILON) * z_e:
|
| 919 |
+
delta = ln(
|
| 920 |
+
(q_e * (1 - (1 + EPSILON / 2) * z_e))
|
| 921 |
+
/ ((1 - q_e) * (1 + EPSILON / 2) * z_e)
|
| 922 |
+
)
|
| 923 |
+
gamma[e] -= delta
|
| 924 |
+
# Check that delta had the desired effect
|
| 925 |
+
new_q_e = q(e)
|
| 926 |
+
desired_q_e = (1 + EPSILON / 2) * z_e
|
| 927 |
+
if round(new_q_e, 8) != round(desired_q_e, 8):
|
| 928 |
+
raise nx.NetworkXError(
|
| 929 |
+
f"Unable to modify probability for edge ({u}, {v})"
|
| 930 |
+
)
|
| 931 |
+
else:
|
| 932 |
+
in_range_count += 1
|
| 933 |
+
# Check if the for loop terminated without changing any gamma
|
| 934 |
+
if in_range_count == len(gamma):
|
| 935 |
+
break
|
| 936 |
+
|
| 937 |
+
# Remove the new edge attributes
|
| 938 |
+
for _, _, d in G.edges(data=True):
|
| 939 |
+
if lambda_key in d:
|
| 940 |
+
del d[lambda_key]
|
| 941 |
+
|
| 942 |
+
return gamma
|
| 943 |
+
|
| 944 |
+
|
| 945 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 946 |
+
def greedy_tsp(G, weight="weight", source=None):
|
| 947 |
+
"""Return a low cost cycle starting at `source` and its cost.
|
| 948 |
+
|
| 949 |
+
This approximates a solution to the traveling salesman problem.
|
| 950 |
+
It finds a cycle of all the nodes that a salesman can visit in order
|
| 951 |
+
to visit many nodes while minimizing total distance.
|
| 952 |
+
It uses a simple greedy algorithm.
|
| 953 |
+
In essence, this function returns a large cycle given a source point
|
| 954 |
+
for which the total cost of the cycle is minimized.
|
| 955 |
+
|
| 956 |
+
Parameters
|
| 957 |
+
----------
|
| 958 |
+
G : Graph
|
| 959 |
+
The Graph should be a complete weighted undirected graph.
|
| 960 |
+
The distance between all pairs of nodes should be included.
|
| 961 |
+
|
| 962 |
+
weight : string, optional (default="weight")
|
| 963 |
+
Edge data key corresponding to the edge weight.
|
| 964 |
+
If any edge does not have this attribute the weight is set to 1.
|
| 965 |
+
|
| 966 |
+
source : node, optional (default: first node in list(G))
|
| 967 |
+
Starting node. If None, defaults to ``next(iter(G))``
|
| 968 |
+
|
| 969 |
+
Returns
|
| 970 |
+
-------
|
| 971 |
+
cycle : list of nodes
|
| 972 |
+
Returns the cycle (list of nodes) that a salesman
|
| 973 |
+
can follow to minimize total weight of the trip.
|
| 974 |
+
|
| 975 |
+
Raises
|
| 976 |
+
------
|
| 977 |
+
NetworkXError
|
| 978 |
+
If `G` is not complete, the algorithm raises an exception.
|
| 979 |
+
|
| 980 |
+
Examples
|
| 981 |
+
--------
|
| 982 |
+
>>> from networkx.algorithms import approximation as approx
|
| 983 |
+
>>> G = nx.DiGraph()
|
| 984 |
+
>>> G.add_weighted_edges_from(
|
| 985 |
+
... {
|
| 986 |
+
... ("A", "B", 3),
|
| 987 |
+
... ("A", "C", 17),
|
| 988 |
+
... ("A", "D", 14),
|
| 989 |
+
... ("B", "A", 3),
|
| 990 |
+
... ("B", "C", 12),
|
| 991 |
+
... ("B", "D", 16),
|
| 992 |
+
... ("C", "A", 13),
|
| 993 |
+
... ("C", "B", 12),
|
| 994 |
+
... ("C", "D", 4),
|
| 995 |
+
... ("D", "A", 14),
|
| 996 |
+
... ("D", "B", 15),
|
| 997 |
+
... ("D", "C", 2),
|
| 998 |
+
... }
|
| 999 |
+
... )
|
| 1000 |
+
>>> cycle = approx.greedy_tsp(G, source="D")
|
| 1001 |
+
>>> cost = sum(G[n][nbr]["weight"] for n, nbr in nx.utils.pairwise(cycle))
|
| 1002 |
+
>>> cycle
|
| 1003 |
+
['D', 'C', 'B', 'A', 'D']
|
| 1004 |
+
>>> cost
|
| 1005 |
+
31
|
| 1006 |
+
|
| 1007 |
+
Notes
|
| 1008 |
+
-----
|
| 1009 |
+
This implementation of a greedy algorithm is based on the following:
|
| 1010 |
+
|
| 1011 |
+
- The algorithm adds a node to the solution at every iteration.
|
| 1012 |
+
- The algorithm selects a node not already in the cycle whose connection
|
| 1013 |
+
to the previous node adds the least cost to the cycle.
|
| 1014 |
+
|
| 1015 |
+
A greedy algorithm does not always give the best solution.
|
| 1016 |
+
However, it can construct a first feasible solution which can
|
| 1017 |
+
be passed as a parameter to an iterative improvement algorithm such
|
| 1018 |
+
as Simulated Annealing, or Threshold Accepting.
|
| 1019 |
+
|
| 1020 |
+
Time complexity: It has a running time $O(|V|^2)$
|
| 1021 |
+
"""
|
| 1022 |
+
# Check that G is a complete graph
|
| 1023 |
+
N = len(G) - 1
|
| 1024 |
+
# This check ignores selfloops which is what we want here.
|
| 1025 |
+
if any(len(nbrdict) - (n in nbrdict) != N for n, nbrdict in G.adj.items()):
|
| 1026 |
+
raise nx.NetworkXError("G must be a complete graph.")
|
| 1027 |
+
|
| 1028 |
+
if source is None:
|
| 1029 |
+
source = nx.utils.arbitrary_element(G)
|
| 1030 |
+
|
| 1031 |
+
if G.number_of_nodes() == 2:
|
| 1032 |
+
neighbor = next(G.neighbors(source))
|
| 1033 |
+
return [source, neighbor, source]
|
| 1034 |
+
|
| 1035 |
+
nodeset = set(G)
|
| 1036 |
+
nodeset.remove(source)
|
| 1037 |
+
cycle = [source]
|
| 1038 |
+
next_node = source
|
| 1039 |
+
while nodeset:
|
| 1040 |
+
nbrdict = G[next_node]
|
| 1041 |
+
next_node = min(nodeset, key=lambda n: nbrdict[n].get(weight, 1))
|
| 1042 |
+
cycle.append(next_node)
|
| 1043 |
+
nodeset.remove(next_node)
|
| 1044 |
+
cycle.append(cycle[0])
|
| 1045 |
+
return cycle
|
| 1046 |
+
|
| 1047 |
+
|
| 1048 |
+
@py_random_state(9)
|
| 1049 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 1050 |
+
def simulated_annealing_tsp(
|
| 1051 |
+
G,
|
| 1052 |
+
init_cycle,
|
| 1053 |
+
weight="weight",
|
| 1054 |
+
source=None,
|
| 1055 |
+
temp=100,
|
| 1056 |
+
move="1-1",
|
| 1057 |
+
max_iterations=10,
|
| 1058 |
+
N_inner=100,
|
| 1059 |
+
alpha=0.01,
|
| 1060 |
+
seed=None,
|
| 1061 |
+
):
|
| 1062 |
+
"""Returns an approximate solution to the traveling salesman problem.
|
| 1063 |
+
|
| 1064 |
+
This function uses simulated annealing to approximate the minimal cost
|
| 1065 |
+
cycle through the nodes. Starting from a suboptimal solution, simulated
|
| 1066 |
+
annealing perturbs that solution, occasionally accepting changes that make
|
| 1067 |
+
the solution worse to escape from a locally optimal solution. The chance
|
| 1068 |
+
of accepting such changes decreases over the iterations to encourage
|
| 1069 |
+
an optimal result. In summary, the function returns a cycle starting
|
| 1070 |
+
at `source` for which the total cost is minimized. It also returns the cost.
|
| 1071 |
+
|
| 1072 |
+
The chance of accepting a proposed change is related to a parameter called
|
| 1073 |
+
the temperature (annealing has a physical analogue of steel hardening
|
| 1074 |
+
as it cools). As the temperature is reduced, the chance of moves that
|
| 1075 |
+
increase cost goes down.
|
| 1076 |
+
|
| 1077 |
+
Parameters
|
| 1078 |
+
----------
|
| 1079 |
+
G : Graph
|
| 1080 |
+
`G` should be a complete weighted graph.
|
| 1081 |
+
The distance between all pairs of nodes should be included.
|
| 1082 |
+
|
| 1083 |
+
init_cycle : list of all nodes or "greedy"
|
| 1084 |
+
The initial solution (a cycle through all nodes returning to the start).
|
| 1085 |
+
This argument has no default to make you think about it.
|
| 1086 |
+
If "greedy", use `greedy_tsp(G, weight)`.
|
| 1087 |
+
Other common starting cycles are `list(G) + [next(iter(G))]` or the final
|
| 1088 |
+
result of `simulated_annealing_tsp` when doing `threshold_accepting_tsp`.
|
| 1089 |
+
|
| 1090 |
+
weight : string, optional (default="weight")
|
| 1091 |
+
Edge data key corresponding to the edge weight.
|
| 1092 |
+
If any edge does not have this attribute the weight is set to 1.
|
| 1093 |
+
|
| 1094 |
+
source : node, optional (default: first node in list(G))
|
| 1095 |
+
Starting node. If None, defaults to ``next(iter(G))``
|
| 1096 |
+
|
| 1097 |
+
temp : int, optional (default=100)
|
| 1098 |
+
The algorithm's temperature parameter. It represents the initial
|
| 1099 |
+
value of temperature
|
| 1100 |
+
|
| 1101 |
+
move : "1-1" or "1-0" or function, optional (default="1-1")
|
| 1102 |
+
Indicator of what move to use when finding new trial solutions.
|
| 1103 |
+
Strings indicate two special built-in moves:
|
| 1104 |
+
|
| 1105 |
+
- "1-1": 1-1 exchange which transposes the position
|
| 1106 |
+
of two elements of the current solution.
|
| 1107 |
+
The function called is :func:`swap_two_nodes`.
|
| 1108 |
+
For example if we apply 1-1 exchange in the solution
|
| 1109 |
+
``A = [3, 2, 1, 4, 3]``
|
| 1110 |
+
we can get the following by the transposition of 1 and 4 elements:
|
| 1111 |
+
``A' = [3, 2, 4, 1, 3]``
|
| 1112 |
+
- "1-0": 1-0 exchange which moves an node in the solution
|
| 1113 |
+
to a new position.
|
| 1114 |
+
The function called is :func:`move_one_node`.
|
| 1115 |
+
For example if we apply 1-0 exchange in the solution
|
| 1116 |
+
``A = [3, 2, 1, 4, 3]``
|
| 1117 |
+
we can transfer the fourth element to the second position:
|
| 1118 |
+
``A' = [3, 4, 2, 1, 3]``
|
| 1119 |
+
|
| 1120 |
+
You may provide your own functions to enact a move from
|
| 1121 |
+
one solution to a neighbor solution. The function must take
|
| 1122 |
+
the solution as input along with a `seed` input to control
|
| 1123 |
+
random number generation (see the `seed` input here).
|
| 1124 |
+
Your function should maintain the solution as a cycle with
|
| 1125 |
+
equal first and last node and all others appearing once.
|
| 1126 |
+
Your function should return the new solution.
|
| 1127 |
+
|
| 1128 |
+
max_iterations : int, optional (default=10)
|
| 1129 |
+
Declared done when this number of consecutive iterations of
|
| 1130 |
+
the outer loop occurs without any change in the best cost solution.
|
| 1131 |
+
|
| 1132 |
+
N_inner : int, optional (default=100)
|
| 1133 |
+
The number of iterations of the inner loop.
|
| 1134 |
+
|
| 1135 |
+
alpha : float between (0, 1), optional (default=0.01)
|
| 1136 |
+
Percentage of temperature decrease in each iteration
|
| 1137 |
+
of outer loop
|
| 1138 |
+
|
| 1139 |
+
seed : integer, random_state, or None (default)
|
| 1140 |
+
Indicator of random number generation state.
|
| 1141 |
+
See :ref:`Randomness<randomness>`.
|
| 1142 |
+
|
| 1143 |
+
Returns
|
| 1144 |
+
-------
|
| 1145 |
+
cycle : list of nodes
|
| 1146 |
+
Returns the cycle (list of nodes) that a salesman
|
| 1147 |
+
can follow to minimize total weight of the trip.
|
| 1148 |
+
|
| 1149 |
+
Raises
|
| 1150 |
+
------
|
| 1151 |
+
NetworkXError
|
| 1152 |
+
If `G` is not complete the algorithm raises an exception.
|
| 1153 |
+
|
| 1154 |
+
Examples
|
| 1155 |
+
--------
|
| 1156 |
+
>>> from networkx.algorithms import approximation as approx
|
| 1157 |
+
>>> G = nx.DiGraph()
|
| 1158 |
+
>>> G.add_weighted_edges_from(
|
| 1159 |
+
... {
|
| 1160 |
+
... ("A", "B", 3),
|
| 1161 |
+
... ("A", "C", 17),
|
| 1162 |
+
... ("A", "D", 14),
|
| 1163 |
+
... ("B", "A", 3),
|
| 1164 |
+
... ("B", "C", 12),
|
| 1165 |
+
... ("B", "D", 16),
|
| 1166 |
+
... ("C", "A", 13),
|
| 1167 |
+
... ("C", "B", 12),
|
| 1168 |
+
... ("C", "D", 4),
|
| 1169 |
+
... ("D", "A", 14),
|
| 1170 |
+
... ("D", "B", 15),
|
| 1171 |
+
... ("D", "C", 2),
|
| 1172 |
+
... }
|
| 1173 |
+
... )
|
| 1174 |
+
>>> cycle = approx.simulated_annealing_tsp(G, "greedy", source="D")
|
| 1175 |
+
>>> cost = sum(G[n][nbr]["weight"] for n, nbr in nx.utils.pairwise(cycle))
|
| 1176 |
+
>>> cycle
|
| 1177 |
+
['D', 'C', 'B', 'A', 'D']
|
| 1178 |
+
>>> cost
|
| 1179 |
+
31
|
| 1180 |
+
>>> incycle = ["D", "B", "A", "C", "D"]
|
| 1181 |
+
>>> cycle = approx.simulated_annealing_tsp(G, incycle, source="D")
|
| 1182 |
+
>>> cost = sum(G[n][nbr]["weight"] for n, nbr in nx.utils.pairwise(cycle))
|
| 1183 |
+
>>> cycle
|
| 1184 |
+
['D', 'C', 'B', 'A', 'D']
|
| 1185 |
+
>>> cost
|
| 1186 |
+
31
|
| 1187 |
+
|
| 1188 |
+
Notes
|
| 1189 |
+
-----
|
| 1190 |
+
Simulated Annealing is a metaheuristic local search algorithm.
|
| 1191 |
+
The main characteristic of this algorithm is that it accepts
|
| 1192 |
+
even solutions which lead to the increase of the cost in order
|
| 1193 |
+
to escape from low quality local optimal solutions.
|
| 1194 |
+
|
| 1195 |
+
This algorithm needs an initial solution. If not provided, it is
|
| 1196 |
+
constructed by a simple greedy algorithm. At every iteration, the
|
| 1197 |
+
algorithm selects thoughtfully a neighbor solution.
|
| 1198 |
+
Consider $c(x)$ cost of current solution and $c(x')$ cost of a
|
| 1199 |
+
neighbor solution.
|
| 1200 |
+
If $c(x') - c(x) <= 0$ then the neighbor solution becomes the current
|
| 1201 |
+
solution for the next iteration. Otherwise, the algorithm accepts
|
| 1202 |
+
the neighbor solution with probability $p = exp - ([c(x') - c(x)] / temp)$.
|
| 1203 |
+
Otherwise the current solution is retained.
|
| 1204 |
+
|
| 1205 |
+
`temp` is a parameter of the algorithm and represents temperature.
|
| 1206 |
+
|
| 1207 |
+
Time complexity:
|
| 1208 |
+
For $N_i$ iterations of the inner loop and $N_o$ iterations of the
|
| 1209 |
+
outer loop, this algorithm has running time $O(N_i * N_o * |V|)$.
|
| 1210 |
+
|
| 1211 |
+
For more information and how the algorithm is inspired see:
|
| 1212 |
+
http://en.wikipedia.org/wiki/Simulated_annealing
|
| 1213 |
+
"""
|
| 1214 |
+
if move == "1-1":
|
| 1215 |
+
move = swap_two_nodes
|
| 1216 |
+
elif move == "1-0":
|
| 1217 |
+
move = move_one_node
|
| 1218 |
+
if init_cycle == "greedy":
|
| 1219 |
+
# Construct an initial solution using a greedy algorithm.
|
| 1220 |
+
cycle = greedy_tsp(G, weight=weight, source=source)
|
| 1221 |
+
if G.number_of_nodes() == 2:
|
| 1222 |
+
return cycle
|
| 1223 |
+
|
| 1224 |
+
else:
|
| 1225 |
+
cycle = list(init_cycle)
|
| 1226 |
+
if source is None:
|
| 1227 |
+
source = cycle[0]
|
| 1228 |
+
elif source != cycle[0]:
|
| 1229 |
+
raise nx.NetworkXError("source must be first node in init_cycle")
|
| 1230 |
+
if cycle[0] != cycle[-1]:
|
| 1231 |
+
raise nx.NetworkXError("init_cycle must be a cycle. (return to start)")
|
| 1232 |
+
|
| 1233 |
+
if len(cycle) - 1 != len(G) or len(set(G.nbunch_iter(cycle))) != len(G):
|
| 1234 |
+
raise nx.NetworkXError("init_cycle should be a cycle over all nodes in G.")
|
| 1235 |
+
|
| 1236 |
+
# Check that G is a complete graph
|
| 1237 |
+
N = len(G) - 1
|
| 1238 |
+
# This check ignores selfloops which is what we want here.
|
| 1239 |
+
if any(len(nbrdict) - (n in nbrdict) != N for n, nbrdict in G.adj.items()):
|
| 1240 |
+
raise nx.NetworkXError("G must be a complete graph.")
|
| 1241 |
+
|
| 1242 |
+
if G.number_of_nodes() == 2:
|
| 1243 |
+
neighbor = next(G.neighbors(source))
|
| 1244 |
+
return [source, neighbor, source]
|
| 1245 |
+
|
| 1246 |
+
# Find the cost of initial solution
|
| 1247 |
+
cost = sum(G[u][v].get(weight, 1) for u, v in pairwise(cycle))
|
| 1248 |
+
|
| 1249 |
+
count = 0
|
| 1250 |
+
best_cycle = cycle.copy()
|
| 1251 |
+
best_cost = cost
|
| 1252 |
+
while count <= max_iterations and temp > 0:
|
| 1253 |
+
count += 1
|
| 1254 |
+
for i in range(N_inner):
|
| 1255 |
+
adj_sol = move(cycle, seed)
|
| 1256 |
+
adj_cost = sum(G[u][v].get(weight, 1) for u, v in pairwise(adj_sol))
|
| 1257 |
+
delta = adj_cost - cost
|
| 1258 |
+
if delta <= 0:
|
| 1259 |
+
# Set current solution the adjacent solution.
|
| 1260 |
+
cycle = adj_sol
|
| 1261 |
+
cost = adj_cost
|
| 1262 |
+
|
| 1263 |
+
if cost < best_cost:
|
| 1264 |
+
count = 0
|
| 1265 |
+
best_cycle = cycle.copy()
|
| 1266 |
+
best_cost = cost
|
| 1267 |
+
else:
|
| 1268 |
+
# Accept even a worse solution with probability p.
|
| 1269 |
+
p = math.exp(-delta / temp)
|
| 1270 |
+
if p >= seed.random():
|
| 1271 |
+
cycle = adj_sol
|
| 1272 |
+
cost = adj_cost
|
| 1273 |
+
temp -= temp * alpha
|
| 1274 |
+
|
| 1275 |
+
return best_cycle
|
| 1276 |
+
|
| 1277 |
+
|
| 1278 |
+
@py_random_state(9)
|
| 1279 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 1280 |
+
def threshold_accepting_tsp(
|
| 1281 |
+
G,
|
| 1282 |
+
init_cycle,
|
| 1283 |
+
weight="weight",
|
| 1284 |
+
source=None,
|
| 1285 |
+
threshold=1,
|
| 1286 |
+
move="1-1",
|
| 1287 |
+
max_iterations=10,
|
| 1288 |
+
N_inner=100,
|
| 1289 |
+
alpha=0.1,
|
| 1290 |
+
seed=None,
|
| 1291 |
+
):
|
| 1292 |
+
"""Returns an approximate solution to the traveling salesman problem.
|
| 1293 |
+
|
| 1294 |
+
This function uses threshold accepting methods to approximate the minimal cost
|
| 1295 |
+
cycle through the nodes. Starting from a suboptimal solution, threshold
|
| 1296 |
+
accepting methods perturb that solution, accepting any changes that make
|
| 1297 |
+
the solution no worse than increasing by a threshold amount. Improvements
|
| 1298 |
+
in cost are accepted, but so are changes leading to small increases in cost.
|
| 1299 |
+
This allows the solution to leave suboptimal local minima in solution space.
|
| 1300 |
+
The threshold is decreased slowly as iterations proceed helping to ensure
|
| 1301 |
+
an optimum. In summary, the function returns a cycle starting at `source`
|
| 1302 |
+
for which the total cost is minimized.
|
| 1303 |
+
|
| 1304 |
+
Parameters
|
| 1305 |
+
----------
|
| 1306 |
+
G : Graph
|
| 1307 |
+
`G` should be a complete weighted graph.
|
| 1308 |
+
The distance between all pairs of nodes should be included.
|
| 1309 |
+
|
| 1310 |
+
init_cycle : list or "greedy"
|
| 1311 |
+
The initial solution (a cycle through all nodes returning to the start).
|
| 1312 |
+
This argument has no default to make you think about it.
|
| 1313 |
+
If "greedy", use `greedy_tsp(G, weight)`.
|
| 1314 |
+
Other common starting cycles are `list(G) + [next(iter(G))]` or the final
|
| 1315 |
+
result of `simulated_annealing_tsp` when doing `threshold_accepting_tsp`.
|
| 1316 |
+
|
| 1317 |
+
weight : string, optional (default="weight")
|
| 1318 |
+
Edge data key corresponding to the edge weight.
|
| 1319 |
+
If any edge does not have this attribute the weight is set to 1.
|
| 1320 |
+
|
| 1321 |
+
source : node, optional (default: first node in list(G))
|
| 1322 |
+
Starting node. If None, defaults to ``next(iter(G))``
|
| 1323 |
+
|
| 1324 |
+
threshold : int, optional (default=1)
|
| 1325 |
+
The algorithm's threshold parameter. It represents the initial
|
| 1326 |
+
threshold's value
|
| 1327 |
+
|
| 1328 |
+
move : "1-1" or "1-0" or function, optional (default="1-1")
|
| 1329 |
+
Indicator of what move to use when finding new trial solutions.
|
| 1330 |
+
Strings indicate two special built-in moves:
|
| 1331 |
+
|
| 1332 |
+
- "1-1": 1-1 exchange which transposes the position
|
| 1333 |
+
of two elements of the current solution.
|
| 1334 |
+
The function called is :func:`swap_two_nodes`.
|
| 1335 |
+
For example if we apply 1-1 exchange in the solution
|
| 1336 |
+
``A = [3, 2, 1, 4, 3]``
|
| 1337 |
+
we can get the following by the transposition of 1 and 4 elements:
|
| 1338 |
+
``A' = [3, 2, 4, 1, 3]``
|
| 1339 |
+
- "1-0": 1-0 exchange which moves an node in the solution
|
| 1340 |
+
to a new position.
|
| 1341 |
+
The function called is :func:`move_one_node`.
|
| 1342 |
+
For example if we apply 1-0 exchange in the solution
|
| 1343 |
+
``A = [3, 2, 1, 4, 3]``
|
| 1344 |
+
we can transfer the fourth element to the second position:
|
| 1345 |
+
``A' = [3, 4, 2, 1, 3]``
|
| 1346 |
+
|
| 1347 |
+
You may provide your own functions to enact a move from
|
| 1348 |
+
one solution to a neighbor solution. The function must take
|
| 1349 |
+
the solution as input along with a `seed` input to control
|
| 1350 |
+
random number generation (see the `seed` input here).
|
| 1351 |
+
Your function should maintain the solution as a cycle with
|
| 1352 |
+
equal first and last node and all others appearing once.
|
| 1353 |
+
Your function should return the new solution.
|
| 1354 |
+
|
| 1355 |
+
max_iterations : int, optional (default=10)
|
| 1356 |
+
Declared done when this number of consecutive iterations of
|
| 1357 |
+
the outer loop occurs without any change in the best cost solution.
|
| 1358 |
+
|
| 1359 |
+
N_inner : int, optional (default=100)
|
| 1360 |
+
The number of iterations of the inner loop.
|
| 1361 |
+
|
| 1362 |
+
alpha : float between (0, 1), optional (default=0.1)
|
| 1363 |
+
Percentage of threshold decrease when there is at
|
| 1364 |
+
least one acceptance of a neighbor solution.
|
| 1365 |
+
If no inner loop moves are accepted the threshold remains unchanged.
|
| 1366 |
+
|
| 1367 |
+
seed : integer, random_state, or None (default)
|
| 1368 |
+
Indicator of random number generation state.
|
| 1369 |
+
See :ref:`Randomness<randomness>`.
|
| 1370 |
+
|
| 1371 |
+
Returns
|
| 1372 |
+
-------
|
| 1373 |
+
cycle : list of nodes
|
| 1374 |
+
Returns the cycle (list of nodes) that a salesman
|
| 1375 |
+
can follow to minimize total weight of the trip.
|
| 1376 |
+
|
| 1377 |
+
Raises
|
| 1378 |
+
------
|
| 1379 |
+
NetworkXError
|
| 1380 |
+
If `G` is not complete the algorithm raises an exception.
|
| 1381 |
+
|
| 1382 |
+
Examples
|
| 1383 |
+
--------
|
| 1384 |
+
>>> from networkx.algorithms import approximation as approx
|
| 1385 |
+
>>> G = nx.DiGraph()
|
| 1386 |
+
>>> G.add_weighted_edges_from(
|
| 1387 |
+
... {
|
| 1388 |
+
... ("A", "B", 3),
|
| 1389 |
+
... ("A", "C", 17),
|
| 1390 |
+
... ("A", "D", 14),
|
| 1391 |
+
... ("B", "A", 3),
|
| 1392 |
+
... ("B", "C", 12),
|
| 1393 |
+
... ("B", "D", 16),
|
| 1394 |
+
... ("C", "A", 13),
|
| 1395 |
+
... ("C", "B", 12),
|
| 1396 |
+
... ("C", "D", 4),
|
| 1397 |
+
... ("D", "A", 14),
|
| 1398 |
+
... ("D", "B", 15),
|
| 1399 |
+
... ("D", "C", 2),
|
| 1400 |
+
... }
|
| 1401 |
+
... )
|
| 1402 |
+
>>> cycle = approx.threshold_accepting_tsp(G, "greedy", source="D")
|
| 1403 |
+
>>> cost = sum(G[n][nbr]["weight"] for n, nbr in nx.utils.pairwise(cycle))
|
| 1404 |
+
>>> cycle
|
| 1405 |
+
['D', 'C', 'B', 'A', 'D']
|
| 1406 |
+
>>> cost
|
| 1407 |
+
31
|
| 1408 |
+
>>> incycle = ["D", "B", "A", "C", "D"]
|
| 1409 |
+
>>> cycle = approx.threshold_accepting_tsp(G, incycle, source="D")
|
| 1410 |
+
>>> cost = sum(G[n][nbr]["weight"] for n, nbr in nx.utils.pairwise(cycle))
|
| 1411 |
+
>>> cycle
|
| 1412 |
+
['D', 'C', 'B', 'A', 'D']
|
| 1413 |
+
>>> cost
|
| 1414 |
+
31
|
| 1415 |
+
|
| 1416 |
+
Notes
|
| 1417 |
+
-----
|
| 1418 |
+
Threshold Accepting is a metaheuristic local search algorithm.
|
| 1419 |
+
The main characteristic of this algorithm is that it accepts
|
| 1420 |
+
even solutions which lead to the increase of the cost in order
|
| 1421 |
+
to escape from low quality local optimal solutions.
|
| 1422 |
+
|
| 1423 |
+
This algorithm needs an initial solution. This solution can be
|
| 1424 |
+
constructed by a simple greedy algorithm. At every iteration, it
|
| 1425 |
+
selects thoughtfully a neighbor solution.
|
| 1426 |
+
Consider $c(x)$ cost of current solution and $c(x')$ cost of
|
| 1427 |
+
neighbor solution.
|
| 1428 |
+
If $c(x') - c(x) <= threshold$ then the neighbor solution becomes the current
|
| 1429 |
+
solution for the next iteration, where the threshold is named threshold.
|
| 1430 |
+
|
| 1431 |
+
In comparison to the Simulated Annealing algorithm, the Threshold
|
| 1432 |
+
Accepting algorithm does not accept very low quality solutions
|
| 1433 |
+
(due to the presence of the threshold value). In the case of
|
| 1434 |
+
Simulated Annealing, even a very low quality solution can
|
| 1435 |
+
be accepted with probability $p$.
|
| 1436 |
+
|
| 1437 |
+
Time complexity:
|
| 1438 |
+
It has a running time $O(m * n * |V|)$ where $m$ and $n$ are the number
|
| 1439 |
+
of times the outer and inner loop run respectively.
|
| 1440 |
+
|
| 1441 |
+
For more information and how algorithm is inspired see:
|
| 1442 |
+
https://doi.org/10.1016/0021-9991(90)90201-B
|
| 1443 |
+
|
| 1444 |
+
See Also
|
| 1445 |
+
--------
|
| 1446 |
+
simulated_annealing_tsp
|
| 1447 |
+
|
| 1448 |
+
"""
|
| 1449 |
+
if move == "1-1":
|
| 1450 |
+
move = swap_two_nodes
|
| 1451 |
+
elif move == "1-0":
|
| 1452 |
+
move = move_one_node
|
| 1453 |
+
if init_cycle == "greedy":
|
| 1454 |
+
# Construct an initial solution using a greedy algorithm.
|
| 1455 |
+
cycle = greedy_tsp(G, weight=weight, source=source)
|
| 1456 |
+
if G.number_of_nodes() == 2:
|
| 1457 |
+
return cycle
|
| 1458 |
+
|
| 1459 |
+
else:
|
| 1460 |
+
cycle = list(init_cycle)
|
| 1461 |
+
if source is None:
|
| 1462 |
+
source = cycle[0]
|
| 1463 |
+
elif source != cycle[0]:
|
| 1464 |
+
raise nx.NetworkXError("source must be first node in init_cycle")
|
| 1465 |
+
if cycle[0] != cycle[-1]:
|
| 1466 |
+
raise nx.NetworkXError("init_cycle must be a cycle. (return to start)")
|
| 1467 |
+
|
| 1468 |
+
if len(cycle) - 1 != len(G) or len(set(G.nbunch_iter(cycle))) != len(G):
|
| 1469 |
+
raise nx.NetworkXError("init_cycle is not all and only nodes.")
|
| 1470 |
+
|
| 1471 |
+
# Check that G is a complete graph
|
| 1472 |
+
N = len(G) - 1
|
| 1473 |
+
# This check ignores selfloops which is what we want here.
|
| 1474 |
+
if any(len(nbrdict) - (n in nbrdict) != N for n, nbrdict in G.adj.items()):
|
| 1475 |
+
raise nx.NetworkXError("G must be a complete graph.")
|
| 1476 |
+
|
| 1477 |
+
if G.number_of_nodes() == 2:
|
| 1478 |
+
neighbor = list(G.neighbors(source))[0]
|
| 1479 |
+
return [source, neighbor, source]
|
| 1480 |
+
|
| 1481 |
+
# Find the cost of initial solution
|
| 1482 |
+
cost = sum(G[u][v].get(weight, 1) for u, v in pairwise(cycle))
|
| 1483 |
+
|
| 1484 |
+
count = 0
|
| 1485 |
+
best_cycle = cycle.copy()
|
| 1486 |
+
best_cost = cost
|
| 1487 |
+
while count <= max_iterations:
|
| 1488 |
+
count += 1
|
| 1489 |
+
accepted = False
|
| 1490 |
+
for i in range(N_inner):
|
| 1491 |
+
adj_sol = move(cycle, seed)
|
| 1492 |
+
adj_cost = sum(G[u][v].get(weight, 1) for u, v in pairwise(adj_sol))
|
| 1493 |
+
delta = adj_cost - cost
|
| 1494 |
+
if delta <= threshold:
|
| 1495 |
+
accepted = True
|
| 1496 |
+
|
| 1497 |
+
# Set current solution the adjacent solution.
|
| 1498 |
+
cycle = adj_sol
|
| 1499 |
+
cost = adj_cost
|
| 1500 |
+
|
| 1501 |
+
if cost < best_cost:
|
| 1502 |
+
count = 0
|
| 1503 |
+
best_cycle = cycle.copy()
|
| 1504 |
+
best_cost = cost
|
| 1505 |
+
if accepted:
|
| 1506 |
+
threshold -= threshold * alpha
|
| 1507 |
+
|
| 1508 |
+
return best_cycle
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/treewidth.py
ADDED
|
@@ -0,0 +1,255 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for computing treewidth decomposition.
|
| 2 |
+
|
| 3 |
+
Treewidth of an undirected graph is a number associated with the graph.
|
| 4 |
+
It can be defined as the size of the largest vertex set (bag) in a tree
|
| 5 |
+
decomposition of the graph minus one.
|
| 6 |
+
|
| 7 |
+
`Wikipedia: Treewidth <https://en.wikipedia.org/wiki/Treewidth>`_
|
| 8 |
+
|
| 9 |
+
The notions of treewidth and tree decomposition have gained their
|
| 10 |
+
attractiveness partly because many graph and network problems that are
|
| 11 |
+
intractable (e.g., NP-hard) on arbitrary graphs become efficiently
|
| 12 |
+
solvable (e.g., with a linear time algorithm) when the treewidth of the
|
| 13 |
+
input graphs is bounded by a constant [1]_ [2]_.
|
| 14 |
+
|
| 15 |
+
There are two different functions for computing a tree decomposition:
|
| 16 |
+
:func:`treewidth_min_degree` and :func:`treewidth_min_fill_in`.
|
| 17 |
+
|
| 18 |
+
.. [1] Hans L. Bodlaender and Arie M. C. A. Koster. 2010. "Treewidth
|
| 19 |
+
computations I.Upper bounds". Inf. Comput. 208, 3 (March 2010),259-275.
|
| 20 |
+
http://dx.doi.org/10.1016/j.ic.2009.03.008
|
| 21 |
+
|
| 22 |
+
.. [2] Hans L. Bodlaender. "Discovering Treewidth". Institute of Information
|
| 23 |
+
and Computing Sciences, Utrecht University.
|
| 24 |
+
Technical Report UU-CS-2005-018.
|
| 25 |
+
http://www.cs.uu.nl
|
| 26 |
+
|
| 27 |
+
.. [3] K. Wang, Z. Lu, and J. Hicks *Treewidth*.
|
| 28 |
+
https://web.archive.org/web/20210507025929/http://web.eecs.utk.edu/~cphill25/cs594_spring2015_projects/treewidth.pdf
|
| 29 |
+
|
| 30 |
+
"""
|
| 31 |
+
|
| 32 |
+
import itertools
|
| 33 |
+
import sys
|
| 34 |
+
from heapq import heapify, heappop, heappush
|
| 35 |
+
|
| 36 |
+
import networkx as nx
|
| 37 |
+
from networkx.utils import not_implemented_for
|
| 38 |
+
|
| 39 |
+
__all__ = ["treewidth_min_degree", "treewidth_min_fill_in"]
|
| 40 |
+
|
| 41 |
+
|
| 42 |
+
@not_implemented_for("directed")
|
| 43 |
+
@not_implemented_for("multigraph")
|
| 44 |
+
@nx._dispatchable(returns_graph=True)
|
| 45 |
+
def treewidth_min_degree(G):
|
| 46 |
+
"""Returns a treewidth decomposition using the Minimum Degree heuristic.
|
| 47 |
+
|
| 48 |
+
The heuristic chooses the nodes according to their degree, i.e., first
|
| 49 |
+
the node with the lowest degree is chosen, then the graph is updated
|
| 50 |
+
and the corresponding node is removed. Next, a new node with the lowest
|
| 51 |
+
degree is chosen, and so on.
|
| 52 |
+
|
| 53 |
+
Parameters
|
| 54 |
+
----------
|
| 55 |
+
G : NetworkX graph
|
| 56 |
+
|
| 57 |
+
Returns
|
| 58 |
+
-------
|
| 59 |
+
Treewidth decomposition : (int, Graph) tuple
|
| 60 |
+
2-tuple with treewidth and the corresponding decomposed tree.
|
| 61 |
+
"""
|
| 62 |
+
deg_heuristic = MinDegreeHeuristic(G)
|
| 63 |
+
return treewidth_decomp(G, lambda graph: deg_heuristic.best_node(graph))
|
| 64 |
+
|
| 65 |
+
|
| 66 |
+
@not_implemented_for("directed")
|
| 67 |
+
@not_implemented_for("multigraph")
|
| 68 |
+
@nx._dispatchable(returns_graph=True)
|
| 69 |
+
def treewidth_min_fill_in(G):
|
| 70 |
+
"""Returns a treewidth decomposition using the Minimum Fill-in heuristic.
|
| 71 |
+
|
| 72 |
+
The heuristic chooses a node from the graph, where the number of edges
|
| 73 |
+
added turning the neighborhood of the chosen node into clique is as
|
| 74 |
+
small as possible.
|
| 75 |
+
|
| 76 |
+
Parameters
|
| 77 |
+
----------
|
| 78 |
+
G : NetworkX graph
|
| 79 |
+
|
| 80 |
+
Returns
|
| 81 |
+
-------
|
| 82 |
+
Treewidth decomposition : (int, Graph) tuple
|
| 83 |
+
2-tuple with treewidth and the corresponding decomposed tree.
|
| 84 |
+
"""
|
| 85 |
+
return treewidth_decomp(G, min_fill_in_heuristic)
|
| 86 |
+
|
| 87 |
+
|
| 88 |
+
class MinDegreeHeuristic:
|
| 89 |
+
"""Implements the Minimum Degree heuristic.
|
| 90 |
+
|
| 91 |
+
The heuristic chooses the nodes according to their degree
|
| 92 |
+
(number of neighbors), i.e., first the node with the lowest degree is
|
| 93 |
+
chosen, then the graph is updated and the corresponding node is
|
| 94 |
+
removed. Next, a new node with the lowest degree is chosen, and so on.
|
| 95 |
+
"""
|
| 96 |
+
|
| 97 |
+
def __init__(self, graph):
|
| 98 |
+
self._graph = graph
|
| 99 |
+
|
| 100 |
+
# nodes that have to be updated in the heap before each iteration
|
| 101 |
+
self._update_nodes = []
|
| 102 |
+
|
| 103 |
+
self._degreeq = [] # a heapq with 3-tuples (degree,unique_id,node)
|
| 104 |
+
self.count = itertools.count()
|
| 105 |
+
|
| 106 |
+
# build heap with initial degrees
|
| 107 |
+
for n in graph:
|
| 108 |
+
self._degreeq.append((len(graph[n]), next(self.count), n))
|
| 109 |
+
heapify(self._degreeq)
|
| 110 |
+
|
| 111 |
+
def best_node(self, graph):
|
| 112 |
+
# update nodes in self._update_nodes
|
| 113 |
+
for n in self._update_nodes:
|
| 114 |
+
# insert changed degrees into degreeq
|
| 115 |
+
heappush(self._degreeq, (len(graph[n]), next(self.count), n))
|
| 116 |
+
|
| 117 |
+
# get the next valid (minimum degree) node
|
| 118 |
+
while self._degreeq:
|
| 119 |
+
(min_degree, _, elim_node) = heappop(self._degreeq)
|
| 120 |
+
if elim_node not in graph or len(graph[elim_node]) != min_degree:
|
| 121 |
+
# outdated entry in degreeq
|
| 122 |
+
continue
|
| 123 |
+
elif min_degree == len(graph) - 1:
|
| 124 |
+
# fully connected: abort condition
|
| 125 |
+
return None
|
| 126 |
+
|
| 127 |
+
# remember to update nodes in the heap before getting the next node
|
| 128 |
+
self._update_nodes = graph[elim_node]
|
| 129 |
+
return elim_node
|
| 130 |
+
|
| 131 |
+
# the heap is empty: abort
|
| 132 |
+
return None
|
| 133 |
+
|
| 134 |
+
|
| 135 |
+
def min_fill_in_heuristic(graph_dict):
|
| 136 |
+
"""Implements the Minimum Degree heuristic.
|
| 137 |
+
|
| 138 |
+
graph_dict: dict keyed by node to sets of neighbors (no self-loops)
|
| 139 |
+
|
| 140 |
+
Returns the node from the graph, where the number of edges added when
|
| 141 |
+
turning the neighborhood of the chosen node into clique is as small as
|
| 142 |
+
possible. This algorithm chooses the nodes using the Minimum Fill-In
|
| 143 |
+
heuristic. The running time of the algorithm is :math:`O(V^3)` and it uses
|
| 144 |
+
additional constant memory.
|
| 145 |
+
"""
|
| 146 |
+
|
| 147 |
+
if len(graph_dict) == 0:
|
| 148 |
+
return None
|
| 149 |
+
|
| 150 |
+
min_fill_in_node = None
|
| 151 |
+
|
| 152 |
+
min_fill_in = sys.maxsize
|
| 153 |
+
|
| 154 |
+
# sort nodes by degree
|
| 155 |
+
nodes_by_degree = sorted(graph_dict, key=lambda x: len(graph_dict[x]))
|
| 156 |
+
min_degree = len(graph_dict[nodes_by_degree[0]])
|
| 157 |
+
|
| 158 |
+
# abort condition (handle complete graph)
|
| 159 |
+
if min_degree == len(graph_dict) - 1:
|
| 160 |
+
return None
|
| 161 |
+
|
| 162 |
+
for node in nodes_by_degree:
|
| 163 |
+
num_fill_in = 0
|
| 164 |
+
nbrs = graph_dict[node]
|
| 165 |
+
for nbr in nbrs:
|
| 166 |
+
# count how many nodes in nbrs current nbr is not connected to
|
| 167 |
+
# subtract 1 for the node itself
|
| 168 |
+
num_fill_in += len(nbrs - graph_dict[nbr]) - 1
|
| 169 |
+
if num_fill_in >= 2 * min_fill_in:
|
| 170 |
+
break
|
| 171 |
+
|
| 172 |
+
num_fill_in /= 2 # divide by 2 because of double counting
|
| 173 |
+
|
| 174 |
+
if num_fill_in < min_fill_in: # update min-fill-in node
|
| 175 |
+
if num_fill_in == 0:
|
| 176 |
+
return node
|
| 177 |
+
min_fill_in = num_fill_in
|
| 178 |
+
min_fill_in_node = node
|
| 179 |
+
|
| 180 |
+
return min_fill_in_node
|
| 181 |
+
|
| 182 |
+
|
| 183 |
+
@nx._dispatchable(returns_graph=True)
|
| 184 |
+
def treewidth_decomp(G, heuristic=min_fill_in_heuristic):
|
| 185 |
+
"""Returns a treewidth decomposition using the passed heuristic.
|
| 186 |
+
|
| 187 |
+
Parameters
|
| 188 |
+
----------
|
| 189 |
+
G : NetworkX graph
|
| 190 |
+
heuristic : heuristic function
|
| 191 |
+
|
| 192 |
+
Returns
|
| 193 |
+
-------
|
| 194 |
+
Treewidth decomposition : (int, Graph) tuple
|
| 195 |
+
2-tuple with treewidth and the corresponding decomposed tree.
|
| 196 |
+
"""
|
| 197 |
+
|
| 198 |
+
# make dict-of-sets structure
|
| 199 |
+
graph_dict = {n: set(G[n]) - {n} for n in G}
|
| 200 |
+
|
| 201 |
+
# stack containing nodes and neighbors in the order from the heuristic
|
| 202 |
+
node_stack = []
|
| 203 |
+
|
| 204 |
+
# get first node from heuristic
|
| 205 |
+
elim_node = heuristic(graph_dict)
|
| 206 |
+
while elim_node is not None:
|
| 207 |
+
# connect all neighbors with each other
|
| 208 |
+
nbrs = graph_dict[elim_node]
|
| 209 |
+
for u, v in itertools.permutations(nbrs, 2):
|
| 210 |
+
if v not in graph_dict[u]:
|
| 211 |
+
graph_dict[u].add(v)
|
| 212 |
+
|
| 213 |
+
# push node and its current neighbors on stack
|
| 214 |
+
node_stack.append((elim_node, nbrs))
|
| 215 |
+
|
| 216 |
+
# remove node from graph_dict
|
| 217 |
+
for u in graph_dict[elim_node]:
|
| 218 |
+
graph_dict[u].remove(elim_node)
|
| 219 |
+
|
| 220 |
+
del graph_dict[elim_node]
|
| 221 |
+
elim_node = heuristic(graph_dict)
|
| 222 |
+
|
| 223 |
+
# the abort condition is met; put all remaining nodes into one bag
|
| 224 |
+
decomp = nx.Graph()
|
| 225 |
+
first_bag = frozenset(graph_dict.keys())
|
| 226 |
+
decomp.add_node(first_bag)
|
| 227 |
+
|
| 228 |
+
treewidth = len(first_bag) - 1
|
| 229 |
+
|
| 230 |
+
while node_stack:
|
| 231 |
+
# get node and its neighbors from the stack
|
| 232 |
+
(curr_node, nbrs) = node_stack.pop()
|
| 233 |
+
|
| 234 |
+
# find a bag all neighbors are in
|
| 235 |
+
old_bag = None
|
| 236 |
+
for bag in decomp.nodes:
|
| 237 |
+
if nbrs <= bag:
|
| 238 |
+
old_bag = bag
|
| 239 |
+
break
|
| 240 |
+
|
| 241 |
+
if old_bag is None:
|
| 242 |
+
# no old_bag was found: just connect to the first_bag
|
| 243 |
+
old_bag = first_bag
|
| 244 |
+
|
| 245 |
+
# create new node for decomposition
|
| 246 |
+
nbrs.add(curr_node)
|
| 247 |
+
new_bag = frozenset(nbrs)
|
| 248 |
+
|
| 249 |
+
# update treewidth
|
| 250 |
+
treewidth = max(treewidth, len(new_bag) - 1)
|
| 251 |
+
|
| 252 |
+
# add edge to decomposition (implicitly also adds the new node)
|
| 253 |
+
decomp.add_edge(old_bag, new_bag)
|
| 254 |
+
|
| 255 |
+
return treewidth, decomp
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/approximation/vertex_cover.py
ADDED
|
@@ -0,0 +1,83 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for computing an approximate minimum weight vertex cover.
|
| 2 |
+
|
| 3 |
+
A |vertex cover|_ is a subset of nodes such that each edge in the graph
|
| 4 |
+
is incident to at least one node in the subset.
|
| 5 |
+
|
| 6 |
+
.. _vertex cover: https://en.wikipedia.org/wiki/Vertex_cover
|
| 7 |
+
.. |vertex cover| replace:: *vertex cover*
|
| 8 |
+
|
| 9 |
+
"""
|
| 10 |
+
|
| 11 |
+
import networkx as nx
|
| 12 |
+
|
| 13 |
+
__all__ = ["min_weighted_vertex_cover"]
|
| 14 |
+
|
| 15 |
+
|
| 16 |
+
@nx._dispatchable(node_attrs="weight")
|
| 17 |
+
def min_weighted_vertex_cover(G, weight=None):
|
| 18 |
+
r"""Returns an approximate minimum weighted vertex cover.
|
| 19 |
+
|
| 20 |
+
The set of nodes returned by this function is guaranteed to be a
|
| 21 |
+
vertex cover, and the total weight of the set is guaranteed to be at
|
| 22 |
+
most twice the total weight of the minimum weight vertex cover. In
|
| 23 |
+
other words,
|
| 24 |
+
|
| 25 |
+
.. math::
|
| 26 |
+
|
| 27 |
+
w(S) \leq 2 * w(S^*),
|
| 28 |
+
|
| 29 |
+
where $S$ is the vertex cover returned by this function,
|
| 30 |
+
$S^*$ is the vertex cover of minimum weight out of all vertex
|
| 31 |
+
covers of the graph, and $w$ is the function that computes the
|
| 32 |
+
sum of the weights of each node in that given set.
|
| 33 |
+
|
| 34 |
+
Parameters
|
| 35 |
+
----------
|
| 36 |
+
G : NetworkX graph
|
| 37 |
+
|
| 38 |
+
weight : string, optional (default = None)
|
| 39 |
+
If None, every node has weight 1. If a string, use this node
|
| 40 |
+
attribute as the node weight. A node without this attribute is
|
| 41 |
+
assumed to have weight 1.
|
| 42 |
+
|
| 43 |
+
Returns
|
| 44 |
+
-------
|
| 45 |
+
min_weighted_cover : set
|
| 46 |
+
Returns a set of nodes whose weight sum is no more than twice
|
| 47 |
+
the weight sum of the minimum weight vertex cover.
|
| 48 |
+
|
| 49 |
+
Notes
|
| 50 |
+
-----
|
| 51 |
+
For a directed graph, a vertex cover has the same definition: a set
|
| 52 |
+
of nodes such that each edge in the graph is incident to at least
|
| 53 |
+
one node in the set. Whether the node is the head or tail of the
|
| 54 |
+
directed edge is ignored.
|
| 55 |
+
|
| 56 |
+
This is the local-ratio algorithm for computing an approximate
|
| 57 |
+
vertex cover. The algorithm greedily reduces the costs over edges,
|
| 58 |
+
iteratively building a cover. The worst-case runtime of this
|
| 59 |
+
implementation is $O(m \log n)$, where $n$ is the number
|
| 60 |
+
of nodes and $m$ the number of edges in the graph.
|
| 61 |
+
|
| 62 |
+
References
|
| 63 |
+
----------
|
| 64 |
+
.. [1] Bar-Yehuda, R., and Even, S. (1985). "A local-ratio theorem for
|
| 65 |
+
approximating the weighted vertex cover problem."
|
| 66 |
+
*Annals of Discrete Mathematics*, 25, 27–46
|
| 67 |
+
<http://www.cs.technion.ac.il/~reuven/PDF/vc_lr.pdf>
|
| 68 |
+
|
| 69 |
+
"""
|
| 70 |
+
cost = dict(G.nodes(data=weight, default=1))
|
| 71 |
+
# While there are uncovered edges, choose an uncovered and update
|
| 72 |
+
# the cost of the remaining edges.
|
| 73 |
+
cover = set()
|
| 74 |
+
for u, v in G.edges():
|
| 75 |
+
if u in cover or v in cover:
|
| 76 |
+
continue
|
| 77 |
+
if cost[u] <= cost[v]:
|
| 78 |
+
cover.add(u)
|
| 79 |
+
cost[v] -= cost[u]
|
| 80 |
+
else:
|
| 81 |
+
cover.add(v)
|
| 82 |
+
cost[u] -= cost[v]
|
| 83 |
+
return cover
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/__init__.py
ADDED
|
@@ -0,0 +1,5 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
from networkx.algorithms.assortativity.connectivity import *
|
| 2 |
+
from networkx.algorithms.assortativity.correlation import *
|
| 3 |
+
from networkx.algorithms.assortativity.mixing import *
|
| 4 |
+
from networkx.algorithms.assortativity.neighbor_degree import *
|
| 5 |
+
from networkx.algorithms.assortativity.pairs import *
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/connectivity.py
ADDED
|
@@ -0,0 +1,122 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
from collections import defaultdict
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
|
| 5 |
+
__all__ = ["average_degree_connectivity"]
|
| 6 |
+
|
| 7 |
+
|
| 8 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 9 |
+
def average_degree_connectivity(
|
| 10 |
+
G, source="in+out", target="in+out", nodes=None, weight=None
|
| 11 |
+
):
|
| 12 |
+
r"""Compute the average degree connectivity of graph.
|
| 13 |
+
|
| 14 |
+
The average degree connectivity is the average nearest neighbor degree of
|
| 15 |
+
nodes with degree k. For weighted graphs, an analogous measure can
|
| 16 |
+
be computed using the weighted average neighbors degree defined in
|
| 17 |
+
[1]_, for a node `i`, as
|
| 18 |
+
|
| 19 |
+
.. math::
|
| 20 |
+
|
| 21 |
+
k_{nn,i}^{w} = \frac{1}{s_i} \sum_{j \in N(i)} w_{ij} k_j
|
| 22 |
+
|
| 23 |
+
where `s_i` is the weighted degree of node `i`,
|
| 24 |
+
`w_{ij}` is the weight of the edge that links `i` and `j`,
|
| 25 |
+
and `N(i)` are the neighbors of node `i`.
|
| 26 |
+
|
| 27 |
+
Parameters
|
| 28 |
+
----------
|
| 29 |
+
G : NetworkX graph
|
| 30 |
+
|
| 31 |
+
source : "in"|"out"|"in+out" (default:"in+out")
|
| 32 |
+
Directed graphs only. Use "in"- or "out"-degree for source node.
|
| 33 |
+
|
| 34 |
+
target : "in"|"out"|"in+out" (default:"in+out"
|
| 35 |
+
Directed graphs only. Use "in"- or "out"-degree for target node.
|
| 36 |
+
|
| 37 |
+
nodes : list or iterable (optional)
|
| 38 |
+
Compute neighbor connectivity for these nodes. The default is all
|
| 39 |
+
nodes.
|
| 40 |
+
|
| 41 |
+
weight : string or None, optional (default=None)
|
| 42 |
+
The edge attribute that holds the numerical value used as a weight.
|
| 43 |
+
If None, then each edge has weight 1.
|
| 44 |
+
|
| 45 |
+
Returns
|
| 46 |
+
-------
|
| 47 |
+
d : dict
|
| 48 |
+
A dictionary keyed by degree k with the value of average connectivity.
|
| 49 |
+
|
| 50 |
+
Raises
|
| 51 |
+
------
|
| 52 |
+
NetworkXError
|
| 53 |
+
If either `source` or `target` are not one of 'in',
|
| 54 |
+
'out', or 'in+out'.
|
| 55 |
+
If either `source` or `target` is passed for an undirected graph.
|
| 56 |
+
|
| 57 |
+
Examples
|
| 58 |
+
--------
|
| 59 |
+
>>> G = nx.path_graph(4)
|
| 60 |
+
>>> G.edges[1, 2]["weight"] = 3
|
| 61 |
+
>>> nx.average_degree_connectivity(G)
|
| 62 |
+
{1: 2.0, 2: 1.5}
|
| 63 |
+
>>> nx.average_degree_connectivity(G, weight="weight")
|
| 64 |
+
{1: 2.0, 2: 1.75}
|
| 65 |
+
|
| 66 |
+
See Also
|
| 67 |
+
--------
|
| 68 |
+
average_neighbor_degree
|
| 69 |
+
|
| 70 |
+
References
|
| 71 |
+
----------
|
| 72 |
+
.. [1] A. Barrat, M. Barthélemy, R. Pastor-Satorras, and A. Vespignani,
|
| 73 |
+
"The architecture of complex weighted networks".
|
| 74 |
+
PNAS 101 (11): 3747–3752 (2004).
|
| 75 |
+
"""
|
| 76 |
+
# First, determine the type of neighbors and the type of degree to use.
|
| 77 |
+
if G.is_directed():
|
| 78 |
+
if source not in ("in", "out", "in+out"):
|
| 79 |
+
raise nx.NetworkXError('source must be one of "in", "out", or "in+out"')
|
| 80 |
+
if target not in ("in", "out", "in+out"):
|
| 81 |
+
raise nx.NetworkXError('target must be one of "in", "out", or "in+out"')
|
| 82 |
+
direction = {"out": G.out_degree, "in": G.in_degree, "in+out": G.degree}
|
| 83 |
+
neighbor_funcs = {
|
| 84 |
+
"out": G.successors,
|
| 85 |
+
"in": G.predecessors,
|
| 86 |
+
"in+out": G.neighbors,
|
| 87 |
+
}
|
| 88 |
+
source_degree = direction[source]
|
| 89 |
+
target_degree = direction[target]
|
| 90 |
+
neighbors = neighbor_funcs[source]
|
| 91 |
+
# `reverse` indicates whether to look at the in-edge when
|
| 92 |
+
# computing the weight of an edge.
|
| 93 |
+
reverse = source == "in"
|
| 94 |
+
else:
|
| 95 |
+
if source != "in+out" or target != "in+out":
|
| 96 |
+
raise nx.NetworkXError(
|
| 97 |
+
f"source and target arguments are only supported for directed graphs"
|
| 98 |
+
)
|
| 99 |
+
source_degree = G.degree
|
| 100 |
+
target_degree = G.degree
|
| 101 |
+
neighbors = G.neighbors
|
| 102 |
+
reverse = False
|
| 103 |
+
dsum = defaultdict(int)
|
| 104 |
+
dnorm = defaultdict(int)
|
| 105 |
+
# Check if `source_nodes` is actually a single node in the graph.
|
| 106 |
+
source_nodes = source_degree(nodes)
|
| 107 |
+
if nodes in G:
|
| 108 |
+
source_nodes = [(nodes, source_degree(nodes))]
|
| 109 |
+
for n, k in source_nodes:
|
| 110 |
+
nbrdeg = target_degree(neighbors(n))
|
| 111 |
+
if weight is None:
|
| 112 |
+
s = sum(d for n, d in nbrdeg)
|
| 113 |
+
else: # weight nbr degree by weight of (n,nbr) edge
|
| 114 |
+
if reverse:
|
| 115 |
+
s = sum(G[nbr][n].get(weight, 1) * d for nbr, d in nbrdeg)
|
| 116 |
+
else:
|
| 117 |
+
s = sum(G[n][nbr].get(weight, 1) * d for nbr, d in nbrdeg)
|
| 118 |
+
dnorm[k] += source_degree(n, weight=weight)
|
| 119 |
+
dsum[k] += s
|
| 120 |
+
|
| 121 |
+
# normalize
|
| 122 |
+
return {k: avg if dnorm[k] == 0 else avg / dnorm[k] for k, avg in dsum.items()}
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/correlation.py
ADDED
|
@@ -0,0 +1,302 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Node assortativity coefficients and correlation measures."""
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
from networkx.algorithms.assortativity.mixing import (
|
| 5 |
+
attribute_mixing_matrix,
|
| 6 |
+
degree_mixing_matrix,
|
| 7 |
+
)
|
| 8 |
+
from networkx.algorithms.assortativity.pairs import node_degree_xy
|
| 9 |
+
|
| 10 |
+
__all__ = [
|
| 11 |
+
"degree_pearson_correlation_coefficient",
|
| 12 |
+
"degree_assortativity_coefficient",
|
| 13 |
+
"attribute_assortativity_coefficient",
|
| 14 |
+
"numeric_assortativity_coefficient",
|
| 15 |
+
]
|
| 16 |
+
|
| 17 |
+
|
| 18 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 19 |
+
def degree_assortativity_coefficient(G, x="out", y="in", weight=None, nodes=None):
|
| 20 |
+
"""Compute degree assortativity of graph.
|
| 21 |
+
|
| 22 |
+
Assortativity measures the similarity of connections
|
| 23 |
+
in the graph with respect to the node degree.
|
| 24 |
+
|
| 25 |
+
Parameters
|
| 26 |
+
----------
|
| 27 |
+
G : NetworkX graph
|
| 28 |
+
|
| 29 |
+
x: string ('in','out')
|
| 30 |
+
The degree type for source node (directed graphs only).
|
| 31 |
+
|
| 32 |
+
y: string ('in','out')
|
| 33 |
+
The degree type for target node (directed graphs only).
|
| 34 |
+
|
| 35 |
+
weight: string or None, optional (default=None)
|
| 36 |
+
The edge attribute that holds the numerical value used
|
| 37 |
+
as a weight. If None, then each edge has weight 1.
|
| 38 |
+
The degree is the sum of the edge weights adjacent to the node.
|
| 39 |
+
|
| 40 |
+
nodes: list or iterable (optional)
|
| 41 |
+
Compute degree assortativity only for nodes in container.
|
| 42 |
+
The default is all nodes.
|
| 43 |
+
|
| 44 |
+
Returns
|
| 45 |
+
-------
|
| 46 |
+
r : float
|
| 47 |
+
Assortativity of graph by degree.
|
| 48 |
+
|
| 49 |
+
Examples
|
| 50 |
+
--------
|
| 51 |
+
>>> G = nx.path_graph(4)
|
| 52 |
+
>>> r = nx.degree_assortativity_coefficient(G)
|
| 53 |
+
>>> print(f"{r:3.1f}")
|
| 54 |
+
-0.5
|
| 55 |
+
|
| 56 |
+
See Also
|
| 57 |
+
--------
|
| 58 |
+
attribute_assortativity_coefficient
|
| 59 |
+
numeric_assortativity_coefficient
|
| 60 |
+
degree_mixing_dict
|
| 61 |
+
degree_mixing_matrix
|
| 62 |
+
|
| 63 |
+
Notes
|
| 64 |
+
-----
|
| 65 |
+
This computes Eq. (21) in Ref. [1]_ , where e is the joint
|
| 66 |
+
probability distribution (mixing matrix) of the degrees. If G is
|
| 67 |
+
directed than the matrix e is the joint probability of the
|
| 68 |
+
user-specified degree type for the source and target.
|
| 69 |
+
|
| 70 |
+
References
|
| 71 |
+
----------
|
| 72 |
+
.. [1] M. E. J. Newman, Mixing patterns in networks,
|
| 73 |
+
Physical Review E, 67 026126, 2003
|
| 74 |
+
.. [2] Foster, J.G., Foster, D.V., Grassberger, P. & Paczuski, M.
|
| 75 |
+
Edge direction and the structure of networks, PNAS 107, 10815-20 (2010).
|
| 76 |
+
"""
|
| 77 |
+
if nodes is None:
|
| 78 |
+
nodes = G.nodes
|
| 79 |
+
|
| 80 |
+
degrees = None
|
| 81 |
+
|
| 82 |
+
if G.is_directed():
|
| 83 |
+
indeg = (
|
| 84 |
+
{d for _, d in G.in_degree(nodes, weight=weight)}
|
| 85 |
+
if "in" in (x, y)
|
| 86 |
+
else set()
|
| 87 |
+
)
|
| 88 |
+
outdeg = (
|
| 89 |
+
{d for _, d in G.out_degree(nodes, weight=weight)}
|
| 90 |
+
if "out" in (x, y)
|
| 91 |
+
else set()
|
| 92 |
+
)
|
| 93 |
+
degrees = set.union(indeg, outdeg)
|
| 94 |
+
else:
|
| 95 |
+
degrees = {d for _, d in G.degree(nodes, weight=weight)}
|
| 96 |
+
|
| 97 |
+
mapping = {d: i for i, d in enumerate(degrees)}
|
| 98 |
+
M = degree_mixing_matrix(G, x=x, y=y, nodes=nodes, weight=weight, mapping=mapping)
|
| 99 |
+
|
| 100 |
+
return _numeric_ac(M, mapping=mapping)
|
| 101 |
+
|
| 102 |
+
|
| 103 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 104 |
+
def degree_pearson_correlation_coefficient(G, x="out", y="in", weight=None, nodes=None):
|
| 105 |
+
"""Compute degree assortativity of graph.
|
| 106 |
+
|
| 107 |
+
Assortativity measures the similarity of connections
|
| 108 |
+
in the graph with respect to the node degree.
|
| 109 |
+
|
| 110 |
+
This is the same as degree_assortativity_coefficient but uses the
|
| 111 |
+
potentially faster scipy.stats.pearsonr function.
|
| 112 |
+
|
| 113 |
+
Parameters
|
| 114 |
+
----------
|
| 115 |
+
G : NetworkX graph
|
| 116 |
+
|
| 117 |
+
x: string ('in','out')
|
| 118 |
+
The degree type for source node (directed graphs only).
|
| 119 |
+
|
| 120 |
+
y: string ('in','out')
|
| 121 |
+
The degree type for target node (directed graphs only).
|
| 122 |
+
|
| 123 |
+
weight: string or None, optional (default=None)
|
| 124 |
+
The edge attribute that holds the numerical value used
|
| 125 |
+
as a weight. If None, then each edge has weight 1.
|
| 126 |
+
The degree is the sum of the edge weights adjacent to the node.
|
| 127 |
+
|
| 128 |
+
nodes: list or iterable (optional)
|
| 129 |
+
Compute pearson correlation of degrees only for specified nodes.
|
| 130 |
+
The default is all nodes.
|
| 131 |
+
|
| 132 |
+
Returns
|
| 133 |
+
-------
|
| 134 |
+
r : float
|
| 135 |
+
Assortativity of graph by degree.
|
| 136 |
+
|
| 137 |
+
Examples
|
| 138 |
+
--------
|
| 139 |
+
>>> G = nx.path_graph(4)
|
| 140 |
+
>>> r = nx.degree_pearson_correlation_coefficient(G)
|
| 141 |
+
>>> print(f"{r:3.1f}")
|
| 142 |
+
-0.5
|
| 143 |
+
|
| 144 |
+
Notes
|
| 145 |
+
-----
|
| 146 |
+
This calls scipy.stats.pearsonr.
|
| 147 |
+
|
| 148 |
+
References
|
| 149 |
+
----------
|
| 150 |
+
.. [1] M. E. J. Newman, Mixing patterns in networks
|
| 151 |
+
Physical Review E, 67 026126, 2003
|
| 152 |
+
.. [2] Foster, J.G., Foster, D.V., Grassberger, P. & Paczuski, M.
|
| 153 |
+
Edge direction and the structure of networks, PNAS 107, 10815-20 (2010).
|
| 154 |
+
"""
|
| 155 |
+
import scipy as sp
|
| 156 |
+
|
| 157 |
+
xy = node_degree_xy(G, x=x, y=y, nodes=nodes, weight=weight)
|
| 158 |
+
x, y = zip(*xy)
|
| 159 |
+
return float(sp.stats.pearsonr(x, y)[0])
|
| 160 |
+
|
| 161 |
+
|
| 162 |
+
@nx._dispatchable(node_attrs="attribute")
|
| 163 |
+
def attribute_assortativity_coefficient(G, attribute, nodes=None):
|
| 164 |
+
"""Compute assortativity for node attributes.
|
| 165 |
+
|
| 166 |
+
Assortativity measures the similarity of connections
|
| 167 |
+
in the graph with respect to the given attribute.
|
| 168 |
+
|
| 169 |
+
Parameters
|
| 170 |
+
----------
|
| 171 |
+
G : NetworkX graph
|
| 172 |
+
|
| 173 |
+
attribute : string
|
| 174 |
+
Node attribute key
|
| 175 |
+
|
| 176 |
+
nodes: list or iterable (optional)
|
| 177 |
+
Compute attribute assortativity for nodes in container.
|
| 178 |
+
The default is all nodes.
|
| 179 |
+
|
| 180 |
+
Returns
|
| 181 |
+
-------
|
| 182 |
+
r: float
|
| 183 |
+
Assortativity of graph for given attribute
|
| 184 |
+
|
| 185 |
+
Examples
|
| 186 |
+
--------
|
| 187 |
+
>>> G = nx.Graph()
|
| 188 |
+
>>> G.add_nodes_from([0, 1], color="red")
|
| 189 |
+
>>> G.add_nodes_from([2, 3], color="blue")
|
| 190 |
+
>>> G.add_edges_from([(0, 1), (2, 3)])
|
| 191 |
+
>>> print(nx.attribute_assortativity_coefficient(G, "color"))
|
| 192 |
+
1.0
|
| 193 |
+
|
| 194 |
+
Notes
|
| 195 |
+
-----
|
| 196 |
+
This computes Eq. (2) in Ref. [1]_ , (trace(M)-sum(M^2))/(1-sum(M^2)),
|
| 197 |
+
where M is the joint probability distribution (mixing matrix)
|
| 198 |
+
of the specified attribute.
|
| 199 |
+
|
| 200 |
+
References
|
| 201 |
+
----------
|
| 202 |
+
.. [1] M. E. J. Newman, Mixing patterns in networks,
|
| 203 |
+
Physical Review E, 67 026126, 2003
|
| 204 |
+
"""
|
| 205 |
+
M = attribute_mixing_matrix(G, attribute, nodes)
|
| 206 |
+
return attribute_ac(M)
|
| 207 |
+
|
| 208 |
+
|
| 209 |
+
@nx._dispatchable(node_attrs="attribute")
|
| 210 |
+
def numeric_assortativity_coefficient(G, attribute, nodes=None):
|
| 211 |
+
"""Compute assortativity for numerical node attributes.
|
| 212 |
+
|
| 213 |
+
Assortativity measures the similarity of connections
|
| 214 |
+
in the graph with respect to the given numeric attribute.
|
| 215 |
+
|
| 216 |
+
Parameters
|
| 217 |
+
----------
|
| 218 |
+
G : NetworkX graph
|
| 219 |
+
|
| 220 |
+
attribute : string
|
| 221 |
+
Node attribute key.
|
| 222 |
+
|
| 223 |
+
nodes: list or iterable (optional)
|
| 224 |
+
Compute numeric assortativity only for attributes of nodes in
|
| 225 |
+
container. The default is all nodes.
|
| 226 |
+
|
| 227 |
+
Returns
|
| 228 |
+
-------
|
| 229 |
+
r: float
|
| 230 |
+
Assortativity of graph for given attribute
|
| 231 |
+
|
| 232 |
+
Examples
|
| 233 |
+
--------
|
| 234 |
+
>>> G = nx.Graph()
|
| 235 |
+
>>> G.add_nodes_from([0, 1], size=2)
|
| 236 |
+
>>> G.add_nodes_from([2, 3], size=3)
|
| 237 |
+
>>> G.add_edges_from([(0, 1), (2, 3)])
|
| 238 |
+
>>> print(nx.numeric_assortativity_coefficient(G, "size"))
|
| 239 |
+
1.0
|
| 240 |
+
|
| 241 |
+
Notes
|
| 242 |
+
-----
|
| 243 |
+
This computes Eq. (21) in Ref. [1]_ , which is the Pearson correlation
|
| 244 |
+
coefficient of the specified (scalar valued) attribute across edges.
|
| 245 |
+
|
| 246 |
+
References
|
| 247 |
+
----------
|
| 248 |
+
.. [1] M. E. J. Newman, Mixing patterns in networks
|
| 249 |
+
Physical Review E, 67 026126, 2003
|
| 250 |
+
"""
|
| 251 |
+
if nodes is None:
|
| 252 |
+
nodes = G.nodes
|
| 253 |
+
vals = {G.nodes[n][attribute] for n in nodes}
|
| 254 |
+
mapping = {d: i for i, d in enumerate(vals)}
|
| 255 |
+
M = attribute_mixing_matrix(G, attribute, nodes, mapping)
|
| 256 |
+
return _numeric_ac(M, mapping)
|
| 257 |
+
|
| 258 |
+
|
| 259 |
+
def attribute_ac(M):
|
| 260 |
+
"""Compute assortativity for attribute matrix M.
|
| 261 |
+
|
| 262 |
+
Parameters
|
| 263 |
+
----------
|
| 264 |
+
M : numpy.ndarray
|
| 265 |
+
2D ndarray representing the attribute mixing matrix.
|
| 266 |
+
|
| 267 |
+
Notes
|
| 268 |
+
-----
|
| 269 |
+
This computes Eq. (2) in Ref. [1]_ , (trace(e)-sum(e^2))/(1-sum(e^2)),
|
| 270 |
+
where e is the joint probability distribution (mixing matrix)
|
| 271 |
+
of the specified attribute.
|
| 272 |
+
|
| 273 |
+
References
|
| 274 |
+
----------
|
| 275 |
+
.. [1] M. E. J. Newman, Mixing patterns in networks,
|
| 276 |
+
Physical Review E, 67 026126, 2003
|
| 277 |
+
"""
|
| 278 |
+
if M.sum() != 1.0:
|
| 279 |
+
M = M / M.sum()
|
| 280 |
+
s = (M @ M).sum()
|
| 281 |
+
t = M.trace()
|
| 282 |
+
r = (t - s) / (1 - s)
|
| 283 |
+
return float(r)
|
| 284 |
+
|
| 285 |
+
|
| 286 |
+
def _numeric_ac(M, mapping):
|
| 287 |
+
# M is a 2D numpy array
|
| 288 |
+
# numeric assortativity coefficient, pearsonr
|
| 289 |
+
import numpy as np
|
| 290 |
+
|
| 291 |
+
if M.sum() != 1.0:
|
| 292 |
+
M = M / M.sum()
|
| 293 |
+
x = np.array(list(mapping.keys()))
|
| 294 |
+
y = x # x and y have the same support
|
| 295 |
+
idx = list(mapping.values())
|
| 296 |
+
a = M.sum(axis=0)
|
| 297 |
+
b = M.sum(axis=1)
|
| 298 |
+
vara = (a[idx] * x**2).sum() - ((a[idx] * x).sum()) ** 2
|
| 299 |
+
varb = (b[idx] * y**2).sum() - ((b[idx] * y).sum()) ** 2
|
| 300 |
+
xy = np.outer(x, y)
|
| 301 |
+
ab = np.outer(a[idx], b[idx])
|
| 302 |
+
return float((xy * (M - ab)).sum() / np.sqrt(vara * varb))
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/mixing.py
ADDED
|
@@ -0,0 +1,255 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
Mixing matrices for node attributes and degree.
|
| 3 |
+
"""
|
| 4 |
+
|
| 5 |
+
import networkx as nx
|
| 6 |
+
from networkx.algorithms.assortativity.pairs import node_attribute_xy, node_degree_xy
|
| 7 |
+
from networkx.utils import dict_to_numpy_array
|
| 8 |
+
|
| 9 |
+
__all__ = [
|
| 10 |
+
"attribute_mixing_matrix",
|
| 11 |
+
"attribute_mixing_dict",
|
| 12 |
+
"degree_mixing_matrix",
|
| 13 |
+
"degree_mixing_dict",
|
| 14 |
+
"mixing_dict",
|
| 15 |
+
]
|
| 16 |
+
|
| 17 |
+
|
| 18 |
+
@nx._dispatchable(node_attrs="attribute")
|
| 19 |
+
def attribute_mixing_dict(G, attribute, nodes=None, normalized=False):
|
| 20 |
+
"""Returns dictionary representation of mixing matrix for attribute.
|
| 21 |
+
|
| 22 |
+
Parameters
|
| 23 |
+
----------
|
| 24 |
+
G : graph
|
| 25 |
+
NetworkX graph object.
|
| 26 |
+
|
| 27 |
+
attribute : string
|
| 28 |
+
Node attribute key.
|
| 29 |
+
|
| 30 |
+
nodes: list or iterable (optional)
|
| 31 |
+
Unse nodes in container to build the dict. The default is all nodes.
|
| 32 |
+
|
| 33 |
+
normalized : bool (default=False)
|
| 34 |
+
Return counts if False or probabilities if True.
|
| 35 |
+
|
| 36 |
+
Examples
|
| 37 |
+
--------
|
| 38 |
+
>>> G = nx.Graph()
|
| 39 |
+
>>> G.add_nodes_from([0, 1], color="red")
|
| 40 |
+
>>> G.add_nodes_from([2, 3], color="blue")
|
| 41 |
+
>>> G.add_edge(1, 3)
|
| 42 |
+
>>> d = nx.attribute_mixing_dict(G, "color")
|
| 43 |
+
>>> print(d["red"]["blue"])
|
| 44 |
+
1
|
| 45 |
+
>>> print(d["blue"]["red"]) # d symmetric for undirected graphs
|
| 46 |
+
1
|
| 47 |
+
|
| 48 |
+
Returns
|
| 49 |
+
-------
|
| 50 |
+
d : dictionary
|
| 51 |
+
Counts or joint probability of occurrence of attribute pairs.
|
| 52 |
+
"""
|
| 53 |
+
xy_iter = node_attribute_xy(G, attribute, nodes)
|
| 54 |
+
return mixing_dict(xy_iter, normalized=normalized)
|
| 55 |
+
|
| 56 |
+
|
| 57 |
+
@nx._dispatchable(node_attrs="attribute")
|
| 58 |
+
def attribute_mixing_matrix(G, attribute, nodes=None, mapping=None, normalized=True):
|
| 59 |
+
"""Returns mixing matrix for attribute.
|
| 60 |
+
|
| 61 |
+
Parameters
|
| 62 |
+
----------
|
| 63 |
+
G : graph
|
| 64 |
+
NetworkX graph object.
|
| 65 |
+
|
| 66 |
+
attribute : string
|
| 67 |
+
Node attribute key.
|
| 68 |
+
|
| 69 |
+
nodes: list or iterable (optional)
|
| 70 |
+
Use only nodes in container to build the matrix. The default is
|
| 71 |
+
all nodes.
|
| 72 |
+
|
| 73 |
+
mapping : dictionary, optional
|
| 74 |
+
Mapping from node attribute to integer index in matrix.
|
| 75 |
+
If not specified, an arbitrary ordering will be used.
|
| 76 |
+
|
| 77 |
+
normalized : bool (default=True)
|
| 78 |
+
Return counts if False or probabilities if True.
|
| 79 |
+
|
| 80 |
+
Returns
|
| 81 |
+
-------
|
| 82 |
+
m: numpy array
|
| 83 |
+
Counts or joint probability of occurrence of attribute pairs.
|
| 84 |
+
|
| 85 |
+
Notes
|
| 86 |
+
-----
|
| 87 |
+
If each node has a unique attribute value, the unnormalized mixing matrix
|
| 88 |
+
will be equal to the adjacency matrix. To get a denser mixing matrix,
|
| 89 |
+
the rounding can be performed to form groups of nodes with equal values.
|
| 90 |
+
For example, the exact height of persons in cm (180.79155222, 163.9080892,
|
| 91 |
+
163.30095355, 167.99016217, 168.21590163, ...) can be rounded to (180, 163,
|
| 92 |
+
163, 168, 168, ...).
|
| 93 |
+
|
| 94 |
+
Definitions of attribute mixing matrix vary on whether the matrix
|
| 95 |
+
should include rows for attribute values that don't arise. Here we
|
| 96 |
+
do not include such empty-rows. But you can force them to appear
|
| 97 |
+
by inputting a `mapping` that includes those values.
|
| 98 |
+
|
| 99 |
+
Examples
|
| 100 |
+
--------
|
| 101 |
+
>>> G = nx.path_graph(3)
|
| 102 |
+
>>> gender = {0: "male", 1: "female", 2: "female"}
|
| 103 |
+
>>> nx.set_node_attributes(G, gender, "gender")
|
| 104 |
+
>>> mapping = {"male": 0, "female": 1}
|
| 105 |
+
>>> mix_mat = nx.attribute_mixing_matrix(G, "gender", mapping=mapping)
|
| 106 |
+
>>> mix_mat
|
| 107 |
+
array([[0. , 0.25],
|
| 108 |
+
[0.25, 0.5 ]])
|
| 109 |
+
"""
|
| 110 |
+
d = attribute_mixing_dict(G, attribute, nodes)
|
| 111 |
+
a = dict_to_numpy_array(d, mapping=mapping)
|
| 112 |
+
if normalized:
|
| 113 |
+
a = a / a.sum()
|
| 114 |
+
return a
|
| 115 |
+
|
| 116 |
+
|
| 117 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 118 |
+
def degree_mixing_dict(G, x="out", y="in", weight=None, nodes=None, normalized=False):
|
| 119 |
+
"""Returns dictionary representation of mixing matrix for degree.
|
| 120 |
+
|
| 121 |
+
Parameters
|
| 122 |
+
----------
|
| 123 |
+
G : graph
|
| 124 |
+
NetworkX graph object.
|
| 125 |
+
|
| 126 |
+
x: string ('in','out')
|
| 127 |
+
The degree type for source node (directed graphs only).
|
| 128 |
+
|
| 129 |
+
y: string ('in','out')
|
| 130 |
+
The degree type for target node (directed graphs only).
|
| 131 |
+
|
| 132 |
+
weight: string or None, optional (default=None)
|
| 133 |
+
The edge attribute that holds the numerical value used
|
| 134 |
+
as a weight. If None, then each edge has weight 1.
|
| 135 |
+
The degree is the sum of the edge weights adjacent to the node.
|
| 136 |
+
|
| 137 |
+
normalized : bool (default=False)
|
| 138 |
+
Return counts if False or probabilities if True.
|
| 139 |
+
|
| 140 |
+
Returns
|
| 141 |
+
-------
|
| 142 |
+
d: dictionary
|
| 143 |
+
Counts or joint probability of occurrence of degree pairs.
|
| 144 |
+
"""
|
| 145 |
+
xy_iter = node_degree_xy(G, x=x, y=y, nodes=nodes, weight=weight)
|
| 146 |
+
return mixing_dict(xy_iter, normalized=normalized)
|
| 147 |
+
|
| 148 |
+
|
| 149 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 150 |
+
def degree_mixing_matrix(
|
| 151 |
+
G, x="out", y="in", weight=None, nodes=None, normalized=True, mapping=None
|
| 152 |
+
):
|
| 153 |
+
"""Returns mixing matrix for attribute.
|
| 154 |
+
|
| 155 |
+
Parameters
|
| 156 |
+
----------
|
| 157 |
+
G : graph
|
| 158 |
+
NetworkX graph object.
|
| 159 |
+
|
| 160 |
+
x: string ('in','out')
|
| 161 |
+
The degree type for source node (directed graphs only).
|
| 162 |
+
|
| 163 |
+
y: string ('in','out')
|
| 164 |
+
The degree type for target node (directed graphs only).
|
| 165 |
+
|
| 166 |
+
nodes: list or iterable (optional)
|
| 167 |
+
Build the matrix using only nodes in container.
|
| 168 |
+
The default is all nodes.
|
| 169 |
+
|
| 170 |
+
weight: string or None, optional (default=None)
|
| 171 |
+
The edge attribute that holds the numerical value used
|
| 172 |
+
as a weight. If None, then each edge has weight 1.
|
| 173 |
+
The degree is the sum of the edge weights adjacent to the node.
|
| 174 |
+
|
| 175 |
+
normalized : bool (default=True)
|
| 176 |
+
Return counts if False or probabilities if True.
|
| 177 |
+
|
| 178 |
+
mapping : dictionary, optional
|
| 179 |
+
Mapping from node degree to integer index in matrix.
|
| 180 |
+
If not specified, an arbitrary ordering will be used.
|
| 181 |
+
|
| 182 |
+
Returns
|
| 183 |
+
-------
|
| 184 |
+
m: numpy array
|
| 185 |
+
Counts, or joint probability, of occurrence of node degree.
|
| 186 |
+
|
| 187 |
+
Notes
|
| 188 |
+
-----
|
| 189 |
+
Definitions of degree mixing matrix vary on whether the matrix
|
| 190 |
+
should include rows for degree values that don't arise. Here we
|
| 191 |
+
do not include such empty-rows. But you can force them to appear
|
| 192 |
+
by inputting a `mapping` that includes those values. See examples.
|
| 193 |
+
|
| 194 |
+
Examples
|
| 195 |
+
--------
|
| 196 |
+
>>> G = nx.star_graph(3)
|
| 197 |
+
>>> mix_mat = nx.degree_mixing_matrix(G)
|
| 198 |
+
>>> mix_mat
|
| 199 |
+
array([[0. , 0.5],
|
| 200 |
+
[0.5, 0. ]])
|
| 201 |
+
|
| 202 |
+
If you want every possible degree to appear as a row, even if no nodes
|
| 203 |
+
have that degree, use `mapping` as follows,
|
| 204 |
+
|
| 205 |
+
>>> max_degree = max(deg for n, deg in G.degree)
|
| 206 |
+
>>> mapping = {x: x for x in range(max_degree + 1)} # identity mapping
|
| 207 |
+
>>> mix_mat = nx.degree_mixing_matrix(G, mapping=mapping)
|
| 208 |
+
>>> mix_mat
|
| 209 |
+
array([[0. , 0. , 0. , 0. ],
|
| 210 |
+
[0. , 0. , 0. , 0.5],
|
| 211 |
+
[0. , 0. , 0. , 0. ],
|
| 212 |
+
[0. , 0.5, 0. , 0. ]])
|
| 213 |
+
"""
|
| 214 |
+
d = degree_mixing_dict(G, x=x, y=y, nodes=nodes, weight=weight)
|
| 215 |
+
a = dict_to_numpy_array(d, mapping=mapping)
|
| 216 |
+
if normalized:
|
| 217 |
+
a = a / a.sum()
|
| 218 |
+
return a
|
| 219 |
+
|
| 220 |
+
|
| 221 |
+
def mixing_dict(xy, normalized=False):
|
| 222 |
+
"""Returns a dictionary representation of mixing matrix.
|
| 223 |
+
|
| 224 |
+
Parameters
|
| 225 |
+
----------
|
| 226 |
+
xy : list or container of two-tuples
|
| 227 |
+
Pairs of (x,y) items.
|
| 228 |
+
|
| 229 |
+
attribute : string
|
| 230 |
+
Node attribute key
|
| 231 |
+
|
| 232 |
+
normalized : bool (default=False)
|
| 233 |
+
Return counts if False or probabilities if True.
|
| 234 |
+
|
| 235 |
+
Returns
|
| 236 |
+
-------
|
| 237 |
+
d: dictionary
|
| 238 |
+
Counts or Joint probability of occurrence of values in xy.
|
| 239 |
+
"""
|
| 240 |
+
d = {}
|
| 241 |
+
psum = 0.0
|
| 242 |
+
for x, y in xy:
|
| 243 |
+
if x not in d:
|
| 244 |
+
d[x] = {}
|
| 245 |
+
if y not in d:
|
| 246 |
+
d[y] = {}
|
| 247 |
+
v = d[x].get(y, 0)
|
| 248 |
+
d[x][y] = v + 1
|
| 249 |
+
psum += 1
|
| 250 |
+
|
| 251 |
+
if normalized:
|
| 252 |
+
for _, jdict in d.items():
|
| 253 |
+
for j in jdict:
|
| 254 |
+
jdict[j] /= psum
|
| 255 |
+
return d
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/neighbor_degree.py
ADDED
|
@@ -0,0 +1,160 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
import networkx as nx
|
| 2 |
+
|
| 3 |
+
__all__ = ["average_neighbor_degree"]
|
| 4 |
+
|
| 5 |
+
|
| 6 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 7 |
+
def average_neighbor_degree(G, source="out", target="out", nodes=None, weight=None):
|
| 8 |
+
r"""Returns the average degree of the neighborhood of each node.
|
| 9 |
+
|
| 10 |
+
In an undirected graph, the neighborhood `N(i)` of node `i` contains the
|
| 11 |
+
nodes that are connected to `i` by an edge.
|
| 12 |
+
|
| 13 |
+
For directed graphs, `N(i)` is defined according to the parameter `source`:
|
| 14 |
+
|
| 15 |
+
- if source is 'in', then `N(i)` consists of predecessors of node `i`.
|
| 16 |
+
- if source is 'out', then `N(i)` consists of successors of node `i`.
|
| 17 |
+
- if source is 'in+out', then `N(i)` is both predecessors and successors.
|
| 18 |
+
|
| 19 |
+
The average neighborhood degree of a node `i` is
|
| 20 |
+
|
| 21 |
+
.. math::
|
| 22 |
+
|
| 23 |
+
k_{nn,i} = \frac{1}{|N(i)|} \sum_{j \in N(i)} k_j
|
| 24 |
+
|
| 25 |
+
where `N(i)` are the neighbors of node `i` and `k_j` is
|
| 26 |
+
the degree of node `j` which belongs to `N(i)`. For weighted
|
| 27 |
+
graphs, an analogous measure can be defined [1]_,
|
| 28 |
+
|
| 29 |
+
.. math::
|
| 30 |
+
|
| 31 |
+
k_{nn,i}^{w} = \frac{1}{s_i} \sum_{j \in N(i)} w_{ij} k_j
|
| 32 |
+
|
| 33 |
+
where `s_i` is the weighted degree of node `i`, `w_{ij}`
|
| 34 |
+
is the weight of the edge that links `i` and `j` and
|
| 35 |
+
`N(i)` are the neighbors of node `i`.
|
| 36 |
+
|
| 37 |
+
|
| 38 |
+
Parameters
|
| 39 |
+
----------
|
| 40 |
+
G : NetworkX graph
|
| 41 |
+
|
| 42 |
+
source : string ("in"|"out"|"in+out"), optional (default="out")
|
| 43 |
+
Directed graphs only.
|
| 44 |
+
Use "in"- or "out"-neighbors of source node.
|
| 45 |
+
|
| 46 |
+
target : string ("in"|"out"|"in+out"), optional (default="out")
|
| 47 |
+
Directed graphs only.
|
| 48 |
+
Use "in"- or "out"-degree for target node.
|
| 49 |
+
|
| 50 |
+
nodes : list or iterable, optional (default=G.nodes)
|
| 51 |
+
Compute neighbor degree only for specified nodes.
|
| 52 |
+
|
| 53 |
+
weight : string or None, optional (default=None)
|
| 54 |
+
The edge attribute that holds the numerical value used as a weight.
|
| 55 |
+
If None, then each edge has weight 1.
|
| 56 |
+
|
| 57 |
+
Returns
|
| 58 |
+
-------
|
| 59 |
+
d: dict
|
| 60 |
+
A dictionary keyed by node to the average degree of its neighbors.
|
| 61 |
+
|
| 62 |
+
Raises
|
| 63 |
+
------
|
| 64 |
+
NetworkXError
|
| 65 |
+
If either `source` or `target` are not one of 'in', 'out', or 'in+out'.
|
| 66 |
+
If either `source` or `target` is passed for an undirected graph.
|
| 67 |
+
|
| 68 |
+
Examples
|
| 69 |
+
--------
|
| 70 |
+
>>> G = nx.path_graph(4)
|
| 71 |
+
>>> G.edges[0, 1]["weight"] = 5
|
| 72 |
+
>>> G.edges[2, 3]["weight"] = 3
|
| 73 |
+
|
| 74 |
+
>>> nx.average_neighbor_degree(G)
|
| 75 |
+
{0: 2.0, 1: 1.5, 2: 1.5, 3: 2.0}
|
| 76 |
+
>>> nx.average_neighbor_degree(G, weight="weight")
|
| 77 |
+
{0: 2.0, 1: 1.1666666666666667, 2: 1.25, 3: 2.0}
|
| 78 |
+
|
| 79 |
+
>>> G = nx.DiGraph()
|
| 80 |
+
>>> nx.add_path(G, [0, 1, 2, 3])
|
| 81 |
+
>>> nx.average_neighbor_degree(G, source="in", target="in")
|
| 82 |
+
{0: 0.0, 1: 0.0, 2: 1.0, 3: 1.0}
|
| 83 |
+
|
| 84 |
+
>>> nx.average_neighbor_degree(G, source="out", target="out")
|
| 85 |
+
{0: 1.0, 1: 1.0, 2: 0.0, 3: 0.0}
|
| 86 |
+
|
| 87 |
+
See Also
|
| 88 |
+
--------
|
| 89 |
+
average_degree_connectivity
|
| 90 |
+
|
| 91 |
+
References
|
| 92 |
+
----------
|
| 93 |
+
.. [1] A. Barrat, M. Barthélemy, R. Pastor-Satorras, and A. Vespignani,
|
| 94 |
+
"The architecture of complex weighted networks".
|
| 95 |
+
PNAS 101 (11): 3747–3752 (2004).
|
| 96 |
+
"""
|
| 97 |
+
if G.is_directed():
|
| 98 |
+
if source == "in":
|
| 99 |
+
source_degree = G.in_degree
|
| 100 |
+
elif source == "out":
|
| 101 |
+
source_degree = G.out_degree
|
| 102 |
+
elif source == "in+out":
|
| 103 |
+
source_degree = G.degree
|
| 104 |
+
else:
|
| 105 |
+
raise nx.NetworkXError(
|
| 106 |
+
f"source argument {source} must be 'in', 'out' or 'in+out'"
|
| 107 |
+
)
|
| 108 |
+
|
| 109 |
+
if target == "in":
|
| 110 |
+
target_degree = G.in_degree
|
| 111 |
+
elif target == "out":
|
| 112 |
+
target_degree = G.out_degree
|
| 113 |
+
elif target == "in+out":
|
| 114 |
+
target_degree = G.degree
|
| 115 |
+
else:
|
| 116 |
+
raise nx.NetworkXError(
|
| 117 |
+
f"target argument {target} must be 'in', 'out' or 'in+out'"
|
| 118 |
+
)
|
| 119 |
+
else:
|
| 120 |
+
if source != "out" or target != "out":
|
| 121 |
+
raise nx.NetworkXError(
|
| 122 |
+
f"source and target arguments are only supported for directed graphs"
|
| 123 |
+
)
|
| 124 |
+
source_degree = target_degree = G.degree
|
| 125 |
+
|
| 126 |
+
# precompute target degrees -- should *not* be weighted degree
|
| 127 |
+
t_deg = dict(target_degree())
|
| 128 |
+
|
| 129 |
+
# Set up both predecessor and successor neighbor dicts leaving empty if not needed
|
| 130 |
+
G_P = G_S = {n: {} for n in G}
|
| 131 |
+
if G.is_directed():
|
| 132 |
+
# "in" or "in+out" cases: G_P contains predecessors
|
| 133 |
+
if "in" in source:
|
| 134 |
+
G_P = G.pred
|
| 135 |
+
# "out" or "in+out" cases: G_S contains successors
|
| 136 |
+
if "out" in source:
|
| 137 |
+
G_S = G.succ
|
| 138 |
+
else:
|
| 139 |
+
# undirected leave G_P empty but G_S is the adjacency
|
| 140 |
+
G_S = G.adj
|
| 141 |
+
|
| 142 |
+
# Main loop: Compute average degree of neighbors
|
| 143 |
+
avg = {}
|
| 144 |
+
for n, deg in source_degree(nodes, weight=weight):
|
| 145 |
+
# handle degree zero average
|
| 146 |
+
if deg == 0:
|
| 147 |
+
avg[n] = 0.0
|
| 148 |
+
continue
|
| 149 |
+
|
| 150 |
+
# we sum over both G_P and G_S, but one of the two is usually empty.
|
| 151 |
+
if weight is None:
|
| 152 |
+
avg[n] = (
|
| 153 |
+
sum(t_deg[nbr] for nbr in G_S[n]) + sum(t_deg[nbr] for nbr in G_P[n])
|
| 154 |
+
) / deg
|
| 155 |
+
else:
|
| 156 |
+
avg[n] = (
|
| 157 |
+
sum(dd.get(weight, 1) * t_deg[nbr] for nbr, dd in G_S[n].items())
|
| 158 |
+
+ sum(dd.get(weight, 1) * t_deg[nbr] for nbr, dd in G_P[n].items())
|
| 159 |
+
) / deg
|
| 160 |
+
return avg
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/assortativity/pairs.py
ADDED
|
@@ -0,0 +1,127 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Generators of x-y pairs of node data."""
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
|
| 5 |
+
__all__ = ["node_attribute_xy", "node_degree_xy"]
|
| 6 |
+
|
| 7 |
+
|
| 8 |
+
@nx._dispatchable(node_attrs="attribute")
|
| 9 |
+
def node_attribute_xy(G, attribute, nodes=None):
|
| 10 |
+
"""Yields 2-tuples of node attribute values for all edges in `G`.
|
| 11 |
+
|
| 12 |
+
This generator yields, for each edge in `G` incident to a node in `nodes`,
|
| 13 |
+
a 2-tuple of form ``(attribute value, attribute value)`` for the parameter
|
| 14 |
+
specified node-attribute.
|
| 15 |
+
|
| 16 |
+
Parameters
|
| 17 |
+
----------
|
| 18 |
+
G: NetworkX graph
|
| 19 |
+
|
| 20 |
+
attribute: key
|
| 21 |
+
The node attribute key.
|
| 22 |
+
|
| 23 |
+
nodes: list or iterable (optional)
|
| 24 |
+
Use only edges that are incident to specified nodes.
|
| 25 |
+
The default is all nodes.
|
| 26 |
+
|
| 27 |
+
Yields
|
| 28 |
+
------
|
| 29 |
+
(x, y): 2-tuple
|
| 30 |
+
Generates 2-tuple of (attribute, attribute) values.
|
| 31 |
+
|
| 32 |
+
Examples
|
| 33 |
+
--------
|
| 34 |
+
>>> G = nx.DiGraph()
|
| 35 |
+
>>> G.add_node(1, color="red")
|
| 36 |
+
>>> G.add_node(2, color="blue")
|
| 37 |
+
>>> G.add_node(3, color="green")
|
| 38 |
+
>>> G.add_edge(1, 2)
|
| 39 |
+
>>> list(nx.node_attribute_xy(G, "color"))
|
| 40 |
+
[('red', 'blue')]
|
| 41 |
+
|
| 42 |
+
Notes
|
| 43 |
+
-----
|
| 44 |
+
For undirected graphs, each edge is produced twice, once for each edge
|
| 45 |
+
representation (u, v) and (v, u), with the exception of self-loop edges
|
| 46 |
+
which only appear once.
|
| 47 |
+
"""
|
| 48 |
+
if nodes is None:
|
| 49 |
+
nodes = set(G)
|
| 50 |
+
else:
|
| 51 |
+
nodes = set(nodes)
|
| 52 |
+
Gnodes = G.nodes
|
| 53 |
+
for u, nbrsdict in G.adjacency():
|
| 54 |
+
if u not in nodes:
|
| 55 |
+
continue
|
| 56 |
+
uattr = Gnodes[u].get(attribute, None)
|
| 57 |
+
if G.is_multigraph():
|
| 58 |
+
for v, keys in nbrsdict.items():
|
| 59 |
+
vattr = Gnodes[v].get(attribute, None)
|
| 60 |
+
for _ in keys:
|
| 61 |
+
yield (uattr, vattr)
|
| 62 |
+
else:
|
| 63 |
+
for v in nbrsdict:
|
| 64 |
+
vattr = Gnodes[v].get(attribute, None)
|
| 65 |
+
yield (uattr, vattr)
|
| 66 |
+
|
| 67 |
+
|
| 68 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 69 |
+
def node_degree_xy(G, x="out", y="in", weight=None, nodes=None):
|
| 70 |
+
"""Yields 2-tuples of ``(degree, degree)`` values for edges in `G`.
|
| 71 |
+
|
| 72 |
+
This generator yields, for each edge in `G` incident to a node in `nodes`,
|
| 73 |
+
a 2-tuple of form ``(degree, degree)``. The node degrees are weighted
|
| 74 |
+
when a `weight` attribute is specified.
|
| 75 |
+
|
| 76 |
+
Parameters
|
| 77 |
+
----------
|
| 78 |
+
G: NetworkX graph
|
| 79 |
+
|
| 80 |
+
x: string ('in','out')
|
| 81 |
+
The degree type for source node (directed graphs only).
|
| 82 |
+
|
| 83 |
+
y: string ('in','out')
|
| 84 |
+
The degree type for target node (directed graphs only).
|
| 85 |
+
|
| 86 |
+
weight: string or None, optional (default=None)
|
| 87 |
+
The edge attribute that holds the numerical value used
|
| 88 |
+
as a weight. If None, then each edge has weight 1.
|
| 89 |
+
The degree is the sum of the edge weights adjacent to the node.
|
| 90 |
+
|
| 91 |
+
nodes: list or iterable (optional)
|
| 92 |
+
Use only edges that are adjacency to specified nodes.
|
| 93 |
+
The default is all nodes.
|
| 94 |
+
|
| 95 |
+
Yields
|
| 96 |
+
------
|
| 97 |
+
(x, y): 2-tuple
|
| 98 |
+
Generates 2-tuple of (degree, degree) values.
|
| 99 |
+
|
| 100 |
+
Examples
|
| 101 |
+
--------
|
| 102 |
+
>>> G = nx.DiGraph()
|
| 103 |
+
>>> G.add_edge(1, 2)
|
| 104 |
+
>>> list(nx.node_degree_xy(G, x="out", y="in"))
|
| 105 |
+
[(1, 1)]
|
| 106 |
+
>>> list(nx.node_degree_xy(G, x="in", y="out"))
|
| 107 |
+
[(0, 0)]
|
| 108 |
+
|
| 109 |
+
Notes
|
| 110 |
+
-----
|
| 111 |
+
For undirected graphs, each edge is produced twice, once for each edge
|
| 112 |
+
representation (u, v) and (v, u), with the exception of self-loop edges
|
| 113 |
+
which only appear once.
|
| 114 |
+
"""
|
| 115 |
+
nodes = set(G) if nodes is None else set(nodes)
|
| 116 |
+
if G.is_directed():
|
| 117 |
+
direction = {"out": G.out_degree, "in": G.in_degree}
|
| 118 |
+
xdeg = direction[x]
|
| 119 |
+
ydeg = direction[y]
|
| 120 |
+
else:
|
| 121 |
+
xdeg = ydeg = G.degree
|
| 122 |
+
|
| 123 |
+
for u, degu in xdeg(nodes, weight=weight):
|
| 124 |
+
# use G.edges to treat multigraphs correctly
|
| 125 |
+
neighbors = (nbr for _, nbr in G.edges(u) if nbr in nodes)
|
| 126 |
+
for _, degv in ydeg(neighbors, weight=weight):
|
| 127 |
+
yield degu, degv
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/asteroidal.py
ADDED
|
@@ -0,0 +1,164 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
Algorithms for asteroidal triples and asteroidal numbers in graphs.
|
| 3 |
+
|
| 4 |
+
An asteroidal triple in a graph G is a set of three non-adjacent vertices
|
| 5 |
+
u, v and w such that there exist a path between any two of them that avoids
|
| 6 |
+
closed neighborhood of the third. More formally, v_j, v_k belongs to the same
|
| 7 |
+
connected component of G - N[v_i], where N[v_i] denotes the closed neighborhood
|
| 8 |
+
of v_i. A graph which does not contain any asteroidal triples is called
|
| 9 |
+
an AT-free graph. The class of AT-free graphs is a graph class for which
|
| 10 |
+
many NP-complete problems are solvable in polynomial time. Amongst them,
|
| 11 |
+
independent set and coloring.
|
| 12 |
+
"""
|
| 13 |
+
|
| 14 |
+
import networkx as nx
|
| 15 |
+
from networkx.utils import not_implemented_for
|
| 16 |
+
|
| 17 |
+
__all__ = ["is_at_free", "find_asteroidal_triple"]
|
| 18 |
+
|
| 19 |
+
|
| 20 |
+
@not_implemented_for("directed")
|
| 21 |
+
@not_implemented_for("multigraph")
|
| 22 |
+
@nx._dispatchable
|
| 23 |
+
def find_asteroidal_triple(G):
|
| 24 |
+
r"""Find an asteroidal triple in the given graph.
|
| 25 |
+
|
| 26 |
+
An asteroidal triple is a triple of non-adjacent vertices such that
|
| 27 |
+
there exists a path between any two of them which avoids the closed
|
| 28 |
+
neighborhood of the third. It checks all independent triples of vertices
|
| 29 |
+
and whether they are an asteroidal triple or not. This is done with the
|
| 30 |
+
help of a data structure called a component structure.
|
| 31 |
+
A component structure encodes information about which vertices belongs to
|
| 32 |
+
the same connected component when the closed neighborhood of a given vertex
|
| 33 |
+
is removed from the graph. The algorithm used to check is the trivial
|
| 34 |
+
one, outlined in [1]_, which has a runtime of
|
| 35 |
+
:math:`O(|V||\overline{E} + |V||E|)`, where the second term is the
|
| 36 |
+
creation of the component structure.
|
| 37 |
+
|
| 38 |
+
Parameters
|
| 39 |
+
----------
|
| 40 |
+
G : NetworkX Graph
|
| 41 |
+
The graph to check whether is AT-free or not
|
| 42 |
+
|
| 43 |
+
Returns
|
| 44 |
+
-------
|
| 45 |
+
list or None
|
| 46 |
+
An asteroidal triple is returned as a list of nodes. If no asteroidal
|
| 47 |
+
triple exists, i.e. the graph is AT-free, then None is returned.
|
| 48 |
+
|
| 49 |
+
Notes
|
| 50 |
+
-----
|
| 51 |
+
The component structure and the algorithm is described in [1]_. The current
|
| 52 |
+
implementation implements the trivial algorithm for simple graphs.
|
| 53 |
+
|
| 54 |
+
References
|
| 55 |
+
----------
|
| 56 |
+
.. [1] Ekkehard Köhler,
|
| 57 |
+
"Recognizing Graphs without asteroidal triples",
|
| 58 |
+
Journal of Discrete Algorithms 2, pages 439-452, 2004.
|
| 59 |
+
https://www.sciencedirect.com/science/article/pii/S157086670400019X
|
| 60 |
+
"""
|
| 61 |
+
V = set(G.nodes)
|
| 62 |
+
|
| 63 |
+
if len(V) < 6:
|
| 64 |
+
# An asteroidal triple cannot exist in a graph with 5 or less vertices.
|
| 65 |
+
return None
|
| 66 |
+
|
| 67 |
+
component_structure = create_component_structure(G)
|
| 68 |
+
|
| 69 |
+
for u, v in nx.non_edges(G):
|
| 70 |
+
u_neighborhood = set(G[u]).union([u])
|
| 71 |
+
v_neighborhood = set(G[v]).union([v])
|
| 72 |
+
union_of_neighborhoods = u_neighborhood.union(v_neighborhood)
|
| 73 |
+
for w in V - union_of_neighborhoods:
|
| 74 |
+
# Check for each pair of vertices whether they belong to the
|
| 75 |
+
# same connected component when the closed neighborhood of the
|
| 76 |
+
# third is removed.
|
| 77 |
+
if (
|
| 78 |
+
component_structure[u][v] == component_structure[u][w]
|
| 79 |
+
and component_structure[v][u] == component_structure[v][w]
|
| 80 |
+
and component_structure[w][u] == component_structure[w][v]
|
| 81 |
+
):
|
| 82 |
+
return [u, v, w]
|
| 83 |
+
return None
|
| 84 |
+
|
| 85 |
+
|
| 86 |
+
@not_implemented_for("directed")
|
| 87 |
+
@not_implemented_for("multigraph")
|
| 88 |
+
@nx._dispatchable
|
| 89 |
+
def is_at_free(G):
|
| 90 |
+
"""Check if a graph is AT-free.
|
| 91 |
+
|
| 92 |
+
The method uses the `find_asteroidal_triple` method to recognize
|
| 93 |
+
an AT-free graph. If no asteroidal triple is found the graph is
|
| 94 |
+
AT-free and True is returned. If at least one asteroidal triple is
|
| 95 |
+
found the graph is not AT-free and False is returned.
|
| 96 |
+
|
| 97 |
+
Parameters
|
| 98 |
+
----------
|
| 99 |
+
G : NetworkX Graph
|
| 100 |
+
The graph to check whether is AT-free or not.
|
| 101 |
+
|
| 102 |
+
Returns
|
| 103 |
+
-------
|
| 104 |
+
bool
|
| 105 |
+
True if G is AT-free and False otherwise.
|
| 106 |
+
|
| 107 |
+
Examples
|
| 108 |
+
--------
|
| 109 |
+
>>> G = nx.Graph([(0, 1), (0, 2), (1, 2), (1, 3), (1, 4), (4, 5)])
|
| 110 |
+
>>> nx.is_at_free(G)
|
| 111 |
+
True
|
| 112 |
+
|
| 113 |
+
>>> G = nx.cycle_graph(6)
|
| 114 |
+
>>> nx.is_at_free(G)
|
| 115 |
+
False
|
| 116 |
+
"""
|
| 117 |
+
return find_asteroidal_triple(G) is None
|
| 118 |
+
|
| 119 |
+
|
| 120 |
+
@not_implemented_for("directed")
|
| 121 |
+
@not_implemented_for("multigraph")
|
| 122 |
+
@nx._dispatchable
|
| 123 |
+
def create_component_structure(G):
|
| 124 |
+
r"""Create component structure for G.
|
| 125 |
+
|
| 126 |
+
A *component structure* is an `nxn` array, denoted `c`, where `n` is
|
| 127 |
+
the number of vertices, where each row and column corresponds to a vertex.
|
| 128 |
+
|
| 129 |
+
.. math::
|
| 130 |
+
c_{uv} = \begin{cases} 0, if v \in N[u] \\
|
| 131 |
+
k, if v \in component k of G \setminus N[u] \end{cases}
|
| 132 |
+
|
| 133 |
+
Where `k` is an arbitrary label for each component. The structure is used
|
| 134 |
+
to simplify the detection of asteroidal triples.
|
| 135 |
+
|
| 136 |
+
Parameters
|
| 137 |
+
----------
|
| 138 |
+
G : NetworkX Graph
|
| 139 |
+
Undirected, simple graph.
|
| 140 |
+
|
| 141 |
+
Returns
|
| 142 |
+
-------
|
| 143 |
+
component_structure : dictionary
|
| 144 |
+
A dictionary of dictionaries, keyed by pairs of vertices.
|
| 145 |
+
|
| 146 |
+
"""
|
| 147 |
+
V = set(G.nodes)
|
| 148 |
+
component_structure = {}
|
| 149 |
+
for v in V:
|
| 150 |
+
label = 0
|
| 151 |
+
closed_neighborhood = set(G[v]).union({v})
|
| 152 |
+
row_dict = {}
|
| 153 |
+
for u in closed_neighborhood:
|
| 154 |
+
row_dict[u] = 0
|
| 155 |
+
|
| 156 |
+
G_reduced = G.subgraph(set(G.nodes) - closed_neighborhood)
|
| 157 |
+
for cc in nx.connected_components(G_reduced):
|
| 158 |
+
label += 1
|
| 159 |
+
for u in cc:
|
| 160 |
+
row_dict[u] = label
|
| 161 |
+
|
| 162 |
+
component_structure[v] = row_dict
|
| 163 |
+
|
| 164 |
+
return component_structure
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/__init__.py
ADDED
|
@@ -0,0 +1,88 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
r"""This module provides functions and operations for bipartite
|
| 2 |
+
graphs. Bipartite graphs `B = (U, V, E)` have two node sets `U,V` and edges in
|
| 3 |
+
`E` that only connect nodes from opposite sets. It is common in the literature
|
| 4 |
+
to use an spatial analogy referring to the two node sets as top and bottom nodes.
|
| 5 |
+
|
| 6 |
+
The bipartite algorithms are not imported into the networkx namespace
|
| 7 |
+
at the top level so the easiest way to use them is with:
|
| 8 |
+
|
| 9 |
+
>>> from networkx.algorithms import bipartite
|
| 10 |
+
|
| 11 |
+
NetworkX does not have a custom bipartite graph class but the Graph()
|
| 12 |
+
or DiGraph() classes can be used to represent bipartite graphs. However,
|
| 13 |
+
you have to keep track of which set each node belongs to, and make
|
| 14 |
+
sure that there is no edge between nodes of the same set. The convention used
|
| 15 |
+
in NetworkX is to use a node attribute named `bipartite` with values 0 or 1 to
|
| 16 |
+
identify the sets each node belongs to. This convention is not enforced in
|
| 17 |
+
the source code of bipartite functions, it's only a recommendation.
|
| 18 |
+
|
| 19 |
+
For example:
|
| 20 |
+
|
| 21 |
+
>>> B = nx.Graph()
|
| 22 |
+
>>> # Add nodes with the node attribute "bipartite"
|
| 23 |
+
>>> B.add_nodes_from([1, 2, 3, 4], bipartite=0)
|
| 24 |
+
>>> B.add_nodes_from(["a", "b", "c"], bipartite=1)
|
| 25 |
+
>>> # Add edges only between nodes of opposite node sets
|
| 26 |
+
>>> B.add_edges_from([(1, "a"), (1, "b"), (2, "b"), (2, "c"), (3, "c"), (4, "a")])
|
| 27 |
+
|
| 28 |
+
Many algorithms of the bipartite module of NetworkX require, as an argument, a
|
| 29 |
+
container with all the nodes that belong to one set, in addition to the bipartite
|
| 30 |
+
graph `B`. The functions in the bipartite package do not check that the node set
|
| 31 |
+
is actually correct nor that the input graph is actually bipartite.
|
| 32 |
+
If `B` is connected, you can find the two node sets using a two-coloring
|
| 33 |
+
algorithm:
|
| 34 |
+
|
| 35 |
+
>>> nx.is_connected(B)
|
| 36 |
+
True
|
| 37 |
+
>>> bottom_nodes, top_nodes = bipartite.sets(B)
|
| 38 |
+
|
| 39 |
+
However, if the input graph is not connected, there are more than one possible
|
| 40 |
+
colorations. This is the reason why we require the user to pass a container
|
| 41 |
+
with all nodes of one bipartite node set as an argument to most bipartite
|
| 42 |
+
functions. In the face of ambiguity, we refuse the temptation to guess and
|
| 43 |
+
raise an :exc:`AmbiguousSolution <networkx.AmbiguousSolution>`
|
| 44 |
+
Exception if the input graph for
|
| 45 |
+
:func:`bipartite.sets <networkx.algorithms.bipartite.basic.sets>`
|
| 46 |
+
is disconnected.
|
| 47 |
+
|
| 48 |
+
Using the `bipartite` node attribute, you can easily get the two node sets:
|
| 49 |
+
|
| 50 |
+
>>> top_nodes = {n for n, d in B.nodes(data=True) if d["bipartite"] == 0}
|
| 51 |
+
>>> bottom_nodes = set(B) - top_nodes
|
| 52 |
+
|
| 53 |
+
So you can easily use the bipartite algorithms that require, as an argument, a
|
| 54 |
+
container with all nodes that belong to one node set:
|
| 55 |
+
|
| 56 |
+
>>> print(round(bipartite.density(B, bottom_nodes), 2))
|
| 57 |
+
0.5
|
| 58 |
+
>>> G = bipartite.projected_graph(B, top_nodes)
|
| 59 |
+
|
| 60 |
+
All bipartite graph generators in NetworkX build bipartite graphs with the
|
| 61 |
+
`bipartite` node attribute. Thus, you can use the same approach:
|
| 62 |
+
|
| 63 |
+
>>> RB = bipartite.random_graph(5, 7, 0.2)
|
| 64 |
+
>>> RB_top = {n for n, d in RB.nodes(data=True) if d["bipartite"] == 0}
|
| 65 |
+
>>> RB_bottom = set(RB) - RB_top
|
| 66 |
+
>>> list(RB_top)
|
| 67 |
+
[0, 1, 2, 3, 4]
|
| 68 |
+
>>> list(RB_bottom)
|
| 69 |
+
[5, 6, 7, 8, 9, 10, 11]
|
| 70 |
+
|
| 71 |
+
For other bipartite graph generators see
|
| 72 |
+
:mod:`Generators <networkx.algorithms.bipartite.generators>`.
|
| 73 |
+
|
| 74 |
+
"""
|
| 75 |
+
|
| 76 |
+
from networkx.algorithms.bipartite.basic import *
|
| 77 |
+
from networkx.algorithms.bipartite.centrality import *
|
| 78 |
+
from networkx.algorithms.bipartite.cluster import *
|
| 79 |
+
from networkx.algorithms.bipartite.covering import *
|
| 80 |
+
from networkx.algorithms.bipartite.edgelist import *
|
| 81 |
+
from networkx.algorithms.bipartite.matching import *
|
| 82 |
+
from networkx.algorithms.bipartite.matrix import *
|
| 83 |
+
from networkx.algorithms.bipartite.projection import *
|
| 84 |
+
from networkx.algorithms.bipartite.redundancy import *
|
| 85 |
+
from networkx.algorithms.bipartite.spectral import *
|
| 86 |
+
from networkx.algorithms.bipartite.generators import *
|
| 87 |
+
from networkx.algorithms.bipartite.extendability import *
|
| 88 |
+
from networkx.algorithms.bipartite.link_analysis import *
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/basic.py
ADDED
|
@@ -0,0 +1,322 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
==========================
|
| 3 |
+
Bipartite Graph Algorithms
|
| 4 |
+
==========================
|
| 5 |
+
"""
|
| 6 |
+
|
| 7 |
+
import networkx as nx
|
| 8 |
+
from networkx.algorithms.components import connected_components
|
| 9 |
+
from networkx.exception import AmbiguousSolution
|
| 10 |
+
|
| 11 |
+
__all__ = [
|
| 12 |
+
"is_bipartite",
|
| 13 |
+
"is_bipartite_node_set",
|
| 14 |
+
"color",
|
| 15 |
+
"sets",
|
| 16 |
+
"density",
|
| 17 |
+
"degrees",
|
| 18 |
+
]
|
| 19 |
+
|
| 20 |
+
|
| 21 |
+
@nx._dispatchable
|
| 22 |
+
def color(G):
|
| 23 |
+
"""Returns a two-coloring of the graph.
|
| 24 |
+
|
| 25 |
+
Raises an exception if the graph is not bipartite.
|
| 26 |
+
|
| 27 |
+
Parameters
|
| 28 |
+
----------
|
| 29 |
+
G : NetworkX graph
|
| 30 |
+
|
| 31 |
+
Returns
|
| 32 |
+
-------
|
| 33 |
+
color : dictionary
|
| 34 |
+
A dictionary keyed by node with a 1 or 0 as data for each node color.
|
| 35 |
+
|
| 36 |
+
Raises
|
| 37 |
+
------
|
| 38 |
+
NetworkXError
|
| 39 |
+
If the graph is not two-colorable.
|
| 40 |
+
|
| 41 |
+
Examples
|
| 42 |
+
--------
|
| 43 |
+
>>> from networkx.algorithms import bipartite
|
| 44 |
+
>>> G = nx.path_graph(4)
|
| 45 |
+
>>> c = bipartite.color(G)
|
| 46 |
+
>>> print(c)
|
| 47 |
+
{0: 1, 1: 0, 2: 1, 3: 0}
|
| 48 |
+
|
| 49 |
+
You can use this to set a node attribute indicating the bipartite set:
|
| 50 |
+
|
| 51 |
+
>>> nx.set_node_attributes(G, c, "bipartite")
|
| 52 |
+
>>> print(G.nodes[0]["bipartite"])
|
| 53 |
+
1
|
| 54 |
+
>>> print(G.nodes[1]["bipartite"])
|
| 55 |
+
0
|
| 56 |
+
"""
|
| 57 |
+
if G.is_directed():
|
| 58 |
+
import itertools
|
| 59 |
+
|
| 60 |
+
def neighbors(v):
|
| 61 |
+
return itertools.chain.from_iterable([G.predecessors(v), G.successors(v)])
|
| 62 |
+
|
| 63 |
+
else:
|
| 64 |
+
neighbors = G.neighbors
|
| 65 |
+
|
| 66 |
+
color = {}
|
| 67 |
+
for n in G: # handle disconnected graphs
|
| 68 |
+
if n in color or len(G[n]) == 0: # skip isolates
|
| 69 |
+
continue
|
| 70 |
+
queue = [n]
|
| 71 |
+
color[n] = 1 # nodes seen with color (1 or 0)
|
| 72 |
+
while queue:
|
| 73 |
+
v = queue.pop()
|
| 74 |
+
c = 1 - color[v] # opposite color of node v
|
| 75 |
+
for w in neighbors(v):
|
| 76 |
+
if w in color:
|
| 77 |
+
if color[w] == color[v]:
|
| 78 |
+
raise nx.NetworkXError("Graph is not bipartite.")
|
| 79 |
+
else:
|
| 80 |
+
color[w] = c
|
| 81 |
+
queue.append(w)
|
| 82 |
+
# color isolates with 0
|
| 83 |
+
color.update(dict.fromkeys(nx.isolates(G), 0))
|
| 84 |
+
return color
|
| 85 |
+
|
| 86 |
+
|
| 87 |
+
@nx._dispatchable
|
| 88 |
+
def is_bipartite(G):
|
| 89 |
+
"""Returns True if graph G is bipartite, False if not.
|
| 90 |
+
|
| 91 |
+
Parameters
|
| 92 |
+
----------
|
| 93 |
+
G : NetworkX graph
|
| 94 |
+
|
| 95 |
+
Examples
|
| 96 |
+
--------
|
| 97 |
+
>>> from networkx.algorithms import bipartite
|
| 98 |
+
>>> G = nx.path_graph(4)
|
| 99 |
+
>>> print(bipartite.is_bipartite(G))
|
| 100 |
+
True
|
| 101 |
+
|
| 102 |
+
See Also
|
| 103 |
+
--------
|
| 104 |
+
color, is_bipartite_node_set
|
| 105 |
+
"""
|
| 106 |
+
try:
|
| 107 |
+
color(G)
|
| 108 |
+
return True
|
| 109 |
+
except nx.NetworkXError:
|
| 110 |
+
return False
|
| 111 |
+
|
| 112 |
+
|
| 113 |
+
@nx._dispatchable
|
| 114 |
+
def is_bipartite_node_set(G, nodes):
|
| 115 |
+
"""Returns True if nodes and G/nodes are a bipartition of G.
|
| 116 |
+
|
| 117 |
+
Parameters
|
| 118 |
+
----------
|
| 119 |
+
G : NetworkX graph
|
| 120 |
+
|
| 121 |
+
nodes: list or container
|
| 122 |
+
Check if nodes are a one of a bipartite set.
|
| 123 |
+
|
| 124 |
+
Examples
|
| 125 |
+
--------
|
| 126 |
+
>>> from networkx.algorithms import bipartite
|
| 127 |
+
>>> G = nx.path_graph(4)
|
| 128 |
+
>>> X = set([1, 3])
|
| 129 |
+
>>> bipartite.is_bipartite_node_set(G, X)
|
| 130 |
+
True
|
| 131 |
+
|
| 132 |
+
Notes
|
| 133 |
+
-----
|
| 134 |
+
An exception is raised if the input nodes are not distinct, because in this
|
| 135 |
+
case some bipartite algorithms will yield incorrect results.
|
| 136 |
+
For connected graphs the bipartite sets are unique. This function handles
|
| 137 |
+
disconnected graphs.
|
| 138 |
+
"""
|
| 139 |
+
S = set(nodes)
|
| 140 |
+
|
| 141 |
+
if len(S) < len(nodes):
|
| 142 |
+
# this should maybe just return False?
|
| 143 |
+
raise AmbiguousSolution(
|
| 144 |
+
"The input node set contains duplicates.\n"
|
| 145 |
+
"This may lead to incorrect results when using it in bipartite algorithms.\n"
|
| 146 |
+
"Consider using set(nodes) as the input"
|
| 147 |
+
)
|
| 148 |
+
|
| 149 |
+
for CC in (G.subgraph(c).copy() for c in connected_components(G)):
|
| 150 |
+
X, Y = sets(CC)
|
| 151 |
+
if not (
|
| 152 |
+
(X.issubset(S) and Y.isdisjoint(S)) or (Y.issubset(S) and X.isdisjoint(S))
|
| 153 |
+
):
|
| 154 |
+
return False
|
| 155 |
+
return True
|
| 156 |
+
|
| 157 |
+
|
| 158 |
+
@nx._dispatchable
|
| 159 |
+
def sets(G, top_nodes=None):
|
| 160 |
+
"""Returns bipartite node sets of graph G.
|
| 161 |
+
|
| 162 |
+
Raises an exception if the graph is not bipartite or if the input
|
| 163 |
+
graph is disconnected and thus more than one valid solution exists.
|
| 164 |
+
See :mod:`bipartite documentation <networkx.algorithms.bipartite>`
|
| 165 |
+
for further details on how bipartite graphs are handled in NetworkX.
|
| 166 |
+
|
| 167 |
+
Parameters
|
| 168 |
+
----------
|
| 169 |
+
G : NetworkX graph
|
| 170 |
+
|
| 171 |
+
top_nodes : container, optional
|
| 172 |
+
Container with all nodes in one bipartite node set. If not supplied
|
| 173 |
+
it will be computed. But if more than one solution exists an exception
|
| 174 |
+
will be raised.
|
| 175 |
+
|
| 176 |
+
Returns
|
| 177 |
+
-------
|
| 178 |
+
X : set
|
| 179 |
+
Nodes from one side of the bipartite graph.
|
| 180 |
+
Y : set
|
| 181 |
+
Nodes from the other side.
|
| 182 |
+
|
| 183 |
+
Raises
|
| 184 |
+
------
|
| 185 |
+
AmbiguousSolution
|
| 186 |
+
Raised if the input bipartite graph is disconnected and no container
|
| 187 |
+
with all nodes in one bipartite set is provided. When determining
|
| 188 |
+
the nodes in each bipartite set more than one valid solution is
|
| 189 |
+
possible if the input graph is disconnected.
|
| 190 |
+
NetworkXError
|
| 191 |
+
Raised if the input graph is not bipartite.
|
| 192 |
+
|
| 193 |
+
Examples
|
| 194 |
+
--------
|
| 195 |
+
>>> from networkx.algorithms import bipartite
|
| 196 |
+
>>> G = nx.path_graph(4)
|
| 197 |
+
>>> X, Y = bipartite.sets(G)
|
| 198 |
+
>>> list(X)
|
| 199 |
+
[0, 2]
|
| 200 |
+
>>> list(Y)
|
| 201 |
+
[1, 3]
|
| 202 |
+
|
| 203 |
+
See Also
|
| 204 |
+
--------
|
| 205 |
+
color
|
| 206 |
+
|
| 207 |
+
"""
|
| 208 |
+
if G.is_directed():
|
| 209 |
+
is_connected = nx.is_weakly_connected
|
| 210 |
+
else:
|
| 211 |
+
is_connected = nx.is_connected
|
| 212 |
+
if top_nodes is not None:
|
| 213 |
+
X = set(top_nodes)
|
| 214 |
+
Y = set(G) - X
|
| 215 |
+
else:
|
| 216 |
+
if not is_connected(G):
|
| 217 |
+
msg = "Disconnected graph: Ambiguous solution for bipartite sets."
|
| 218 |
+
raise nx.AmbiguousSolution(msg)
|
| 219 |
+
c = color(G)
|
| 220 |
+
X = {n for n, is_top in c.items() if is_top}
|
| 221 |
+
Y = {n for n, is_top in c.items() if not is_top}
|
| 222 |
+
return (X, Y)
|
| 223 |
+
|
| 224 |
+
|
| 225 |
+
@nx._dispatchable(graphs="B")
|
| 226 |
+
def density(B, nodes):
|
| 227 |
+
"""Returns density of bipartite graph B.
|
| 228 |
+
|
| 229 |
+
Parameters
|
| 230 |
+
----------
|
| 231 |
+
B : NetworkX graph
|
| 232 |
+
|
| 233 |
+
nodes: list or container
|
| 234 |
+
Nodes in one node set of the bipartite graph.
|
| 235 |
+
|
| 236 |
+
Returns
|
| 237 |
+
-------
|
| 238 |
+
d : float
|
| 239 |
+
The bipartite density
|
| 240 |
+
|
| 241 |
+
Examples
|
| 242 |
+
--------
|
| 243 |
+
>>> from networkx.algorithms import bipartite
|
| 244 |
+
>>> G = nx.complete_bipartite_graph(3, 2)
|
| 245 |
+
>>> X = set([0, 1, 2])
|
| 246 |
+
>>> bipartite.density(G, X)
|
| 247 |
+
1.0
|
| 248 |
+
>>> Y = set([3, 4])
|
| 249 |
+
>>> bipartite.density(G, Y)
|
| 250 |
+
1.0
|
| 251 |
+
|
| 252 |
+
Notes
|
| 253 |
+
-----
|
| 254 |
+
The container of nodes passed as argument must contain all nodes
|
| 255 |
+
in one of the two bipartite node sets to avoid ambiguity in the
|
| 256 |
+
case of disconnected graphs.
|
| 257 |
+
See :mod:`bipartite documentation <networkx.algorithms.bipartite>`
|
| 258 |
+
for further details on how bipartite graphs are handled in NetworkX.
|
| 259 |
+
|
| 260 |
+
See Also
|
| 261 |
+
--------
|
| 262 |
+
color
|
| 263 |
+
"""
|
| 264 |
+
n = len(B)
|
| 265 |
+
m = nx.number_of_edges(B)
|
| 266 |
+
nb = len(nodes)
|
| 267 |
+
nt = n - nb
|
| 268 |
+
if m == 0: # includes cases n==0 and n==1
|
| 269 |
+
d = 0.0
|
| 270 |
+
else:
|
| 271 |
+
if B.is_directed():
|
| 272 |
+
d = m / (2 * nb * nt)
|
| 273 |
+
else:
|
| 274 |
+
d = m / (nb * nt)
|
| 275 |
+
return d
|
| 276 |
+
|
| 277 |
+
|
| 278 |
+
@nx._dispatchable(graphs="B", edge_attrs="weight")
|
| 279 |
+
def degrees(B, nodes, weight=None):
|
| 280 |
+
"""Returns the degrees of the two node sets in the bipartite graph B.
|
| 281 |
+
|
| 282 |
+
Parameters
|
| 283 |
+
----------
|
| 284 |
+
B : NetworkX graph
|
| 285 |
+
|
| 286 |
+
nodes: list or container
|
| 287 |
+
Nodes in one node set of the bipartite graph.
|
| 288 |
+
|
| 289 |
+
weight : string or None, optional (default=None)
|
| 290 |
+
The edge attribute that holds the numerical value used as a weight.
|
| 291 |
+
If None, then each edge has weight 1.
|
| 292 |
+
The degree is the sum of the edge weights adjacent to the node.
|
| 293 |
+
|
| 294 |
+
Returns
|
| 295 |
+
-------
|
| 296 |
+
(degX,degY) : tuple of dictionaries
|
| 297 |
+
The degrees of the two bipartite sets as dictionaries keyed by node.
|
| 298 |
+
|
| 299 |
+
Examples
|
| 300 |
+
--------
|
| 301 |
+
>>> from networkx.algorithms import bipartite
|
| 302 |
+
>>> G = nx.complete_bipartite_graph(3, 2)
|
| 303 |
+
>>> Y = set([3, 4])
|
| 304 |
+
>>> degX, degY = bipartite.degrees(G, Y)
|
| 305 |
+
>>> dict(degX)
|
| 306 |
+
{0: 2, 1: 2, 2: 2}
|
| 307 |
+
|
| 308 |
+
Notes
|
| 309 |
+
-----
|
| 310 |
+
The container of nodes passed as argument must contain all nodes
|
| 311 |
+
in one of the two bipartite node sets to avoid ambiguity in the
|
| 312 |
+
case of disconnected graphs.
|
| 313 |
+
See :mod:`bipartite documentation <networkx.algorithms.bipartite>`
|
| 314 |
+
for further details on how bipartite graphs are handled in NetworkX.
|
| 315 |
+
|
| 316 |
+
See Also
|
| 317 |
+
--------
|
| 318 |
+
color, density
|
| 319 |
+
"""
|
| 320 |
+
bottom = set(nodes)
|
| 321 |
+
top = set(B) - bottom
|
| 322 |
+
return (B.degree(top, weight), B.degree(bottom, weight))
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/centrality.py
ADDED
|
@@ -0,0 +1,290 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
import networkx as nx
|
| 2 |
+
|
| 3 |
+
__all__ = ["degree_centrality", "betweenness_centrality", "closeness_centrality"]
|
| 4 |
+
|
| 5 |
+
|
| 6 |
+
@nx._dispatchable(name="bipartite_degree_centrality")
|
| 7 |
+
def degree_centrality(G, nodes):
|
| 8 |
+
r"""Compute the degree centrality for nodes in a bipartite network.
|
| 9 |
+
|
| 10 |
+
The degree centrality for a node `v` is the fraction of nodes
|
| 11 |
+
connected to it.
|
| 12 |
+
|
| 13 |
+
Parameters
|
| 14 |
+
----------
|
| 15 |
+
G : graph
|
| 16 |
+
A bipartite network
|
| 17 |
+
|
| 18 |
+
nodes : list or container
|
| 19 |
+
Container with all nodes in one bipartite node set.
|
| 20 |
+
|
| 21 |
+
Returns
|
| 22 |
+
-------
|
| 23 |
+
centrality : dictionary
|
| 24 |
+
Dictionary keyed by node with bipartite degree centrality as the value.
|
| 25 |
+
|
| 26 |
+
Examples
|
| 27 |
+
--------
|
| 28 |
+
>>> G = nx.wheel_graph(5)
|
| 29 |
+
>>> top_nodes = {0, 1, 2}
|
| 30 |
+
>>> nx.bipartite.degree_centrality(G, nodes=top_nodes)
|
| 31 |
+
{0: 2.0, 1: 1.5, 2: 1.5, 3: 1.0, 4: 1.0}
|
| 32 |
+
|
| 33 |
+
See Also
|
| 34 |
+
--------
|
| 35 |
+
betweenness_centrality
|
| 36 |
+
closeness_centrality
|
| 37 |
+
:func:`~networkx.algorithms.bipartite.basic.sets`
|
| 38 |
+
:func:`~networkx.algorithms.bipartite.basic.is_bipartite`
|
| 39 |
+
|
| 40 |
+
Notes
|
| 41 |
+
-----
|
| 42 |
+
The nodes input parameter must contain all nodes in one bipartite node set,
|
| 43 |
+
but the dictionary returned contains all nodes from both bipartite node
|
| 44 |
+
sets. See :mod:`bipartite documentation <networkx.algorithms.bipartite>`
|
| 45 |
+
for further details on how bipartite graphs are handled in NetworkX.
|
| 46 |
+
|
| 47 |
+
For unipartite networks, the degree centrality values are
|
| 48 |
+
normalized by dividing by the maximum possible degree (which is
|
| 49 |
+
`n-1` where `n` is the number of nodes in G).
|
| 50 |
+
|
| 51 |
+
In the bipartite case, the maximum possible degree of a node in a
|
| 52 |
+
bipartite node set is the number of nodes in the opposite node set
|
| 53 |
+
[1]_. The degree centrality for a node `v` in the bipartite
|
| 54 |
+
sets `U` with `n` nodes and `V` with `m` nodes is
|
| 55 |
+
|
| 56 |
+
.. math::
|
| 57 |
+
|
| 58 |
+
d_{v} = \frac{deg(v)}{m}, \mbox{for} v \in U ,
|
| 59 |
+
|
| 60 |
+
d_{v} = \frac{deg(v)}{n}, \mbox{for} v \in V ,
|
| 61 |
+
|
| 62 |
+
|
| 63 |
+
where `deg(v)` is the degree of node `v`.
|
| 64 |
+
|
| 65 |
+
References
|
| 66 |
+
----------
|
| 67 |
+
.. [1] Borgatti, S.P. and Halgin, D. In press. "Analyzing Affiliation
|
| 68 |
+
Networks". In Carrington, P. and Scott, J. (eds) The Sage Handbook
|
| 69 |
+
of Social Network Analysis. Sage Publications.
|
| 70 |
+
https://dx.doi.org/10.4135/9781446294413.n28
|
| 71 |
+
"""
|
| 72 |
+
top = set(nodes)
|
| 73 |
+
bottom = set(G) - top
|
| 74 |
+
s = 1.0 / len(bottom)
|
| 75 |
+
centrality = {n: d * s for n, d in G.degree(top)}
|
| 76 |
+
s = 1.0 / len(top)
|
| 77 |
+
centrality.update({n: d * s for n, d in G.degree(bottom)})
|
| 78 |
+
return centrality
|
| 79 |
+
|
| 80 |
+
|
| 81 |
+
@nx._dispatchable(name="bipartite_betweenness_centrality")
|
| 82 |
+
def betweenness_centrality(G, nodes):
|
| 83 |
+
r"""Compute betweenness centrality for nodes in a bipartite network.
|
| 84 |
+
|
| 85 |
+
Betweenness centrality of a node `v` is the sum of the
|
| 86 |
+
fraction of all-pairs shortest paths that pass through `v`.
|
| 87 |
+
|
| 88 |
+
Values of betweenness are normalized by the maximum possible
|
| 89 |
+
value which for bipartite graphs is limited by the relative size
|
| 90 |
+
of the two node sets [1]_.
|
| 91 |
+
|
| 92 |
+
Let `n` be the number of nodes in the node set `U` and
|
| 93 |
+
`m` be the number of nodes in the node set `V`, then
|
| 94 |
+
nodes in `U` are normalized by dividing by
|
| 95 |
+
|
| 96 |
+
.. math::
|
| 97 |
+
|
| 98 |
+
\frac{1}{2} [m^2 (s + 1)^2 + m (s + 1)(2t - s - 1) - t (2s - t + 3)] ,
|
| 99 |
+
|
| 100 |
+
where
|
| 101 |
+
|
| 102 |
+
.. math::
|
| 103 |
+
|
| 104 |
+
s = (n - 1) \div m , t = (n - 1) \mod m ,
|
| 105 |
+
|
| 106 |
+
and nodes in `V` are normalized by dividing by
|
| 107 |
+
|
| 108 |
+
.. math::
|
| 109 |
+
|
| 110 |
+
\frac{1}{2} [n^2 (p + 1)^2 + n (p + 1)(2r - p - 1) - r (2p - r + 3)] ,
|
| 111 |
+
|
| 112 |
+
where,
|
| 113 |
+
|
| 114 |
+
.. math::
|
| 115 |
+
|
| 116 |
+
p = (m - 1) \div n , r = (m - 1) \mod n .
|
| 117 |
+
|
| 118 |
+
Parameters
|
| 119 |
+
----------
|
| 120 |
+
G : graph
|
| 121 |
+
A bipartite graph
|
| 122 |
+
|
| 123 |
+
nodes : list or container
|
| 124 |
+
Container with all nodes in one bipartite node set.
|
| 125 |
+
|
| 126 |
+
Returns
|
| 127 |
+
-------
|
| 128 |
+
betweenness : dictionary
|
| 129 |
+
Dictionary keyed by node with bipartite betweenness centrality
|
| 130 |
+
as the value.
|
| 131 |
+
|
| 132 |
+
Examples
|
| 133 |
+
--------
|
| 134 |
+
>>> G = nx.cycle_graph(4)
|
| 135 |
+
>>> top_nodes = {1, 2}
|
| 136 |
+
>>> nx.bipartite.betweenness_centrality(G, nodes=top_nodes)
|
| 137 |
+
{0: 0.25, 1: 0.25, 2: 0.25, 3: 0.25}
|
| 138 |
+
|
| 139 |
+
See Also
|
| 140 |
+
--------
|
| 141 |
+
degree_centrality
|
| 142 |
+
closeness_centrality
|
| 143 |
+
:func:`~networkx.algorithms.bipartite.basic.sets`
|
| 144 |
+
:func:`~networkx.algorithms.bipartite.basic.is_bipartite`
|
| 145 |
+
|
| 146 |
+
Notes
|
| 147 |
+
-----
|
| 148 |
+
The nodes input parameter must contain all nodes in one bipartite node set,
|
| 149 |
+
but the dictionary returned contains all nodes from both node sets.
|
| 150 |
+
See :mod:`bipartite documentation <networkx.algorithms.bipartite>`
|
| 151 |
+
for further details on how bipartite graphs are handled in NetworkX.
|
| 152 |
+
|
| 153 |
+
|
| 154 |
+
References
|
| 155 |
+
----------
|
| 156 |
+
.. [1] Borgatti, S.P. and Halgin, D. In press. "Analyzing Affiliation
|
| 157 |
+
Networks". In Carrington, P. and Scott, J. (eds) The Sage Handbook
|
| 158 |
+
of Social Network Analysis. Sage Publications.
|
| 159 |
+
https://dx.doi.org/10.4135/9781446294413.n28
|
| 160 |
+
"""
|
| 161 |
+
top = set(nodes)
|
| 162 |
+
bottom = set(G) - top
|
| 163 |
+
n = len(top)
|
| 164 |
+
m = len(bottom)
|
| 165 |
+
s, t = divmod(n - 1, m)
|
| 166 |
+
bet_max_top = (
|
| 167 |
+
((m**2) * ((s + 1) ** 2))
|
| 168 |
+
+ (m * (s + 1) * (2 * t - s - 1))
|
| 169 |
+
- (t * ((2 * s) - t + 3))
|
| 170 |
+
) / 2.0
|
| 171 |
+
p, r = divmod(m - 1, n)
|
| 172 |
+
bet_max_bot = (
|
| 173 |
+
((n**2) * ((p + 1) ** 2))
|
| 174 |
+
+ (n * (p + 1) * (2 * r - p - 1))
|
| 175 |
+
- (r * ((2 * p) - r + 3))
|
| 176 |
+
) / 2.0
|
| 177 |
+
betweenness = nx.betweenness_centrality(G, normalized=False, weight=None)
|
| 178 |
+
for node in top:
|
| 179 |
+
betweenness[node] /= bet_max_top
|
| 180 |
+
for node in bottom:
|
| 181 |
+
betweenness[node] /= bet_max_bot
|
| 182 |
+
return betweenness
|
| 183 |
+
|
| 184 |
+
|
| 185 |
+
@nx._dispatchable(name="bipartite_closeness_centrality")
|
| 186 |
+
def closeness_centrality(G, nodes, normalized=True):
|
| 187 |
+
r"""Compute the closeness centrality for nodes in a bipartite network.
|
| 188 |
+
|
| 189 |
+
The closeness of a node is the distance to all other nodes in the
|
| 190 |
+
graph or in the case that the graph is not connected to all other nodes
|
| 191 |
+
in the connected component containing that node.
|
| 192 |
+
|
| 193 |
+
Parameters
|
| 194 |
+
----------
|
| 195 |
+
G : graph
|
| 196 |
+
A bipartite network
|
| 197 |
+
|
| 198 |
+
nodes : list or container
|
| 199 |
+
Container with all nodes in one bipartite node set.
|
| 200 |
+
|
| 201 |
+
normalized : bool, optional
|
| 202 |
+
If True (default) normalize by connected component size.
|
| 203 |
+
|
| 204 |
+
Returns
|
| 205 |
+
-------
|
| 206 |
+
closeness : dictionary
|
| 207 |
+
Dictionary keyed by node with bipartite closeness centrality
|
| 208 |
+
as the value.
|
| 209 |
+
|
| 210 |
+
Examples
|
| 211 |
+
--------
|
| 212 |
+
>>> G = nx.wheel_graph(5)
|
| 213 |
+
>>> top_nodes = {0, 1, 2}
|
| 214 |
+
>>> nx.bipartite.closeness_centrality(G, nodes=top_nodes)
|
| 215 |
+
{0: 1.5, 1: 1.2, 2: 1.2, 3: 1.0, 4: 1.0}
|
| 216 |
+
|
| 217 |
+
See Also
|
| 218 |
+
--------
|
| 219 |
+
betweenness_centrality
|
| 220 |
+
degree_centrality
|
| 221 |
+
:func:`~networkx.algorithms.bipartite.basic.sets`
|
| 222 |
+
:func:`~networkx.algorithms.bipartite.basic.is_bipartite`
|
| 223 |
+
|
| 224 |
+
Notes
|
| 225 |
+
-----
|
| 226 |
+
The nodes input parameter must contain all nodes in one bipartite node set,
|
| 227 |
+
but the dictionary returned contains all nodes from both node sets.
|
| 228 |
+
See :mod:`bipartite documentation <networkx.algorithms.bipartite>`
|
| 229 |
+
for further details on how bipartite graphs are handled in NetworkX.
|
| 230 |
+
|
| 231 |
+
|
| 232 |
+
Closeness centrality is normalized by the minimum distance possible.
|
| 233 |
+
In the bipartite case the minimum distance for a node in one bipartite
|
| 234 |
+
node set is 1 from all nodes in the other node set and 2 from all
|
| 235 |
+
other nodes in its own set [1]_. Thus the closeness centrality
|
| 236 |
+
for node `v` in the two bipartite sets `U` with
|
| 237 |
+
`n` nodes and `V` with `m` nodes is
|
| 238 |
+
|
| 239 |
+
.. math::
|
| 240 |
+
|
| 241 |
+
c_{v} = \frac{m + 2(n - 1)}{d}, \mbox{for} v \in U,
|
| 242 |
+
|
| 243 |
+
c_{v} = \frac{n + 2(m - 1)}{d}, \mbox{for} v \in V,
|
| 244 |
+
|
| 245 |
+
where `d` is the sum of the distances from `v` to all
|
| 246 |
+
other nodes.
|
| 247 |
+
|
| 248 |
+
Higher values of closeness indicate higher centrality.
|
| 249 |
+
|
| 250 |
+
As in the unipartite case, setting normalized=True causes the
|
| 251 |
+
values to normalized further to n-1 / size(G)-1 where n is the
|
| 252 |
+
number of nodes in the connected part of graph containing the
|
| 253 |
+
node. If the graph is not completely connected, this algorithm
|
| 254 |
+
computes the closeness centrality for each connected part
|
| 255 |
+
separately.
|
| 256 |
+
|
| 257 |
+
References
|
| 258 |
+
----------
|
| 259 |
+
.. [1] Borgatti, S.P. and Halgin, D. In press. "Analyzing Affiliation
|
| 260 |
+
Networks". In Carrington, P. and Scott, J. (eds) The Sage Handbook
|
| 261 |
+
of Social Network Analysis. Sage Publications.
|
| 262 |
+
https://dx.doi.org/10.4135/9781446294413.n28
|
| 263 |
+
"""
|
| 264 |
+
closeness = {}
|
| 265 |
+
path_length = nx.single_source_shortest_path_length
|
| 266 |
+
top = set(nodes)
|
| 267 |
+
bottom = set(G) - top
|
| 268 |
+
n = len(top)
|
| 269 |
+
m = len(bottom)
|
| 270 |
+
for node in top:
|
| 271 |
+
sp = dict(path_length(G, node))
|
| 272 |
+
totsp = sum(sp.values())
|
| 273 |
+
if totsp > 0.0 and len(G) > 1:
|
| 274 |
+
closeness[node] = (m + 2 * (n - 1)) / totsp
|
| 275 |
+
if normalized:
|
| 276 |
+
s = (len(sp) - 1) / (len(G) - 1)
|
| 277 |
+
closeness[node] *= s
|
| 278 |
+
else:
|
| 279 |
+
closeness[node] = 0.0
|
| 280 |
+
for node in bottom:
|
| 281 |
+
sp = dict(path_length(G, node))
|
| 282 |
+
totsp = sum(sp.values())
|
| 283 |
+
if totsp > 0.0 and len(G) > 1:
|
| 284 |
+
closeness[node] = (n + 2 * (m - 1)) / totsp
|
| 285 |
+
if normalized:
|
| 286 |
+
s = (len(sp) - 1) / (len(G) - 1)
|
| 287 |
+
closeness[node] *= s
|
| 288 |
+
else:
|
| 289 |
+
closeness[node] = 0.0
|
| 290 |
+
return closeness
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/cluster.py
ADDED
|
@@ -0,0 +1,289 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for computing clustering of pairs"""
|
| 2 |
+
|
| 3 |
+
import itertools
|
| 4 |
+
|
| 5 |
+
import networkx as nx
|
| 6 |
+
|
| 7 |
+
__all__ = [
|
| 8 |
+
"clustering",
|
| 9 |
+
"average_clustering",
|
| 10 |
+
"latapy_clustering",
|
| 11 |
+
"robins_alexander_clustering",
|
| 12 |
+
]
|
| 13 |
+
|
| 14 |
+
|
| 15 |
+
def cc_dot(nu, nv):
|
| 16 |
+
return len(nu & nv) / len(nu | nv)
|
| 17 |
+
|
| 18 |
+
|
| 19 |
+
def cc_max(nu, nv):
|
| 20 |
+
return len(nu & nv) / max(len(nu), len(nv))
|
| 21 |
+
|
| 22 |
+
|
| 23 |
+
def cc_min(nu, nv):
|
| 24 |
+
return len(nu & nv) / min(len(nu), len(nv))
|
| 25 |
+
|
| 26 |
+
|
| 27 |
+
modes = {"dot": cc_dot, "min": cc_min, "max": cc_max}
|
| 28 |
+
|
| 29 |
+
|
| 30 |
+
@nx._dispatchable
|
| 31 |
+
def latapy_clustering(G, nodes=None, mode="dot"):
|
| 32 |
+
r"""Compute a bipartite clustering coefficient for nodes.
|
| 33 |
+
|
| 34 |
+
The bipartite clustering coefficient is a measure of local density
|
| 35 |
+
of connections defined as [1]_:
|
| 36 |
+
|
| 37 |
+
.. math::
|
| 38 |
+
|
| 39 |
+
c_u = \frac{\sum_{v \in N(N(u))} c_{uv} }{|N(N(u))|}
|
| 40 |
+
|
| 41 |
+
where `N(N(u))` are the second order neighbors of `u` in `G` excluding `u`,
|
| 42 |
+
and `c_{uv}` is the pairwise clustering coefficient between nodes
|
| 43 |
+
`u` and `v`.
|
| 44 |
+
|
| 45 |
+
The mode selects the function for `c_{uv}` which can be:
|
| 46 |
+
|
| 47 |
+
`dot`:
|
| 48 |
+
|
| 49 |
+
.. math::
|
| 50 |
+
|
| 51 |
+
c_{uv}=\frac{|N(u)\cap N(v)|}{|N(u) \cup N(v)|}
|
| 52 |
+
|
| 53 |
+
`min`:
|
| 54 |
+
|
| 55 |
+
.. math::
|
| 56 |
+
|
| 57 |
+
c_{uv}=\frac{|N(u)\cap N(v)|}{min(|N(u)|,|N(v)|)}
|
| 58 |
+
|
| 59 |
+
`max`:
|
| 60 |
+
|
| 61 |
+
.. math::
|
| 62 |
+
|
| 63 |
+
c_{uv}=\frac{|N(u)\cap N(v)|}{max(|N(u)|,|N(v)|)}
|
| 64 |
+
|
| 65 |
+
|
| 66 |
+
Parameters
|
| 67 |
+
----------
|
| 68 |
+
G : graph
|
| 69 |
+
A bipartite graph
|
| 70 |
+
|
| 71 |
+
nodes : list or iterable (optional)
|
| 72 |
+
Compute bipartite clustering for these nodes. The default
|
| 73 |
+
is all nodes in G.
|
| 74 |
+
|
| 75 |
+
mode : string
|
| 76 |
+
The pairwise bipartite clustering method to be used in the computation.
|
| 77 |
+
It must be "dot", "max", or "min".
|
| 78 |
+
|
| 79 |
+
Returns
|
| 80 |
+
-------
|
| 81 |
+
clustering : dictionary
|
| 82 |
+
A dictionary keyed by node with the clustering coefficient value.
|
| 83 |
+
|
| 84 |
+
|
| 85 |
+
Examples
|
| 86 |
+
--------
|
| 87 |
+
>>> from networkx.algorithms import bipartite
|
| 88 |
+
>>> G = nx.path_graph(4) # path graphs are bipartite
|
| 89 |
+
>>> c = bipartite.clustering(G)
|
| 90 |
+
>>> c[0]
|
| 91 |
+
0.5
|
| 92 |
+
>>> c = bipartite.clustering(G, mode="min")
|
| 93 |
+
>>> c[0]
|
| 94 |
+
1.0
|
| 95 |
+
|
| 96 |
+
See Also
|
| 97 |
+
--------
|
| 98 |
+
robins_alexander_clustering
|
| 99 |
+
average_clustering
|
| 100 |
+
networkx.algorithms.cluster.square_clustering
|
| 101 |
+
|
| 102 |
+
References
|
| 103 |
+
----------
|
| 104 |
+
.. [1] Latapy, Matthieu, Clémence Magnien, and Nathalie Del Vecchio (2008).
|
| 105 |
+
Basic notions for the analysis of large two-mode networks.
|
| 106 |
+
Social Networks 30(1), 31--48.
|
| 107 |
+
"""
|
| 108 |
+
if not nx.algorithms.bipartite.is_bipartite(G):
|
| 109 |
+
raise nx.NetworkXError("Graph is not bipartite")
|
| 110 |
+
|
| 111 |
+
try:
|
| 112 |
+
cc_func = modes[mode]
|
| 113 |
+
except KeyError as err:
|
| 114 |
+
raise nx.NetworkXError(
|
| 115 |
+
"Mode for bipartite clustering must be: dot, min or max"
|
| 116 |
+
) from err
|
| 117 |
+
|
| 118 |
+
if nodes is None:
|
| 119 |
+
nodes = G
|
| 120 |
+
ccs = {}
|
| 121 |
+
for v in nodes:
|
| 122 |
+
cc = 0.0
|
| 123 |
+
nbrs2 = {u for nbr in G[v] for u in G[nbr]} - {v}
|
| 124 |
+
for u in nbrs2:
|
| 125 |
+
cc += cc_func(set(G[u]), set(G[v]))
|
| 126 |
+
if cc > 0.0: # len(nbrs2)>0
|
| 127 |
+
cc /= len(nbrs2)
|
| 128 |
+
ccs[v] = cc
|
| 129 |
+
return ccs
|
| 130 |
+
|
| 131 |
+
|
| 132 |
+
clustering = latapy_clustering
|
| 133 |
+
|
| 134 |
+
|
| 135 |
+
@nx._dispatchable(name="bipartite_average_clustering")
|
| 136 |
+
def average_clustering(G, nodes=None, mode="dot"):
|
| 137 |
+
r"""Compute the average bipartite clustering coefficient.
|
| 138 |
+
|
| 139 |
+
A clustering coefficient for the whole graph is the average,
|
| 140 |
+
|
| 141 |
+
.. math::
|
| 142 |
+
|
| 143 |
+
C = \frac{1}{n}\sum_{v \in G} c_v,
|
| 144 |
+
|
| 145 |
+
where `n` is the number of nodes in `G`.
|
| 146 |
+
|
| 147 |
+
Similar measures for the two bipartite sets can be defined [1]_
|
| 148 |
+
|
| 149 |
+
.. math::
|
| 150 |
+
|
| 151 |
+
C_X = \frac{1}{|X|}\sum_{v \in X} c_v,
|
| 152 |
+
|
| 153 |
+
where `X` is a bipartite set of `G`.
|
| 154 |
+
|
| 155 |
+
Parameters
|
| 156 |
+
----------
|
| 157 |
+
G : graph
|
| 158 |
+
a bipartite graph
|
| 159 |
+
|
| 160 |
+
nodes : list or iterable, optional
|
| 161 |
+
A container of nodes to use in computing the average.
|
| 162 |
+
The nodes should be either the entire graph (the default) or one of the
|
| 163 |
+
bipartite sets.
|
| 164 |
+
|
| 165 |
+
mode : string
|
| 166 |
+
The pairwise bipartite clustering method.
|
| 167 |
+
It must be "dot", "max", or "min"
|
| 168 |
+
|
| 169 |
+
Returns
|
| 170 |
+
-------
|
| 171 |
+
clustering : float
|
| 172 |
+
The average bipartite clustering for the given set of nodes or the
|
| 173 |
+
entire graph if no nodes are specified.
|
| 174 |
+
|
| 175 |
+
Examples
|
| 176 |
+
--------
|
| 177 |
+
>>> from networkx.algorithms import bipartite
|
| 178 |
+
>>> G = nx.star_graph(3) # star graphs are bipartite
|
| 179 |
+
>>> bipartite.average_clustering(G)
|
| 180 |
+
0.75
|
| 181 |
+
>>> X, Y = bipartite.sets(G)
|
| 182 |
+
>>> bipartite.average_clustering(G, X)
|
| 183 |
+
0.0
|
| 184 |
+
>>> bipartite.average_clustering(G, Y)
|
| 185 |
+
1.0
|
| 186 |
+
|
| 187 |
+
See Also
|
| 188 |
+
--------
|
| 189 |
+
clustering
|
| 190 |
+
|
| 191 |
+
Notes
|
| 192 |
+
-----
|
| 193 |
+
The container of nodes passed to this function must contain all of the nodes
|
| 194 |
+
in one of the bipartite sets ("top" or "bottom") in order to compute
|
| 195 |
+
the correct average bipartite clustering coefficients.
|
| 196 |
+
See :mod:`bipartite documentation <networkx.algorithms.bipartite>`
|
| 197 |
+
for further details on how bipartite graphs are handled in NetworkX.
|
| 198 |
+
|
| 199 |
+
|
| 200 |
+
References
|
| 201 |
+
----------
|
| 202 |
+
.. [1] Latapy, Matthieu, Clémence Magnien, and Nathalie Del Vecchio (2008).
|
| 203 |
+
Basic notions for the analysis of large two-mode networks.
|
| 204 |
+
Social Networks 30(1), 31--48.
|
| 205 |
+
"""
|
| 206 |
+
if nodes is None:
|
| 207 |
+
nodes = G
|
| 208 |
+
ccs = latapy_clustering(G, nodes=nodes, mode=mode)
|
| 209 |
+
return sum(ccs[v] for v in nodes) / len(nodes)
|
| 210 |
+
|
| 211 |
+
|
| 212 |
+
@nx._dispatchable
|
| 213 |
+
def robins_alexander_clustering(G):
|
| 214 |
+
r"""Compute the bipartite clustering of G.
|
| 215 |
+
|
| 216 |
+
Robins and Alexander [1]_ defined bipartite clustering coefficient as
|
| 217 |
+
four times the number of four cycles `C_4` divided by the number of
|
| 218 |
+
three paths `L_3` in a bipartite graph:
|
| 219 |
+
|
| 220 |
+
.. math::
|
| 221 |
+
|
| 222 |
+
CC_4 = \frac{4 * C_4}{L_3}
|
| 223 |
+
|
| 224 |
+
Parameters
|
| 225 |
+
----------
|
| 226 |
+
G : graph
|
| 227 |
+
a bipartite graph
|
| 228 |
+
|
| 229 |
+
Returns
|
| 230 |
+
-------
|
| 231 |
+
clustering : float
|
| 232 |
+
The Robins and Alexander bipartite clustering for the input graph.
|
| 233 |
+
|
| 234 |
+
Examples
|
| 235 |
+
--------
|
| 236 |
+
>>> from networkx.algorithms import bipartite
|
| 237 |
+
>>> G = nx.davis_southern_women_graph()
|
| 238 |
+
>>> print(round(bipartite.robins_alexander_clustering(G), 3))
|
| 239 |
+
0.468
|
| 240 |
+
|
| 241 |
+
See Also
|
| 242 |
+
--------
|
| 243 |
+
latapy_clustering
|
| 244 |
+
networkx.algorithms.cluster.square_clustering
|
| 245 |
+
|
| 246 |
+
References
|
| 247 |
+
----------
|
| 248 |
+
.. [1] Robins, G. and M. Alexander (2004). Small worlds among interlocking
|
| 249 |
+
directors: Network structure and distance in bipartite graphs.
|
| 250 |
+
Computational & Mathematical Organization Theory 10(1), 69–94.
|
| 251 |
+
|
| 252 |
+
"""
|
| 253 |
+
if G.order() < 4 or G.size() < 3:
|
| 254 |
+
return 0
|
| 255 |
+
L_3 = _threepaths(G)
|
| 256 |
+
if L_3 == 0:
|
| 257 |
+
return 0
|
| 258 |
+
C_4 = _four_cycles(G)
|
| 259 |
+
return (4.0 * C_4) / L_3
|
| 260 |
+
|
| 261 |
+
|
| 262 |
+
def _four_cycles(G):
|
| 263 |
+
# Also see `square_clustering` which counts squares in a similar way
|
| 264 |
+
cycles = 0
|
| 265 |
+
seen = set()
|
| 266 |
+
G_adj = G._adj
|
| 267 |
+
for v in G:
|
| 268 |
+
seen.add(v)
|
| 269 |
+
v_neighbors = set(G_adj[v])
|
| 270 |
+
if len(v_neighbors) < 2:
|
| 271 |
+
# Can't form a square without at least two neighbors
|
| 272 |
+
continue
|
| 273 |
+
two_hop_neighbors = set().union(*(G_adj[u] for u in v_neighbors))
|
| 274 |
+
two_hop_neighbors -= seen
|
| 275 |
+
for x in two_hop_neighbors:
|
| 276 |
+
p2 = len(v_neighbors.intersection(G_adj[x]))
|
| 277 |
+
cycles += p2 * (p2 - 1)
|
| 278 |
+
return cycles / 4
|
| 279 |
+
|
| 280 |
+
|
| 281 |
+
def _threepaths(G):
|
| 282 |
+
paths = 0
|
| 283 |
+
for v in G:
|
| 284 |
+
for u in G[v]:
|
| 285 |
+
for w in set(G[u]) - {v}:
|
| 286 |
+
paths += len(set(G[w]) - {v, u})
|
| 287 |
+
# Divide by two because we count each three path twice
|
| 288 |
+
# one for each possible starting point
|
| 289 |
+
return paths / 2
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/covering.py
ADDED
|
@@ -0,0 +1,57 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions related to graph covers."""
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
from networkx.algorithms.bipartite.matching import hopcroft_karp_matching
|
| 5 |
+
from networkx.algorithms.covering import min_edge_cover as _min_edge_cover
|
| 6 |
+
from networkx.utils import not_implemented_for
|
| 7 |
+
|
| 8 |
+
__all__ = ["min_edge_cover"]
|
| 9 |
+
|
| 10 |
+
|
| 11 |
+
@not_implemented_for("directed")
|
| 12 |
+
@not_implemented_for("multigraph")
|
| 13 |
+
@nx._dispatchable(name="bipartite_min_edge_cover")
|
| 14 |
+
def min_edge_cover(G, matching_algorithm=None):
|
| 15 |
+
"""Returns a set of edges which constitutes
|
| 16 |
+
the minimum edge cover of the graph.
|
| 17 |
+
|
| 18 |
+
The smallest edge cover can be found in polynomial time by finding
|
| 19 |
+
a maximum matching and extending it greedily so that all nodes
|
| 20 |
+
are covered.
|
| 21 |
+
|
| 22 |
+
Parameters
|
| 23 |
+
----------
|
| 24 |
+
G : NetworkX graph
|
| 25 |
+
An undirected bipartite graph.
|
| 26 |
+
|
| 27 |
+
matching_algorithm : function
|
| 28 |
+
A function that returns a maximum cardinality matching in a
|
| 29 |
+
given bipartite graph. The function must take one input, the
|
| 30 |
+
graph ``G``, and return a dictionary mapping each node to its
|
| 31 |
+
mate. If not specified,
|
| 32 |
+
:func:`~networkx.algorithms.bipartite.matching.hopcroft_karp_matching`
|
| 33 |
+
will be used. Other possibilities include
|
| 34 |
+
:func:`~networkx.algorithms.bipartite.matching.eppstein_matching`,
|
| 35 |
+
|
| 36 |
+
Returns
|
| 37 |
+
-------
|
| 38 |
+
set
|
| 39 |
+
A set of the edges in a minimum edge cover of the graph, given as
|
| 40 |
+
pairs of nodes. It contains both the edges `(u, v)` and `(v, u)`
|
| 41 |
+
for given nodes `u` and `v` among the edges of minimum edge cover.
|
| 42 |
+
|
| 43 |
+
Notes
|
| 44 |
+
-----
|
| 45 |
+
An edge cover of a graph is a set of edges such that every node of
|
| 46 |
+
the graph is incident to at least one edge of the set.
|
| 47 |
+
A minimum edge cover is an edge covering of smallest cardinality.
|
| 48 |
+
|
| 49 |
+
Due to its implementation, the worst-case running time of this algorithm
|
| 50 |
+
is bounded by the worst-case running time of the function
|
| 51 |
+
``matching_algorithm``.
|
| 52 |
+
"""
|
| 53 |
+
if G.order() == 0: # Special case for the empty graph
|
| 54 |
+
return set()
|
| 55 |
+
if matching_algorithm is None:
|
| 56 |
+
matching_algorithm = hopcroft_karp_matching
|
| 57 |
+
return _min_edge_cover(G, matching_algorithm=matching_algorithm)
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/edgelist.py
ADDED
|
@@ -0,0 +1,360 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
********************
|
| 3 |
+
Bipartite Edge Lists
|
| 4 |
+
********************
|
| 5 |
+
Read and write NetworkX graphs as bipartite edge lists.
|
| 6 |
+
|
| 7 |
+
Format
|
| 8 |
+
------
|
| 9 |
+
You can read or write three formats of edge lists with these functions.
|
| 10 |
+
|
| 11 |
+
Node pairs with no data::
|
| 12 |
+
|
| 13 |
+
1 2
|
| 14 |
+
|
| 15 |
+
Python dictionary as data::
|
| 16 |
+
|
| 17 |
+
1 2 {'weight':7, 'color':'green'}
|
| 18 |
+
|
| 19 |
+
Arbitrary data::
|
| 20 |
+
|
| 21 |
+
1 2 7 green
|
| 22 |
+
|
| 23 |
+
For each edge (u, v) the node u is assigned to part 0 and the node v to part 1.
|
| 24 |
+
"""
|
| 25 |
+
|
| 26 |
+
__all__ = ["generate_edgelist", "write_edgelist", "parse_edgelist", "read_edgelist"]
|
| 27 |
+
|
| 28 |
+
import networkx as nx
|
| 29 |
+
from networkx.utils import not_implemented_for, open_file
|
| 30 |
+
|
| 31 |
+
|
| 32 |
+
@open_file(1, mode="wb")
|
| 33 |
+
def write_edgelist(G, path, comments="#", delimiter=" ", data=True, encoding="utf-8"):
|
| 34 |
+
"""Write a bipartite graph as a list of edges.
|
| 35 |
+
|
| 36 |
+
Parameters
|
| 37 |
+
----------
|
| 38 |
+
G : Graph
|
| 39 |
+
A NetworkX bipartite graph
|
| 40 |
+
path : file or string
|
| 41 |
+
File or filename to write. If a file is provided, it must be
|
| 42 |
+
opened in 'wb' mode. Filenames ending in .gz or .bz2 will be compressed.
|
| 43 |
+
comments : string, optional
|
| 44 |
+
The character used to indicate the start of a comment
|
| 45 |
+
delimiter : string, optional
|
| 46 |
+
The string used to separate values. The default is whitespace.
|
| 47 |
+
data : bool or list, optional
|
| 48 |
+
If False write no edge data.
|
| 49 |
+
If True write a string representation of the edge data dictionary..
|
| 50 |
+
If a list (or other iterable) is provided, write the keys specified
|
| 51 |
+
in the list.
|
| 52 |
+
encoding: string, optional
|
| 53 |
+
Specify which encoding to use when writing file.
|
| 54 |
+
|
| 55 |
+
Examples
|
| 56 |
+
--------
|
| 57 |
+
>>> G = nx.path_graph(4)
|
| 58 |
+
>>> G.add_nodes_from([0, 2], bipartite=0)
|
| 59 |
+
>>> G.add_nodes_from([1, 3], bipartite=1)
|
| 60 |
+
>>> nx.write_edgelist(G, "test.edgelist")
|
| 61 |
+
>>> fh = open("test.edgelist_open", "wb")
|
| 62 |
+
>>> nx.write_edgelist(G, fh)
|
| 63 |
+
>>> nx.write_edgelist(G, "test.edgelist.gz")
|
| 64 |
+
>>> nx.write_edgelist(G, "test.edgelist_nodata.gz", data=False)
|
| 65 |
+
|
| 66 |
+
>>> G = nx.Graph()
|
| 67 |
+
>>> G.add_edge(1, 2, weight=7, color="red")
|
| 68 |
+
>>> nx.write_edgelist(G, "test.edgelist_bigger_nodata", data=False)
|
| 69 |
+
>>> nx.write_edgelist(G, "test.edgelist_color", data=["color"])
|
| 70 |
+
>>> nx.write_edgelist(G, "test.edgelist_color_weight", data=["color", "weight"])
|
| 71 |
+
|
| 72 |
+
See Also
|
| 73 |
+
--------
|
| 74 |
+
write_edgelist
|
| 75 |
+
generate_edgelist
|
| 76 |
+
"""
|
| 77 |
+
for line in generate_edgelist(G, delimiter, data):
|
| 78 |
+
line += "\n"
|
| 79 |
+
path.write(line.encode(encoding))
|
| 80 |
+
|
| 81 |
+
|
| 82 |
+
@not_implemented_for("directed")
|
| 83 |
+
def generate_edgelist(G, delimiter=" ", data=True):
|
| 84 |
+
"""Generate a single line of the bipartite graph G in edge list format.
|
| 85 |
+
|
| 86 |
+
Parameters
|
| 87 |
+
----------
|
| 88 |
+
G : NetworkX graph
|
| 89 |
+
The graph is assumed to have node attribute `part` set to 0,1 representing
|
| 90 |
+
the two graph parts
|
| 91 |
+
|
| 92 |
+
delimiter : string, optional
|
| 93 |
+
Separator for node labels
|
| 94 |
+
|
| 95 |
+
data : bool or list of keys
|
| 96 |
+
If False generate no edge data. If True use a dictionary
|
| 97 |
+
representation of edge data. If a list of keys use a list of data
|
| 98 |
+
values corresponding to the keys.
|
| 99 |
+
|
| 100 |
+
Returns
|
| 101 |
+
-------
|
| 102 |
+
lines : string
|
| 103 |
+
Lines of data in adjlist format.
|
| 104 |
+
|
| 105 |
+
Examples
|
| 106 |
+
--------
|
| 107 |
+
>>> from networkx.algorithms import bipartite
|
| 108 |
+
>>> G = nx.path_graph(4)
|
| 109 |
+
>>> G.add_nodes_from([0, 2], bipartite=0)
|
| 110 |
+
>>> G.add_nodes_from([1, 3], bipartite=1)
|
| 111 |
+
>>> G[1][2]["weight"] = 3
|
| 112 |
+
>>> G[2][3]["capacity"] = 12
|
| 113 |
+
>>> for line in bipartite.generate_edgelist(G, data=False):
|
| 114 |
+
... print(line)
|
| 115 |
+
0 1
|
| 116 |
+
2 1
|
| 117 |
+
2 3
|
| 118 |
+
|
| 119 |
+
>>> for line in bipartite.generate_edgelist(G):
|
| 120 |
+
... print(line)
|
| 121 |
+
0 1 {}
|
| 122 |
+
2 1 {'weight': 3}
|
| 123 |
+
2 3 {'capacity': 12}
|
| 124 |
+
|
| 125 |
+
>>> for line in bipartite.generate_edgelist(G, data=["weight"]):
|
| 126 |
+
... print(line)
|
| 127 |
+
0 1
|
| 128 |
+
2 1 3
|
| 129 |
+
2 3
|
| 130 |
+
"""
|
| 131 |
+
try:
|
| 132 |
+
part0 = [n for n, d in G.nodes.items() if d["bipartite"] == 0]
|
| 133 |
+
except BaseException as err:
|
| 134 |
+
raise AttributeError("Missing node attribute `bipartite`") from err
|
| 135 |
+
if data is True or data is False:
|
| 136 |
+
for n in part0:
|
| 137 |
+
for edge in G.edges(n, data=data):
|
| 138 |
+
yield delimiter.join(map(str, edge))
|
| 139 |
+
else:
|
| 140 |
+
for n in part0:
|
| 141 |
+
for u, v, d in G.edges(n, data=True):
|
| 142 |
+
edge = [u, v]
|
| 143 |
+
try:
|
| 144 |
+
edge.extend(d[k] for k in data)
|
| 145 |
+
except KeyError:
|
| 146 |
+
pass # missing data for this edge, should warn?
|
| 147 |
+
yield delimiter.join(map(str, edge))
|
| 148 |
+
|
| 149 |
+
|
| 150 |
+
@nx._dispatchable(name="bipartite_parse_edgelist", graphs=None, returns_graph=True)
|
| 151 |
+
def parse_edgelist(
|
| 152 |
+
lines, comments="#", delimiter=None, create_using=None, nodetype=None, data=True
|
| 153 |
+
):
|
| 154 |
+
"""Parse lines of an edge list representation of a bipartite graph.
|
| 155 |
+
|
| 156 |
+
Parameters
|
| 157 |
+
----------
|
| 158 |
+
lines : list or iterator of strings
|
| 159 |
+
Input data in edgelist format
|
| 160 |
+
comments : string, optional
|
| 161 |
+
Marker for comment lines
|
| 162 |
+
delimiter : string, optional
|
| 163 |
+
Separator for node labels
|
| 164 |
+
create_using: NetworkX graph container, optional
|
| 165 |
+
Use given NetworkX graph for holding nodes or edges.
|
| 166 |
+
nodetype : Python type, optional
|
| 167 |
+
Convert nodes to this type.
|
| 168 |
+
data : bool or list of (label,type) tuples
|
| 169 |
+
If False generate no edge data or if True use a dictionary
|
| 170 |
+
representation of edge data or a list tuples specifying dictionary
|
| 171 |
+
key names and types for edge data.
|
| 172 |
+
|
| 173 |
+
Returns
|
| 174 |
+
-------
|
| 175 |
+
G: NetworkX Graph
|
| 176 |
+
The bipartite graph corresponding to lines
|
| 177 |
+
|
| 178 |
+
Examples
|
| 179 |
+
--------
|
| 180 |
+
Edgelist with no data:
|
| 181 |
+
|
| 182 |
+
>>> from networkx.algorithms import bipartite
|
| 183 |
+
>>> lines = ["1 2", "2 3", "3 4"]
|
| 184 |
+
>>> G = bipartite.parse_edgelist(lines, nodetype=int)
|
| 185 |
+
>>> sorted(G.nodes())
|
| 186 |
+
[1, 2, 3, 4]
|
| 187 |
+
>>> sorted(G.nodes(data=True))
|
| 188 |
+
[(1, {'bipartite': 0}), (2, {'bipartite': 0}), (3, {'bipartite': 0}), (4, {'bipartite': 1})]
|
| 189 |
+
>>> sorted(G.edges())
|
| 190 |
+
[(1, 2), (2, 3), (3, 4)]
|
| 191 |
+
|
| 192 |
+
Edgelist with data in Python dictionary representation:
|
| 193 |
+
|
| 194 |
+
>>> lines = ["1 2 {'weight':3}", "2 3 {'weight':27}", "3 4 {'weight':3.0}"]
|
| 195 |
+
>>> G = bipartite.parse_edgelist(lines, nodetype=int)
|
| 196 |
+
>>> sorted(G.nodes())
|
| 197 |
+
[1, 2, 3, 4]
|
| 198 |
+
>>> sorted(G.edges(data=True))
|
| 199 |
+
[(1, 2, {'weight': 3}), (2, 3, {'weight': 27}), (3, 4, {'weight': 3.0})]
|
| 200 |
+
|
| 201 |
+
Edgelist with data in a list:
|
| 202 |
+
|
| 203 |
+
>>> lines = ["1 2 3", "2 3 27", "3 4 3.0"]
|
| 204 |
+
>>> G = bipartite.parse_edgelist(lines, nodetype=int, data=(("weight", float),))
|
| 205 |
+
>>> sorted(G.nodes())
|
| 206 |
+
[1, 2, 3, 4]
|
| 207 |
+
>>> sorted(G.edges(data=True))
|
| 208 |
+
[(1, 2, {'weight': 3.0}), (2, 3, {'weight': 27.0}), (3, 4, {'weight': 3.0})]
|
| 209 |
+
|
| 210 |
+
See Also
|
| 211 |
+
--------
|
| 212 |
+
"""
|
| 213 |
+
from ast import literal_eval
|
| 214 |
+
|
| 215 |
+
G = nx.empty_graph(0, create_using)
|
| 216 |
+
for line in lines:
|
| 217 |
+
p = line.find(comments)
|
| 218 |
+
if p >= 0:
|
| 219 |
+
line = line[:p]
|
| 220 |
+
if not len(line):
|
| 221 |
+
continue
|
| 222 |
+
# split line, should have 2 or more
|
| 223 |
+
s = line.rstrip("\n").split(delimiter)
|
| 224 |
+
if len(s) < 2:
|
| 225 |
+
continue
|
| 226 |
+
u = s.pop(0)
|
| 227 |
+
v = s.pop(0)
|
| 228 |
+
d = s
|
| 229 |
+
if nodetype is not None:
|
| 230 |
+
try:
|
| 231 |
+
u = nodetype(u)
|
| 232 |
+
v = nodetype(v)
|
| 233 |
+
except BaseException as err:
|
| 234 |
+
raise TypeError(
|
| 235 |
+
f"Failed to convert nodes {u},{v} to type {nodetype}."
|
| 236 |
+
) from err
|
| 237 |
+
|
| 238 |
+
if len(d) == 0 or data is False:
|
| 239 |
+
# no data or data type specified
|
| 240 |
+
edgedata = {}
|
| 241 |
+
elif data is True:
|
| 242 |
+
# no edge types specified
|
| 243 |
+
try: # try to evaluate as dictionary
|
| 244 |
+
edgedata = dict(literal_eval(" ".join(d)))
|
| 245 |
+
except BaseException as err:
|
| 246 |
+
raise TypeError(
|
| 247 |
+
f"Failed to convert edge data ({d}) to dictionary."
|
| 248 |
+
) from err
|
| 249 |
+
else:
|
| 250 |
+
# convert edge data to dictionary with specified keys and type
|
| 251 |
+
if len(d) != len(data):
|
| 252 |
+
raise IndexError(
|
| 253 |
+
f"Edge data {d} and data_keys {data} are not the same length"
|
| 254 |
+
)
|
| 255 |
+
edgedata = {}
|
| 256 |
+
for (edge_key, edge_type), edge_value in zip(data, d):
|
| 257 |
+
try:
|
| 258 |
+
edge_value = edge_type(edge_value)
|
| 259 |
+
except BaseException as err:
|
| 260 |
+
raise TypeError(
|
| 261 |
+
f"Failed to convert {edge_key} data "
|
| 262 |
+
f"{edge_value} to type {edge_type}."
|
| 263 |
+
) from err
|
| 264 |
+
edgedata.update({edge_key: edge_value})
|
| 265 |
+
G.add_node(u, bipartite=0)
|
| 266 |
+
G.add_node(v, bipartite=1)
|
| 267 |
+
G.add_edge(u, v, **edgedata)
|
| 268 |
+
return G
|
| 269 |
+
|
| 270 |
+
|
| 271 |
+
@open_file(0, mode="rb")
|
| 272 |
+
@nx._dispatchable(name="bipartite_read_edgelist", graphs=None, returns_graph=True)
|
| 273 |
+
def read_edgelist(
|
| 274 |
+
path,
|
| 275 |
+
comments="#",
|
| 276 |
+
delimiter=None,
|
| 277 |
+
create_using=None,
|
| 278 |
+
nodetype=None,
|
| 279 |
+
data=True,
|
| 280 |
+
edgetype=None,
|
| 281 |
+
encoding="utf-8",
|
| 282 |
+
):
|
| 283 |
+
"""Read a bipartite graph from a list of edges.
|
| 284 |
+
|
| 285 |
+
Parameters
|
| 286 |
+
----------
|
| 287 |
+
path : file or string
|
| 288 |
+
File or filename to read. If a file is provided, it must be
|
| 289 |
+
opened in 'rb' mode.
|
| 290 |
+
Filenames ending in .gz or .bz2 will be decompressed.
|
| 291 |
+
comments : string, optional
|
| 292 |
+
The character used to indicate the start of a comment.
|
| 293 |
+
delimiter : string, optional
|
| 294 |
+
The string used to separate values. The default is whitespace.
|
| 295 |
+
create_using : Graph container, optional,
|
| 296 |
+
Use specified container to build graph. The default is networkx.Graph,
|
| 297 |
+
an undirected graph.
|
| 298 |
+
nodetype : int, float, str, Python type, optional
|
| 299 |
+
Convert node data from strings to specified type
|
| 300 |
+
data : bool or list of (label,type) tuples
|
| 301 |
+
Tuples specifying dictionary key names and types for edge data
|
| 302 |
+
edgetype : int, float, str, Python type, optional OBSOLETE
|
| 303 |
+
Convert edge data from strings to specified type and use as 'weight'
|
| 304 |
+
encoding: string, optional
|
| 305 |
+
Specify which encoding to use when reading file.
|
| 306 |
+
|
| 307 |
+
Returns
|
| 308 |
+
-------
|
| 309 |
+
G : graph
|
| 310 |
+
A networkx Graph or other type specified with create_using
|
| 311 |
+
|
| 312 |
+
Examples
|
| 313 |
+
--------
|
| 314 |
+
>>> from networkx.algorithms import bipartite
|
| 315 |
+
>>> G = nx.path_graph(4)
|
| 316 |
+
>>> G.add_nodes_from([0, 2], bipartite=0)
|
| 317 |
+
>>> G.add_nodes_from([1, 3], bipartite=1)
|
| 318 |
+
>>> bipartite.write_edgelist(G, "test.edgelist")
|
| 319 |
+
>>> G = bipartite.read_edgelist("test.edgelist")
|
| 320 |
+
|
| 321 |
+
>>> fh = open("test.edgelist", "rb")
|
| 322 |
+
>>> G = bipartite.read_edgelist(fh)
|
| 323 |
+
>>> fh.close()
|
| 324 |
+
|
| 325 |
+
>>> G = bipartite.read_edgelist("test.edgelist", nodetype=int)
|
| 326 |
+
|
| 327 |
+
Edgelist with data in a list:
|
| 328 |
+
|
| 329 |
+
>>> textline = "1 2 3"
|
| 330 |
+
>>> fh = open("test.edgelist", "w")
|
| 331 |
+
>>> d = fh.write(textline)
|
| 332 |
+
>>> fh.close()
|
| 333 |
+
>>> G = bipartite.read_edgelist(
|
| 334 |
+
... "test.edgelist", nodetype=int, data=(("weight", float),)
|
| 335 |
+
... )
|
| 336 |
+
>>> list(G)
|
| 337 |
+
[1, 2]
|
| 338 |
+
>>> list(G.edges(data=True))
|
| 339 |
+
[(1, 2, {'weight': 3.0})]
|
| 340 |
+
|
| 341 |
+
See parse_edgelist() for more examples of formatting.
|
| 342 |
+
|
| 343 |
+
See Also
|
| 344 |
+
--------
|
| 345 |
+
parse_edgelist
|
| 346 |
+
|
| 347 |
+
Notes
|
| 348 |
+
-----
|
| 349 |
+
Since nodes must be hashable, the function nodetype must return hashable
|
| 350 |
+
types (e.g. int, float, str, frozenset - or tuples of those, etc.)
|
| 351 |
+
"""
|
| 352 |
+
lines = (line.decode(encoding) for line in path)
|
| 353 |
+
return parse_edgelist(
|
| 354 |
+
lines,
|
| 355 |
+
comments=comments,
|
| 356 |
+
delimiter=delimiter,
|
| 357 |
+
create_using=create_using,
|
| 358 |
+
nodetype=nodetype,
|
| 359 |
+
data=data,
|
| 360 |
+
)
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/extendability.py
ADDED
|
@@ -0,0 +1,105 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Provides a function for computing the extendability of a graph which is
|
| 2 |
+
undirected, simple, connected and bipartite and contains at least one perfect matching."""
|
| 3 |
+
|
| 4 |
+
import networkx as nx
|
| 5 |
+
from networkx.utils import not_implemented_for
|
| 6 |
+
|
| 7 |
+
__all__ = ["maximal_extendability"]
|
| 8 |
+
|
| 9 |
+
|
| 10 |
+
@not_implemented_for("directed")
|
| 11 |
+
@not_implemented_for("multigraph")
|
| 12 |
+
@nx._dispatchable
|
| 13 |
+
def maximal_extendability(G):
|
| 14 |
+
"""Computes the extendability of a graph.
|
| 15 |
+
|
| 16 |
+
The extendability of a graph is defined as the maximum $k$ for which `G`
|
| 17 |
+
is $k$-extendable. Graph `G` is $k$-extendable if and only if `G` has a
|
| 18 |
+
perfect matching and every set of $k$ independent edges can be extended
|
| 19 |
+
to a perfect matching in `G`.
|
| 20 |
+
|
| 21 |
+
Parameters
|
| 22 |
+
----------
|
| 23 |
+
G : NetworkX Graph
|
| 24 |
+
A fully-connected bipartite graph without self-loops
|
| 25 |
+
|
| 26 |
+
Returns
|
| 27 |
+
-------
|
| 28 |
+
extendability : int
|
| 29 |
+
|
| 30 |
+
Raises
|
| 31 |
+
------
|
| 32 |
+
NetworkXError
|
| 33 |
+
If the graph `G` is disconnected.
|
| 34 |
+
If the graph `G` is not bipartite.
|
| 35 |
+
If the graph `G` does not contain a perfect matching.
|
| 36 |
+
If the residual graph of `G` is not strongly connected.
|
| 37 |
+
|
| 38 |
+
Notes
|
| 39 |
+
-----
|
| 40 |
+
Definition:
|
| 41 |
+
Let `G` be a simple, connected, undirected and bipartite graph with a perfect
|
| 42 |
+
matching M and bipartition (U,V). The residual graph of `G`, denoted by $G_M$,
|
| 43 |
+
is the graph obtained from G by directing the edges of M from V to U and the
|
| 44 |
+
edges that do not belong to M from U to V.
|
| 45 |
+
|
| 46 |
+
Lemma [1]_ :
|
| 47 |
+
Let M be a perfect matching of `G`. `G` is $k$-extendable if and only if its residual
|
| 48 |
+
graph $G_M$ is strongly connected and there are $k$ vertex-disjoint directed
|
| 49 |
+
paths between every vertex of U and every vertex of V.
|
| 50 |
+
|
| 51 |
+
Assuming that input graph `G` is undirected, simple, connected, bipartite and contains
|
| 52 |
+
a perfect matching M, this function constructs the residual graph $G_M$ of G and
|
| 53 |
+
returns the minimum value among the maximum vertex-disjoint directed paths between
|
| 54 |
+
every vertex of U and every vertex of V in $G_M$. By combining the definitions
|
| 55 |
+
and the lemma, this value represents the extendability of the graph `G`.
|
| 56 |
+
|
| 57 |
+
Time complexity O($n^3$ $m^2$)) where $n$ is the number of vertices
|
| 58 |
+
and $m$ is the number of edges.
|
| 59 |
+
|
| 60 |
+
References
|
| 61 |
+
----------
|
| 62 |
+
.. [1] "A polynomial algorithm for the extendability problem in bipartite graphs",
|
| 63 |
+
J. Lakhal, L. Litzler, Information Processing Letters, 1998.
|
| 64 |
+
.. [2] "On n-extendible graphs", M. D. Plummer, Discrete Mathematics, 31:201–210, 1980
|
| 65 |
+
https://doi.org/10.1016/0012-365X(80)90037-0
|
| 66 |
+
|
| 67 |
+
"""
|
| 68 |
+
if not nx.is_connected(G):
|
| 69 |
+
raise nx.NetworkXError("Graph G is not connected")
|
| 70 |
+
|
| 71 |
+
if not nx.bipartite.is_bipartite(G):
|
| 72 |
+
raise nx.NetworkXError("Graph G is not bipartite")
|
| 73 |
+
|
| 74 |
+
U, V = nx.bipartite.sets(G)
|
| 75 |
+
|
| 76 |
+
maximum_matching = nx.bipartite.hopcroft_karp_matching(G)
|
| 77 |
+
|
| 78 |
+
if not nx.is_perfect_matching(G, maximum_matching):
|
| 79 |
+
raise nx.NetworkXError("Graph G does not contain a perfect matching")
|
| 80 |
+
|
| 81 |
+
# list of edges in perfect matching, directed from V to U
|
| 82 |
+
pm = [(node, maximum_matching[node]) for node in V & maximum_matching.keys()]
|
| 83 |
+
|
| 84 |
+
# Direct all the edges of G, from V to U if in matching, else from U to V
|
| 85 |
+
directed_edges = [
|
| 86 |
+
(x, y) if (x in V and (x, y) in pm) or (x in U and (y, x) not in pm) else (y, x)
|
| 87 |
+
for x, y in G.edges
|
| 88 |
+
]
|
| 89 |
+
|
| 90 |
+
# Construct the residual graph of G
|
| 91 |
+
residual_G = nx.DiGraph()
|
| 92 |
+
residual_G.add_nodes_from(G)
|
| 93 |
+
residual_G.add_edges_from(directed_edges)
|
| 94 |
+
|
| 95 |
+
if not nx.is_strongly_connected(residual_G):
|
| 96 |
+
raise nx.NetworkXError("The residual graph of G is not strongly connected")
|
| 97 |
+
|
| 98 |
+
# For node-pairs between V & U, keep min of max number of node-disjoint paths
|
| 99 |
+
# Variable $k$ stands for the extendability of graph G
|
| 100 |
+
k = float("inf")
|
| 101 |
+
for u in U:
|
| 102 |
+
for v in V:
|
| 103 |
+
num_paths = sum(1 for _ in nx.node_disjoint_paths(residual_G, u, v))
|
| 104 |
+
k = k if k < num_paths else num_paths
|
| 105 |
+
return k
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bipartite/generators.py
ADDED
|
@@ -0,0 +1,603 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
Generators and functions for bipartite graphs.
|
| 3 |
+
"""
|
| 4 |
+
|
| 5 |
+
import math
|
| 6 |
+
import numbers
|
| 7 |
+
from functools import reduce
|
| 8 |
+
|
| 9 |
+
import networkx as nx
|
| 10 |
+
from networkx.utils import nodes_or_number, py_random_state
|
| 11 |
+
|
| 12 |
+
__all__ = [
|
| 13 |
+
"configuration_model",
|
| 14 |
+
"havel_hakimi_graph",
|
| 15 |
+
"reverse_havel_hakimi_graph",
|
| 16 |
+
"alternating_havel_hakimi_graph",
|
| 17 |
+
"preferential_attachment_graph",
|
| 18 |
+
"random_graph",
|
| 19 |
+
"gnmk_random_graph",
|
| 20 |
+
"complete_bipartite_graph",
|
| 21 |
+
]
|
| 22 |
+
|
| 23 |
+
|
| 24 |
+
@nx._dispatchable(graphs=None, returns_graph=True)
|
| 25 |
+
@nodes_or_number([0, 1])
|
| 26 |
+
def complete_bipartite_graph(n1, n2, create_using=None):
|
| 27 |
+
"""Returns the complete bipartite graph `K_{n_1,n_2}`.
|
| 28 |
+
|
| 29 |
+
The graph is composed of two partitions with nodes 0 to (n1 - 1)
|
| 30 |
+
in the first and nodes n1 to (n1 + n2 - 1) in the second.
|
| 31 |
+
Each node in the first is connected to each node in the second.
|
| 32 |
+
|
| 33 |
+
Parameters
|
| 34 |
+
----------
|
| 35 |
+
n1, n2 : integer or iterable container of nodes
|
| 36 |
+
If integers, nodes are from `range(n1)` and `range(n1, n1 + n2)`.
|
| 37 |
+
If a container, the elements are the nodes.
|
| 38 |
+
create_using : NetworkX graph instance, (default: nx.Graph)
|
| 39 |
+
Return graph of this type.
|
| 40 |
+
|
| 41 |
+
Notes
|
| 42 |
+
-----
|
| 43 |
+
Nodes are the integers 0 to `n1 + n2 - 1` unless either n1 or n2 are
|
| 44 |
+
containers of nodes. If only one of n1 or n2 are integers, that
|
| 45 |
+
integer is replaced by `range` of that integer.
|
| 46 |
+
|
| 47 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 48 |
+
to indicate which bipartite set the node belongs to.
|
| 49 |
+
|
| 50 |
+
This function is not imported in the main namespace.
|
| 51 |
+
To use it use nx.bipartite.complete_bipartite_graph
|
| 52 |
+
"""
|
| 53 |
+
G = nx.empty_graph(0, create_using)
|
| 54 |
+
if G.is_directed():
|
| 55 |
+
raise nx.NetworkXError("Directed Graph not supported")
|
| 56 |
+
|
| 57 |
+
n1, top = n1
|
| 58 |
+
n2, bottom = n2
|
| 59 |
+
if isinstance(n1, numbers.Integral) and isinstance(n2, numbers.Integral):
|
| 60 |
+
bottom = [n1 + i for i in bottom]
|
| 61 |
+
G.add_nodes_from(top, bipartite=0)
|
| 62 |
+
G.add_nodes_from(bottom, bipartite=1)
|
| 63 |
+
if len(G) != len(top) + len(bottom):
|
| 64 |
+
raise nx.NetworkXError("Inputs n1 and n2 must contain distinct nodes")
|
| 65 |
+
G.add_edges_from((u, v) for u in top for v in bottom)
|
| 66 |
+
G.graph["name"] = f"complete_bipartite_graph({len(top)}, {len(bottom)})"
|
| 67 |
+
return G
|
| 68 |
+
|
| 69 |
+
|
| 70 |
+
@py_random_state(3)
|
| 71 |
+
@nx._dispatchable(name="bipartite_configuration_model", graphs=None, returns_graph=True)
|
| 72 |
+
def configuration_model(aseq, bseq, create_using=None, seed=None):
|
| 73 |
+
"""Returns a random bipartite graph from two given degree sequences.
|
| 74 |
+
|
| 75 |
+
Parameters
|
| 76 |
+
----------
|
| 77 |
+
aseq : list
|
| 78 |
+
Degree sequence for node set A.
|
| 79 |
+
bseq : list
|
| 80 |
+
Degree sequence for node set B.
|
| 81 |
+
create_using : NetworkX graph instance, optional
|
| 82 |
+
Return graph of this type.
|
| 83 |
+
seed : integer, random_state, or None (default)
|
| 84 |
+
Indicator of random number generation state.
|
| 85 |
+
See :ref:`Randomness<randomness>`.
|
| 86 |
+
|
| 87 |
+
The graph is composed of two partitions. Set A has nodes 0 to
|
| 88 |
+
(len(aseq) - 1) and set B has nodes len(aseq) to (len(bseq) - 1).
|
| 89 |
+
Nodes from set A are connected to nodes in set B by choosing
|
| 90 |
+
randomly from the possible free stubs, one in A and one in B.
|
| 91 |
+
|
| 92 |
+
Notes
|
| 93 |
+
-----
|
| 94 |
+
The sum of the two sequences must be equal: sum(aseq)=sum(bseq)
|
| 95 |
+
If no graph type is specified use MultiGraph with parallel edges.
|
| 96 |
+
If you want a graph with no parallel edges use create_using=Graph()
|
| 97 |
+
but then the resulting degree sequences might not be exact.
|
| 98 |
+
|
| 99 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 100 |
+
to indicate which bipartite set the node belongs to.
|
| 101 |
+
|
| 102 |
+
This function is not imported in the main namespace.
|
| 103 |
+
To use it use nx.bipartite.configuration_model
|
| 104 |
+
"""
|
| 105 |
+
G = nx.empty_graph(0, create_using, default=nx.MultiGraph)
|
| 106 |
+
if G.is_directed():
|
| 107 |
+
raise nx.NetworkXError("Directed Graph not supported")
|
| 108 |
+
|
| 109 |
+
# length and sum of each sequence
|
| 110 |
+
lena = len(aseq)
|
| 111 |
+
lenb = len(bseq)
|
| 112 |
+
suma = sum(aseq)
|
| 113 |
+
sumb = sum(bseq)
|
| 114 |
+
|
| 115 |
+
if not suma == sumb:
|
| 116 |
+
raise nx.NetworkXError(
|
| 117 |
+
f"invalid degree sequences, sum(aseq)!=sum(bseq),{suma},{sumb}"
|
| 118 |
+
)
|
| 119 |
+
|
| 120 |
+
G = _add_nodes_with_bipartite_label(G, lena, lenb)
|
| 121 |
+
|
| 122 |
+
if len(aseq) == 0 or max(aseq) == 0:
|
| 123 |
+
return G # done if no edges
|
| 124 |
+
|
| 125 |
+
# build lists of degree-repeated vertex numbers
|
| 126 |
+
stubs = [[v] * aseq[v] for v in range(lena)]
|
| 127 |
+
astubs = [x for subseq in stubs for x in subseq]
|
| 128 |
+
|
| 129 |
+
stubs = [[v] * bseq[v - lena] for v in range(lena, lena + lenb)]
|
| 130 |
+
bstubs = [x for subseq in stubs for x in subseq]
|
| 131 |
+
|
| 132 |
+
# shuffle lists
|
| 133 |
+
seed.shuffle(astubs)
|
| 134 |
+
seed.shuffle(bstubs)
|
| 135 |
+
|
| 136 |
+
G.add_edges_from([astubs[i], bstubs[i]] for i in range(suma))
|
| 137 |
+
|
| 138 |
+
G.name = "bipartite_configuration_model"
|
| 139 |
+
return G
|
| 140 |
+
|
| 141 |
+
|
| 142 |
+
@nx._dispatchable(name="bipartite_havel_hakimi_graph", graphs=None, returns_graph=True)
|
| 143 |
+
def havel_hakimi_graph(aseq, bseq, create_using=None):
|
| 144 |
+
"""Returns a bipartite graph from two given degree sequences using a
|
| 145 |
+
Havel-Hakimi style construction.
|
| 146 |
+
|
| 147 |
+
The graph is composed of two partitions. Set A has nodes 0 to
|
| 148 |
+
(len(aseq) - 1) and set B has nodes len(aseq) to (len(bseq) - 1).
|
| 149 |
+
Nodes from the set A are connected to nodes in the set B by
|
| 150 |
+
connecting the highest degree nodes in set A to the highest degree
|
| 151 |
+
nodes in set B until all stubs are connected.
|
| 152 |
+
|
| 153 |
+
Parameters
|
| 154 |
+
----------
|
| 155 |
+
aseq : list
|
| 156 |
+
Degree sequence for node set A.
|
| 157 |
+
bseq : list
|
| 158 |
+
Degree sequence for node set B.
|
| 159 |
+
create_using : NetworkX graph instance, optional
|
| 160 |
+
Return graph of this type.
|
| 161 |
+
|
| 162 |
+
Notes
|
| 163 |
+
-----
|
| 164 |
+
The sum of the two sequences must be equal: sum(aseq)=sum(bseq)
|
| 165 |
+
If no graph type is specified use MultiGraph with parallel edges.
|
| 166 |
+
If you want a graph with no parallel edges use create_using=Graph()
|
| 167 |
+
but then the resulting degree sequences might not be exact.
|
| 168 |
+
|
| 169 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 170 |
+
to indicate which bipartite set the node belongs to.
|
| 171 |
+
|
| 172 |
+
This function is not imported in the main namespace.
|
| 173 |
+
To use it use nx.bipartite.havel_hakimi_graph
|
| 174 |
+
"""
|
| 175 |
+
G = nx.empty_graph(0, create_using, default=nx.MultiGraph)
|
| 176 |
+
if G.is_directed():
|
| 177 |
+
raise nx.NetworkXError("Directed Graph not supported")
|
| 178 |
+
|
| 179 |
+
# length of the each sequence
|
| 180 |
+
naseq = len(aseq)
|
| 181 |
+
nbseq = len(bseq)
|
| 182 |
+
|
| 183 |
+
suma = sum(aseq)
|
| 184 |
+
sumb = sum(bseq)
|
| 185 |
+
|
| 186 |
+
if not suma == sumb:
|
| 187 |
+
raise nx.NetworkXError(
|
| 188 |
+
f"invalid degree sequences, sum(aseq)!=sum(bseq),{suma},{sumb}"
|
| 189 |
+
)
|
| 190 |
+
|
| 191 |
+
G = _add_nodes_with_bipartite_label(G, naseq, nbseq)
|
| 192 |
+
|
| 193 |
+
if len(aseq) == 0 or max(aseq) == 0:
|
| 194 |
+
return G # done if no edges
|
| 195 |
+
|
| 196 |
+
# build list of degree-repeated vertex numbers
|
| 197 |
+
astubs = [[aseq[v], v] for v in range(naseq)]
|
| 198 |
+
bstubs = [[bseq[v - naseq], v] for v in range(naseq, naseq + nbseq)]
|
| 199 |
+
astubs.sort()
|
| 200 |
+
while astubs:
|
| 201 |
+
(degree, u) = astubs.pop() # take of largest degree node in the a set
|
| 202 |
+
if degree == 0:
|
| 203 |
+
break # done, all are zero
|
| 204 |
+
# connect the source to largest degree nodes in the b set
|
| 205 |
+
bstubs.sort()
|
| 206 |
+
for target in bstubs[-degree:]:
|
| 207 |
+
v = target[1]
|
| 208 |
+
G.add_edge(u, v)
|
| 209 |
+
target[0] -= 1 # note this updates bstubs too.
|
| 210 |
+
if target[0] == 0:
|
| 211 |
+
bstubs.remove(target)
|
| 212 |
+
|
| 213 |
+
G.name = "bipartite_havel_hakimi_graph"
|
| 214 |
+
return G
|
| 215 |
+
|
| 216 |
+
|
| 217 |
+
@nx._dispatchable(graphs=None, returns_graph=True)
|
| 218 |
+
def reverse_havel_hakimi_graph(aseq, bseq, create_using=None):
|
| 219 |
+
"""Returns a bipartite graph from two given degree sequences using a
|
| 220 |
+
Havel-Hakimi style construction.
|
| 221 |
+
|
| 222 |
+
The graph is composed of two partitions. Set A has nodes 0 to
|
| 223 |
+
(len(aseq) - 1) and set B has nodes len(aseq) to (len(bseq) - 1).
|
| 224 |
+
Nodes from set A are connected to nodes in the set B by connecting
|
| 225 |
+
the highest degree nodes in set A to the lowest degree nodes in
|
| 226 |
+
set B until all stubs are connected.
|
| 227 |
+
|
| 228 |
+
Parameters
|
| 229 |
+
----------
|
| 230 |
+
aseq : list
|
| 231 |
+
Degree sequence for node set A.
|
| 232 |
+
bseq : list
|
| 233 |
+
Degree sequence for node set B.
|
| 234 |
+
create_using : NetworkX graph instance, optional
|
| 235 |
+
Return graph of this type.
|
| 236 |
+
|
| 237 |
+
Notes
|
| 238 |
+
-----
|
| 239 |
+
The sum of the two sequences must be equal: sum(aseq)=sum(bseq)
|
| 240 |
+
If no graph type is specified use MultiGraph with parallel edges.
|
| 241 |
+
If you want a graph with no parallel edges use create_using=Graph()
|
| 242 |
+
but then the resulting degree sequences might not be exact.
|
| 243 |
+
|
| 244 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 245 |
+
to indicate which bipartite set the node belongs to.
|
| 246 |
+
|
| 247 |
+
This function is not imported in the main namespace.
|
| 248 |
+
To use it use nx.bipartite.reverse_havel_hakimi_graph
|
| 249 |
+
"""
|
| 250 |
+
G = nx.empty_graph(0, create_using, default=nx.MultiGraph)
|
| 251 |
+
if G.is_directed():
|
| 252 |
+
raise nx.NetworkXError("Directed Graph not supported")
|
| 253 |
+
|
| 254 |
+
# length of the each sequence
|
| 255 |
+
lena = len(aseq)
|
| 256 |
+
lenb = len(bseq)
|
| 257 |
+
suma = sum(aseq)
|
| 258 |
+
sumb = sum(bseq)
|
| 259 |
+
|
| 260 |
+
if not suma == sumb:
|
| 261 |
+
raise nx.NetworkXError(
|
| 262 |
+
f"invalid degree sequences, sum(aseq)!=sum(bseq),{suma},{sumb}"
|
| 263 |
+
)
|
| 264 |
+
|
| 265 |
+
G = _add_nodes_with_bipartite_label(G, lena, lenb)
|
| 266 |
+
|
| 267 |
+
if len(aseq) == 0 or max(aseq) == 0:
|
| 268 |
+
return G # done if no edges
|
| 269 |
+
|
| 270 |
+
# build list of degree-repeated vertex numbers
|
| 271 |
+
astubs = [[aseq[v], v] for v in range(lena)]
|
| 272 |
+
bstubs = [[bseq[v - lena], v] for v in range(lena, lena + lenb)]
|
| 273 |
+
astubs.sort()
|
| 274 |
+
bstubs.sort()
|
| 275 |
+
while astubs:
|
| 276 |
+
(degree, u) = astubs.pop() # take of largest degree node in the a set
|
| 277 |
+
if degree == 0:
|
| 278 |
+
break # done, all are zero
|
| 279 |
+
# connect the source to the smallest degree nodes in the b set
|
| 280 |
+
for target in bstubs[0:degree]:
|
| 281 |
+
v = target[1]
|
| 282 |
+
G.add_edge(u, v)
|
| 283 |
+
target[0] -= 1 # note this updates bstubs too.
|
| 284 |
+
if target[0] == 0:
|
| 285 |
+
bstubs.remove(target)
|
| 286 |
+
|
| 287 |
+
G.name = "bipartite_reverse_havel_hakimi_graph"
|
| 288 |
+
return G
|
| 289 |
+
|
| 290 |
+
|
| 291 |
+
@nx._dispatchable(graphs=None, returns_graph=True)
|
| 292 |
+
def alternating_havel_hakimi_graph(aseq, bseq, create_using=None):
|
| 293 |
+
"""Returns a bipartite graph from two given degree sequences using
|
| 294 |
+
an alternating Havel-Hakimi style construction.
|
| 295 |
+
|
| 296 |
+
The graph is composed of two partitions. Set A has nodes 0 to
|
| 297 |
+
(len(aseq) - 1) and set B has nodes len(aseq) to (len(bseq) - 1).
|
| 298 |
+
Nodes from the set A are connected to nodes in the set B by
|
| 299 |
+
connecting the highest degree nodes in set A to alternatively the
|
| 300 |
+
highest and the lowest degree nodes in set B until all stubs are
|
| 301 |
+
connected.
|
| 302 |
+
|
| 303 |
+
Parameters
|
| 304 |
+
----------
|
| 305 |
+
aseq : list
|
| 306 |
+
Degree sequence for node set A.
|
| 307 |
+
bseq : list
|
| 308 |
+
Degree sequence for node set B.
|
| 309 |
+
create_using : NetworkX graph instance, optional
|
| 310 |
+
Return graph of this type.
|
| 311 |
+
|
| 312 |
+
Notes
|
| 313 |
+
-----
|
| 314 |
+
The sum of the two sequences must be equal: sum(aseq)=sum(bseq)
|
| 315 |
+
If no graph type is specified use MultiGraph with parallel edges.
|
| 316 |
+
If you want a graph with no parallel edges use create_using=Graph()
|
| 317 |
+
but then the resulting degree sequences might not be exact.
|
| 318 |
+
|
| 319 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 320 |
+
to indicate which bipartite set the node belongs to.
|
| 321 |
+
|
| 322 |
+
This function is not imported in the main namespace.
|
| 323 |
+
To use it use nx.bipartite.alternating_havel_hakimi_graph
|
| 324 |
+
"""
|
| 325 |
+
G = nx.empty_graph(0, create_using, default=nx.MultiGraph)
|
| 326 |
+
if G.is_directed():
|
| 327 |
+
raise nx.NetworkXError("Directed Graph not supported")
|
| 328 |
+
|
| 329 |
+
# length of the each sequence
|
| 330 |
+
naseq = len(aseq)
|
| 331 |
+
nbseq = len(bseq)
|
| 332 |
+
suma = sum(aseq)
|
| 333 |
+
sumb = sum(bseq)
|
| 334 |
+
|
| 335 |
+
if not suma == sumb:
|
| 336 |
+
raise nx.NetworkXError(
|
| 337 |
+
f"invalid degree sequences, sum(aseq)!=sum(bseq),{suma},{sumb}"
|
| 338 |
+
)
|
| 339 |
+
|
| 340 |
+
G = _add_nodes_with_bipartite_label(G, naseq, nbseq)
|
| 341 |
+
|
| 342 |
+
if len(aseq) == 0 or max(aseq) == 0:
|
| 343 |
+
return G # done if no edges
|
| 344 |
+
# build list of degree-repeated vertex numbers
|
| 345 |
+
astubs = [[aseq[v], v] for v in range(naseq)]
|
| 346 |
+
bstubs = [[bseq[v - naseq], v] for v in range(naseq, naseq + nbseq)]
|
| 347 |
+
while astubs:
|
| 348 |
+
astubs.sort()
|
| 349 |
+
(degree, u) = astubs.pop() # take of largest degree node in the a set
|
| 350 |
+
if degree == 0:
|
| 351 |
+
break # done, all are zero
|
| 352 |
+
bstubs.sort()
|
| 353 |
+
small = bstubs[0 : degree // 2] # add these low degree targets
|
| 354 |
+
large = bstubs[(-degree + degree // 2) :] # now high degree targets
|
| 355 |
+
stubs = [x for z in zip(large, small) for x in z] # combine, sorry
|
| 356 |
+
if len(stubs) < len(small) + len(large): # check for zip truncation
|
| 357 |
+
stubs.append(large.pop())
|
| 358 |
+
for target in stubs:
|
| 359 |
+
v = target[1]
|
| 360 |
+
G.add_edge(u, v)
|
| 361 |
+
target[0] -= 1 # note this updates bstubs too.
|
| 362 |
+
if target[0] == 0:
|
| 363 |
+
bstubs.remove(target)
|
| 364 |
+
|
| 365 |
+
G.name = "bipartite_alternating_havel_hakimi_graph"
|
| 366 |
+
return G
|
| 367 |
+
|
| 368 |
+
|
| 369 |
+
@py_random_state(3)
|
| 370 |
+
@nx._dispatchable(graphs=None, returns_graph=True)
|
| 371 |
+
def preferential_attachment_graph(aseq, p, create_using=None, seed=None):
|
| 372 |
+
"""Create a bipartite graph with a preferential attachment model from
|
| 373 |
+
a given single degree sequence.
|
| 374 |
+
|
| 375 |
+
The graph is composed of two partitions. Set A has nodes 0 to
|
| 376 |
+
(len(aseq) - 1) and set B has nodes starting with node len(aseq).
|
| 377 |
+
The number of nodes in set B is random.
|
| 378 |
+
|
| 379 |
+
Parameters
|
| 380 |
+
----------
|
| 381 |
+
aseq : list
|
| 382 |
+
Degree sequence for node set A.
|
| 383 |
+
p : float
|
| 384 |
+
Probability that a new bottom node is added.
|
| 385 |
+
create_using : NetworkX graph instance, optional
|
| 386 |
+
Return graph of this type.
|
| 387 |
+
seed : integer, random_state, or None (default)
|
| 388 |
+
Indicator of random number generation state.
|
| 389 |
+
See :ref:`Randomness<randomness>`.
|
| 390 |
+
|
| 391 |
+
References
|
| 392 |
+
----------
|
| 393 |
+
.. [1] Guillaume, J.L. and Latapy, M.,
|
| 394 |
+
Bipartite graphs as models of complex networks.
|
| 395 |
+
Physica A: Statistical Mechanics and its Applications,
|
| 396 |
+
2006, 371(2), pp.795-813.
|
| 397 |
+
.. [2] Jean-Loup Guillaume and Matthieu Latapy,
|
| 398 |
+
Bipartite structure of all complex networks,
|
| 399 |
+
Inf. Process. Lett. 90, 2004, pg. 215-221
|
| 400 |
+
https://doi.org/10.1016/j.ipl.2004.03.007
|
| 401 |
+
|
| 402 |
+
Notes
|
| 403 |
+
-----
|
| 404 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 405 |
+
to indicate which bipartite set the node belongs to.
|
| 406 |
+
|
| 407 |
+
This function is not imported in the main namespace.
|
| 408 |
+
To use it use nx.bipartite.preferential_attachment_graph
|
| 409 |
+
"""
|
| 410 |
+
G = nx.empty_graph(0, create_using, default=nx.MultiGraph)
|
| 411 |
+
if G.is_directed():
|
| 412 |
+
raise nx.NetworkXError("Directed Graph not supported")
|
| 413 |
+
|
| 414 |
+
if p > 1:
|
| 415 |
+
raise nx.NetworkXError(f"probability {p} > 1")
|
| 416 |
+
|
| 417 |
+
naseq = len(aseq)
|
| 418 |
+
G = _add_nodes_with_bipartite_label(G, naseq, 0)
|
| 419 |
+
vv = [[v] * aseq[v] for v in range(naseq)]
|
| 420 |
+
while vv:
|
| 421 |
+
while vv[0]:
|
| 422 |
+
source = vv[0][0]
|
| 423 |
+
vv[0].remove(source)
|
| 424 |
+
if seed.random() < p or len(G) == naseq:
|
| 425 |
+
target = len(G)
|
| 426 |
+
G.add_node(target, bipartite=1)
|
| 427 |
+
G.add_edge(source, target)
|
| 428 |
+
else:
|
| 429 |
+
bb = [[b] * G.degree(b) for b in range(naseq, len(G))]
|
| 430 |
+
# flatten the list of lists into a list.
|
| 431 |
+
bbstubs = reduce(lambda x, y: x + y, bb)
|
| 432 |
+
# choose preferentially a bottom node.
|
| 433 |
+
target = seed.choice(bbstubs)
|
| 434 |
+
G.add_node(target, bipartite=1)
|
| 435 |
+
G.add_edge(source, target)
|
| 436 |
+
vv.remove(vv[0])
|
| 437 |
+
G.name = "bipartite_preferential_attachment_model"
|
| 438 |
+
return G
|
| 439 |
+
|
| 440 |
+
|
| 441 |
+
@py_random_state(3)
|
| 442 |
+
@nx._dispatchable(graphs=None, returns_graph=True)
|
| 443 |
+
def random_graph(n, m, p, seed=None, directed=False):
|
| 444 |
+
"""Returns a bipartite random graph.
|
| 445 |
+
|
| 446 |
+
This is a bipartite version of the binomial (Erdős-Rényi) graph.
|
| 447 |
+
The graph is composed of two partitions. Set A has nodes 0 to
|
| 448 |
+
(n - 1) and set B has nodes n to (n + m - 1).
|
| 449 |
+
|
| 450 |
+
Parameters
|
| 451 |
+
----------
|
| 452 |
+
n : int
|
| 453 |
+
The number of nodes in the first bipartite set.
|
| 454 |
+
m : int
|
| 455 |
+
The number of nodes in the second bipartite set.
|
| 456 |
+
p : float
|
| 457 |
+
Probability for edge creation.
|
| 458 |
+
seed : integer, random_state, or None (default)
|
| 459 |
+
Indicator of random number generation state.
|
| 460 |
+
See :ref:`Randomness<randomness>`.
|
| 461 |
+
directed : bool, optional (default=False)
|
| 462 |
+
If True return a directed graph
|
| 463 |
+
|
| 464 |
+
Notes
|
| 465 |
+
-----
|
| 466 |
+
The bipartite random graph algorithm chooses each of the n*m (undirected)
|
| 467 |
+
or 2*nm (directed) possible edges with probability p.
|
| 468 |
+
|
| 469 |
+
This algorithm is $O(n+m)$ where $m$ is the expected number of edges.
|
| 470 |
+
|
| 471 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 472 |
+
to indicate which bipartite set the node belongs to.
|
| 473 |
+
|
| 474 |
+
This function is not imported in the main namespace.
|
| 475 |
+
To use it use nx.bipartite.random_graph
|
| 476 |
+
|
| 477 |
+
See Also
|
| 478 |
+
--------
|
| 479 |
+
gnp_random_graph, configuration_model
|
| 480 |
+
|
| 481 |
+
References
|
| 482 |
+
----------
|
| 483 |
+
.. [1] Vladimir Batagelj and Ulrik Brandes,
|
| 484 |
+
"Efficient generation of large random networks",
|
| 485 |
+
Phys. Rev. E, 71, 036113, 2005.
|
| 486 |
+
"""
|
| 487 |
+
G = nx.Graph()
|
| 488 |
+
G = _add_nodes_with_bipartite_label(G, n, m)
|
| 489 |
+
if directed:
|
| 490 |
+
G = nx.DiGraph(G)
|
| 491 |
+
G.name = f"fast_gnp_random_graph({n},{m},{p})"
|
| 492 |
+
|
| 493 |
+
if p <= 0:
|
| 494 |
+
return G
|
| 495 |
+
if p >= 1:
|
| 496 |
+
return nx.complete_bipartite_graph(n, m)
|
| 497 |
+
|
| 498 |
+
lp = math.log(1.0 - p)
|
| 499 |
+
|
| 500 |
+
v = 0
|
| 501 |
+
w = -1
|
| 502 |
+
while v < n:
|
| 503 |
+
lr = math.log(1.0 - seed.random())
|
| 504 |
+
w = w + 1 + int(lr / lp)
|
| 505 |
+
while w >= m and v < n:
|
| 506 |
+
w = w - m
|
| 507 |
+
v = v + 1
|
| 508 |
+
if v < n:
|
| 509 |
+
G.add_edge(v, n + w)
|
| 510 |
+
|
| 511 |
+
if directed:
|
| 512 |
+
# use the same algorithm to
|
| 513 |
+
# add edges from the "m" to "n" set
|
| 514 |
+
v = 0
|
| 515 |
+
w = -1
|
| 516 |
+
while v < n:
|
| 517 |
+
lr = math.log(1.0 - seed.random())
|
| 518 |
+
w = w + 1 + int(lr / lp)
|
| 519 |
+
while w >= m and v < n:
|
| 520 |
+
w = w - m
|
| 521 |
+
v = v + 1
|
| 522 |
+
if v < n:
|
| 523 |
+
G.add_edge(n + w, v)
|
| 524 |
+
|
| 525 |
+
return G
|
| 526 |
+
|
| 527 |
+
|
| 528 |
+
@py_random_state(3)
|
| 529 |
+
@nx._dispatchable(graphs=None, returns_graph=True)
|
| 530 |
+
def gnmk_random_graph(n, m, k, seed=None, directed=False):
|
| 531 |
+
"""Returns a random bipartite graph G_{n,m,k}.
|
| 532 |
+
|
| 533 |
+
Produces a bipartite graph chosen randomly out of the set of all graphs
|
| 534 |
+
with n top nodes, m bottom nodes, and k edges.
|
| 535 |
+
The graph is composed of two sets of nodes.
|
| 536 |
+
Set A has nodes 0 to (n - 1) and set B has nodes n to (n + m - 1).
|
| 537 |
+
|
| 538 |
+
Parameters
|
| 539 |
+
----------
|
| 540 |
+
n : int
|
| 541 |
+
The number of nodes in the first bipartite set.
|
| 542 |
+
m : int
|
| 543 |
+
The number of nodes in the second bipartite set.
|
| 544 |
+
k : int
|
| 545 |
+
The number of edges
|
| 546 |
+
seed : integer, random_state, or None (default)
|
| 547 |
+
Indicator of random number generation state.
|
| 548 |
+
See :ref:`Randomness<randomness>`.
|
| 549 |
+
directed : bool, optional (default=False)
|
| 550 |
+
If True return a directed graph
|
| 551 |
+
|
| 552 |
+
Examples
|
| 553 |
+
--------
|
| 554 |
+
>>> G = nx.bipartite.gnmk_random_graph(10, 20, 50)
|
| 555 |
+
|
| 556 |
+
See Also
|
| 557 |
+
--------
|
| 558 |
+
gnm_random_graph
|
| 559 |
+
|
| 560 |
+
Notes
|
| 561 |
+
-----
|
| 562 |
+
If k > m * n then a complete bipartite graph is returned.
|
| 563 |
+
|
| 564 |
+
This graph is a bipartite version of the `G_{nm}` random graph model.
|
| 565 |
+
|
| 566 |
+
The nodes are assigned the attribute 'bipartite' with the value 0 or 1
|
| 567 |
+
to indicate which bipartite set the node belongs to.
|
| 568 |
+
|
| 569 |
+
This function is not imported in the main namespace.
|
| 570 |
+
To use it use nx.bipartite.gnmk_random_graph
|
| 571 |
+
"""
|
| 572 |
+
G = nx.Graph()
|
| 573 |
+
G = _add_nodes_with_bipartite_label(G, n, m)
|
| 574 |
+
if directed:
|
| 575 |
+
G = nx.DiGraph(G)
|
| 576 |
+
G.name = f"bipartite_gnm_random_graph({n},{m},{k})"
|
| 577 |
+
if n == 1 or m == 1:
|
| 578 |
+
return G
|
| 579 |
+
max_edges = n * m # max_edges for bipartite networks
|
| 580 |
+
if k >= max_edges: # Maybe we should raise an exception here
|
| 581 |
+
return nx.complete_bipartite_graph(n, m, create_using=G)
|
| 582 |
+
|
| 583 |
+
top = [n for n, d in G.nodes(data=True) if d["bipartite"] == 0]
|
| 584 |
+
bottom = list(set(G) - set(top))
|
| 585 |
+
edge_count = 0
|
| 586 |
+
while edge_count < k:
|
| 587 |
+
# generate random edge,u,v
|
| 588 |
+
u = seed.choice(top)
|
| 589 |
+
v = seed.choice(bottom)
|
| 590 |
+
if v in G[u]:
|
| 591 |
+
continue
|
| 592 |
+
else:
|
| 593 |
+
G.add_edge(u, v)
|
| 594 |
+
edge_count += 1
|
| 595 |
+
return G
|
| 596 |
+
|
| 597 |
+
|
| 598 |
+
def _add_nodes_with_bipartite_label(G, lena, lenb):
|
| 599 |
+
G.add_nodes_from(range(lena + lenb))
|
| 600 |
+
b = dict(zip(range(lena), [0] * lena))
|
| 601 |
+
b.update(dict(zip(range(lena, lena + lenb), [1] * lenb)))
|
| 602 |
+
nx.set_node_attributes(G, b, "bipartite")
|
| 603 |
+
return G
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/boundary.py
ADDED
|
@@ -0,0 +1,168 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Routines to find the boundary of a set of nodes.
|
| 2 |
+
|
| 3 |
+
An edge boundary is a set of edges, each of which has exactly one
|
| 4 |
+
endpoint in a given set of nodes (or, in the case of directed graphs,
|
| 5 |
+
the set of edges whose source node is in the set).
|
| 6 |
+
|
| 7 |
+
A node boundary of a set *S* of nodes is the set of (out-)neighbors of
|
| 8 |
+
nodes in *S* that are outside *S*.
|
| 9 |
+
|
| 10 |
+
"""
|
| 11 |
+
|
| 12 |
+
from itertools import chain
|
| 13 |
+
|
| 14 |
+
import networkx as nx
|
| 15 |
+
|
| 16 |
+
__all__ = ["edge_boundary", "node_boundary"]
|
| 17 |
+
|
| 18 |
+
|
| 19 |
+
@nx._dispatchable(edge_attrs={"data": "default"}, preserve_edge_attrs="data")
|
| 20 |
+
def edge_boundary(G, nbunch1, nbunch2=None, data=False, keys=False, default=None):
|
| 21 |
+
"""Returns the edge boundary of `nbunch1`.
|
| 22 |
+
|
| 23 |
+
The *edge boundary* of a set *S* with respect to a set *T* is the
|
| 24 |
+
set of edges (*u*, *v*) such that *u* is in *S* and *v* is in *T*.
|
| 25 |
+
If *T* is not specified, it is assumed to be the set of all nodes
|
| 26 |
+
not in *S*.
|
| 27 |
+
|
| 28 |
+
Parameters
|
| 29 |
+
----------
|
| 30 |
+
G : NetworkX graph
|
| 31 |
+
|
| 32 |
+
nbunch1 : iterable
|
| 33 |
+
Iterable of nodes in the graph representing the set of nodes
|
| 34 |
+
whose edge boundary will be returned. (This is the set *S* from
|
| 35 |
+
the definition above.)
|
| 36 |
+
|
| 37 |
+
nbunch2 : iterable
|
| 38 |
+
Iterable of nodes representing the target (or "exterior") set of
|
| 39 |
+
nodes. (This is the set *T* from the definition above.) If not
|
| 40 |
+
specified, this is assumed to be the set of all nodes in `G`
|
| 41 |
+
not in `nbunch1`.
|
| 42 |
+
|
| 43 |
+
keys : bool
|
| 44 |
+
This parameter has the same meaning as in
|
| 45 |
+
:meth:`MultiGraph.edges`.
|
| 46 |
+
|
| 47 |
+
data : bool or object
|
| 48 |
+
This parameter has the same meaning as in
|
| 49 |
+
:meth:`MultiGraph.edges`.
|
| 50 |
+
|
| 51 |
+
default : object
|
| 52 |
+
This parameter has the same meaning as in
|
| 53 |
+
:meth:`MultiGraph.edges`.
|
| 54 |
+
|
| 55 |
+
Returns
|
| 56 |
+
-------
|
| 57 |
+
iterator
|
| 58 |
+
An iterator over the edges in the boundary of `nbunch1` with
|
| 59 |
+
respect to `nbunch2`. If `keys`, `data`, or `default`
|
| 60 |
+
are specified and `G` is a multigraph, then edges are returned
|
| 61 |
+
with keys and/or data, as in :meth:`MultiGraph.edges`.
|
| 62 |
+
|
| 63 |
+
Examples
|
| 64 |
+
--------
|
| 65 |
+
>>> G = nx.wheel_graph(6)
|
| 66 |
+
|
| 67 |
+
When nbunch2=None:
|
| 68 |
+
|
| 69 |
+
>>> list(nx.edge_boundary(G, (1, 3)))
|
| 70 |
+
[(1, 0), (1, 2), (1, 5), (3, 0), (3, 2), (3, 4)]
|
| 71 |
+
|
| 72 |
+
When nbunch2 is given:
|
| 73 |
+
|
| 74 |
+
>>> list(nx.edge_boundary(G, (1, 3), (2, 0)))
|
| 75 |
+
[(1, 0), (1, 2), (3, 0), (3, 2)]
|
| 76 |
+
|
| 77 |
+
Notes
|
| 78 |
+
-----
|
| 79 |
+
Any element of `nbunch` that is not in the graph `G` will be
|
| 80 |
+
ignored.
|
| 81 |
+
|
| 82 |
+
`nbunch1` and `nbunch2` are usually meant to be disjoint, but in
|
| 83 |
+
the interest of speed and generality, that is not required here.
|
| 84 |
+
|
| 85 |
+
"""
|
| 86 |
+
nset1 = {n for n in nbunch1 if n in G}
|
| 87 |
+
# Here we create an iterator over edges incident to nodes in the set
|
| 88 |
+
# `nset1`. The `Graph.edges()` method does not provide a guarantee
|
| 89 |
+
# on the orientation of the edges, so our algorithm below must
|
| 90 |
+
# handle the case in which exactly one orientation, either (u, v) or
|
| 91 |
+
# (v, u), appears in this iterable.
|
| 92 |
+
if G.is_multigraph():
|
| 93 |
+
edges = G.edges(nset1, data=data, keys=keys, default=default)
|
| 94 |
+
else:
|
| 95 |
+
edges = G.edges(nset1, data=data, default=default)
|
| 96 |
+
# If `nbunch2` is not provided, then it is assumed to be the set
|
| 97 |
+
# complement of `nbunch1`. For the sake of efficiency, this is
|
| 98 |
+
# implemented by using the `not in` operator, instead of by creating
|
| 99 |
+
# an additional set and using the `in` operator.
|
| 100 |
+
if nbunch2 is None:
|
| 101 |
+
return (e for e in edges if (e[0] in nset1) ^ (e[1] in nset1))
|
| 102 |
+
nset2 = set(nbunch2)
|
| 103 |
+
return (
|
| 104 |
+
e
|
| 105 |
+
for e in edges
|
| 106 |
+
if (e[0] in nset1 and e[1] in nset2) or (e[1] in nset1 and e[0] in nset2)
|
| 107 |
+
)
|
| 108 |
+
|
| 109 |
+
|
| 110 |
+
@nx._dispatchable
|
| 111 |
+
def node_boundary(G, nbunch1, nbunch2=None):
|
| 112 |
+
"""Returns the node boundary of `nbunch1`.
|
| 113 |
+
|
| 114 |
+
The *node boundary* of a set *S* with respect to a set *T* is the
|
| 115 |
+
set of nodes *v* in *T* such that for some *u* in *S*, there is an
|
| 116 |
+
edge joining *u* to *v*. If *T* is not specified, it is assumed to
|
| 117 |
+
be the set of all nodes not in *S*.
|
| 118 |
+
|
| 119 |
+
Parameters
|
| 120 |
+
----------
|
| 121 |
+
G : NetworkX graph
|
| 122 |
+
|
| 123 |
+
nbunch1 : iterable
|
| 124 |
+
Iterable of nodes in the graph representing the set of nodes
|
| 125 |
+
whose node boundary will be returned. (This is the set *S* from
|
| 126 |
+
the definition above.)
|
| 127 |
+
|
| 128 |
+
nbunch2 : iterable
|
| 129 |
+
Iterable of nodes representing the target (or "exterior") set of
|
| 130 |
+
nodes. (This is the set *T* from the definition above.) If not
|
| 131 |
+
specified, this is assumed to be the set of all nodes in `G`
|
| 132 |
+
not in `nbunch1`.
|
| 133 |
+
|
| 134 |
+
Returns
|
| 135 |
+
-------
|
| 136 |
+
set
|
| 137 |
+
The node boundary of `nbunch1` with respect to `nbunch2`.
|
| 138 |
+
|
| 139 |
+
Examples
|
| 140 |
+
--------
|
| 141 |
+
>>> G = nx.wheel_graph(6)
|
| 142 |
+
|
| 143 |
+
When nbunch2=None:
|
| 144 |
+
|
| 145 |
+
>>> list(nx.node_boundary(G, (3, 4)))
|
| 146 |
+
[0, 2, 5]
|
| 147 |
+
|
| 148 |
+
When nbunch2 is given:
|
| 149 |
+
|
| 150 |
+
>>> list(nx.node_boundary(G, (3, 4), (0, 1, 5)))
|
| 151 |
+
[0, 5]
|
| 152 |
+
|
| 153 |
+
Notes
|
| 154 |
+
-----
|
| 155 |
+
Any element of `nbunch` that is not in the graph `G` will be
|
| 156 |
+
ignored.
|
| 157 |
+
|
| 158 |
+
`nbunch1` and `nbunch2` are usually meant to be disjoint, but in
|
| 159 |
+
the interest of speed and generality, that is not required here.
|
| 160 |
+
|
| 161 |
+
"""
|
| 162 |
+
nset1 = {n for n in nbunch1 if n in G}
|
| 163 |
+
bdy = set(chain.from_iterable(G[v] for v in nset1)) - nset1
|
| 164 |
+
# If `nbunch2` is not specified, it is assumed to be the set
|
| 165 |
+
# complement of `nbunch1`.
|
| 166 |
+
if nbunch2 is not None:
|
| 167 |
+
bdy &= set(nbunch2)
|
| 168 |
+
return bdy
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/bridges.py
ADDED
|
@@ -0,0 +1,205 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Bridge-finding algorithms."""
|
| 2 |
+
|
| 3 |
+
from itertools import chain
|
| 4 |
+
|
| 5 |
+
import networkx as nx
|
| 6 |
+
from networkx.utils import not_implemented_for
|
| 7 |
+
|
| 8 |
+
__all__ = ["bridges", "has_bridges", "local_bridges"]
|
| 9 |
+
|
| 10 |
+
|
| 11 |
+
@not_implemented_for("directed")
|
| 12 |
+
@nx._dispatchable
|
| 13 |
+
def bridges(G, root=None):
|
| 14 |
+
"""Generate all bridges in a graph.
|
| 15 |
+
|
| 16 |
+
A *bridge* in a graph is an edge whose removal causes the number of
|
| 17 |
+
connected components of the graph to increase. Equivalently, a bridge is an
|
| 18 |
+
edge that does not belong to any cycle. Bridges are also known as cut-edges,
|
| 19 |
+
isthmuses, or cut arcs.
|
| 20 |
+
|
| 21 |
+
Parameters
|
| 22 |
+
----------
|
| 23 |
+
G : undirected graph
|
| 24 |
+
|
| 25 |
+
root : node (optional)
|
| 26 |
+
A node in the graph `G`. If specified, only the bridges in the
|
| 27 |
+
connected component containing this node will be returned.
|
| 28 |
+
|
| 29 |
+
Yields
|
| 30 |
+
------
|
| 31 |
+
e : edge
|
| 32 |
+
An edge in the graph whose removal disconnects the graph (or
|
| 33 |
+
causes the number of connected components to increase).
|
| 34 |
+
|
| 35 |
+
Raises
|
| 36 |
+
------
|
| 37 |
+
NodeNotFound
|
| 38 |
+
If `root` is not in the graph `G`.
|
| 39 |
+
|
| 40 |
+
NetworkXNotImplemented
|
| 41 |
+
If `G` is a directed graph.
|
| 42 |
+
|
| 43 |
+
Examples
|
| 44 |
+
--------
|
| 45 |
+
The barbell graph with parameter zero has a single bridge:
|
| 46 |
+
|
| 47 |
+
>>> G = nx.barbell_graph(10, 0)
|
| 48 |
+
>>> list(nx.bridges(G))
|
| 49 |
+
[(9, 10)]
|
| 50 |
+
|
| 51 |
+
Notes
|
| 52 |
+
-----
|
| 53 |
+
This is an implementation of the algorithm described in [1]_. An edge is a
|
| 54 |
+
bridge if and only if it is not contained in any chain. Chains are found
|
| 55 |
+
using the :func:`networkx.chain_decomposition` function.
|
| 56 |
+
|
| 57 |
+
The algorithm described in [1]_ requires a simple graph. If the provided
|
| 58 |
+
graph is a multigraph, we convert it to a simple graph and verify that any
|
| 59 |
+
bridges discovered by the chain decomposition algorithm are not multi-edges.
|
| 60 |
+
|
| 61 |
+
Ignoring polylogarithmic factors, the worst-case time complexity is the
|
| 62 |
+
same as the :func:`networkx.chain_decomposition` function,
|
| 63 |
+
$O(m + n)$, where $n$ is the number of nodes in the graph and $m$ is
|
| 64 |
+
the number of edges.
|
| 65 |
+
|
| 66 |
+
References
|
| 67 |
+
----------
|
| 68 |
+
.. [1] https://en.wikipedia.org/wiki/Bridge_%28graph_theory%29#Bridge-Finding_with_Chain_Decompositions
|
| 69 |
+
"""
|
| 70 |
+
multigraph = G.is_multigraph()
|
| 71 |
+
H = nx.Graph(G) if multigraph else G
|
| 72 |
+
chains = nx.chain_decomposition(H, root=root)
|
| 73 |
+
chain_edges = set(chain.from_iterable(chains))
|
| 74 |
+
if root is not None:
|
| 75 |
+
H = H.subgraph(nx.node_connected_component(H, root)).copy()
|
| 76 |
+
for u, v in H.edges():
|
| 77 |
+
if (u, v) not in chain_edges and (v, u) not in chain_edges:
|
| 78 |
+
if multigraph and len(G[u][v]) > 1:
|
| 79 |
+
continue
|
| 80 |
+
yield u, v
|
| 81 |
+
|
| 82 |
+
|
| 83 |
+
@not_implemented_for("directed")
|
| 84 |
+
@nx._dispatchable
|
| 85 |
+
def has_bridges(G, root=None):
|
| 86 |
+
"""Decide whether a graph has any bridges.
|
| 87 |
+
|
| 88 |
+
A *bridge* in a graph is an edge whose removal causes the number of
|
| 89 |
+
connected components of the graph to increase.
|
| 90 |
+
|
| 91 |
+
Parameters
|
| 92 |
+
----------
|
| 93 |
+
G : undirected graph
|
| 94 |
+
|
| 95 |
+
root : node (optional)
|
| 96 |
+
A node in the graph `G`. If specified, only the bridges in the
|
| 97 |
+
connected component containing this node will be considered.
|
| 98 |
+
|
| 99 |
+
Returns
|
| 100 |
+
-------
|
| 101 |
+
bool
|
| 102 |
+
Whether the graph (or the connected component containing `root`)
|
| 103 |
+
has any bridges.
|
| 104 |
+
|
| 105 |
+
Raises
|
| 106 |
+
------
|
| 107 |
+
NodeNotFound
|
| 108 |
+
If `root` is not in the graph `G`.
|
| 109 |
+
|
| 110 |
+
NetworkXNotImplemented
|
| 111 |
+
If `G` is a directed graph.
|
| 112 |
+
|
| 113 |
+
Examples
|
| 114 |
+
--------
|
| 115 |
+
The barbell graph with parameter zero has a single bridge::
|
| 116 |
+
|
| 117 |
+
>>> G = nx.barbell_graph(10, 0)
|
| 118 |
+
>>> nx.has_bridges(G)
|
| 119 |
+
True
|
| 120 |
+
|
| 121 |
+
On the other hand, the cycle graph has no bridges::
|
| 122 |
+
|
| 123 |
+
>>> G = nx.cycle_graph(5)
|
| 124 |
+
>>> nx.has_bridges(G)
|
| 125 |
+
False
|
| 126 |
+
|
| 127 |
+
Notes
|
| 128 |
+
-----
|
| 129 |
+
This implementation uses the :func:`networkx.bridges` function, so
|
| 130 |
+
it shares its worst-case time complexity, $O(m + n)$, ignoring
|
| 131 |
+
polylogarithmic factors, where $n$ is the number of nodes in the
|
| 132 |
+
graph and $m$ is the number of edges.
|
| 133 |
+
|
| 134 |
+
"""
|
| 135 |
+
try:
|
| 136 |
+
next(bridges(G, root=root))
|
| 137 |
+
except StopIteration:
|
| 138 |
+
return False
|
| 139 |
+
else:
|
| 140 |
+
return True
|
| 141 |
+
|
| 142 |
+
|
| 143 |
+
@not_implemented_for("multigraph")
|
| 144 |
+
@not_implemented_for("directed")
|
| 145 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 146 |
+
def local_bridges(G, with_span=True, weight=None):
|
| 147 |
+
"""Iterate over local bridges of `G` optionally computing the span
|
| 148 |
+
|
| 149 |
+
A *local bridge* is an edge whose endpoints have no common neighbors.
|
| 150 |
+
That is, the edge is not part of a triangle in the graph.
|
| 151 |
+
|
| 152 |
+
The *span* of a *local bridge* is the shortest path length between
|
| 153 |
+
the endpoints if the local bridge is removed.
|
| 154 |
+
|
| 155 |
+
Parameters
|
| 156 |
+
----------
|
| 157 |
+
G : undirected graph
|
| 158 |
+
|
| 159 |
+
with_span : bool
|
| 160 |
+
If True, yield a 3-tuple `(u, v, span)`
|
| 161 |
+
|
| 162 |
+
weight : function, string or None (default: None)
|
| 163 |
+
If function, used to compute edge weights for the span.
|
| 164 |
+
If string, the edge data attribute used in calculating span.
|
| 165 |
+
If None, all edges have weight 1.
|
| 166 |
+
|
| 167 |
+
Yields
|
| 168 |
+
------
|
| 169 |
+
e : edge
|
| 170 |
+
The local bridges as an edge 2-tuple of nodes `(u, v)` or
|
| 171 |
+
as a 3-tuple `(u, v, span)` when `with_span is True`.
|
| 172 |
+
|
| 173 |
+
Raises
|
| 174 |
+
------
|
| 175 |
+
NetworkXNotImplemented
|
| 176 |
+
If `G` is a directed graph or multigraph.
|
| 177 |
+
|
| 178 |
+
Examples
|
| 179 |
+
--------
|
| 180 |
+
A cycle graph has every edge a local bridge with span N-1.
|
| 181 |
+
|
| 182 |
+
>>> G = nx.cycle_graph(9)
|
| 183 |
+
>>> (0, 8, 8) in set(nx.local_bridges(G))
|
| 184 |
+
True
|
| 185 |
+
"""
|
| 186 |
+
if with_span is not True:
|
| 187 |
+
for u, v in G.edges:
|
| 188 |
+
if not (set(G[u]) & set(G[v])):
|
| 189 |
+
yield u, v
|
| 190 |
+
else:
|
| 191 |
+
wt = nx.weighted._weight_function(G, weight)
|
| 192 |
+
for u, v in G.edges:
|
| 193 |
+
if not (set(G[u]) & set(G[v])):
|
| 194 |
+
enodes = {u, v}
|
| 195 |
+
|
| 196 |
+
def hide_edge(n, nbr, d):
|
| 197 |
+
if n not in enodes or nbr not in enodes:
|
| 198 |
+
return wt(n, nbr, d)
|
| 199 |
+
return None
|
| 200 |
+
|
| 201 |
+
try:
|
| 202 |
+
span = nx.shortest_path_length(G, u, v, weight=hide_edge)
|
| 203 |
+
yield u, v, span
|
| 204 |
+
except nx.NetworkXNoPath:
|
| 205 |
+
yield u, v, float("inf")
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/broadcasting.py
ADDED
|
@@ -0,0 +1,155 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Routines to calculate the broadcast time of certain graphs.
|
| 2 |
+
|
| 3 |
+
Broadcasting is an information dissemination problem in which a node in a graph,
|
| 4 |
+
called the originator, must distribute a message to all other nodes by placing
|
| 5 |
+
a series of calls along the edges of the graph. Once informed, other nodes aid
|
| 6 |
+
the originator in distributing the message.
|
| 7 |
+
|
| 8 |
+
The broadcasting must be completed as quickly as possible subject to the
|
| 9 |
+
following constraints:
|
| 10 |
+
- Each call requires one unit of time.
|
| 11 |
+
- A node can only participate in one call per unit of time.
|
| 12 |
+
- Each call only involves two adjacent nodes: a sender and a receiver.
|
| 13 |
+
"""
|
| 14 |
+
|
| 15 |
+
import networkx as nx
|
| 16 |
+
from networkx import NetworkXError
|
| 17 |
+
from networkx.utils import not_implemented_for
|
| 18 |
+
|
| 19 |
+
__all__ = [
|
| 20 |
+
"tree_broadcast_center",
|
| 21 |
+
"tree_broadcast_time",
|
| 22 |
+
]
|
| 23 |
+
|
| 24 |
+
|
| 25 |
+
def _get_max_broadcast_value(G, U, v, values):
|
| 26 |
+
adj = sorted(set(G.neighbors(v)) & U, key=values.get, reverse=True)
|
| 27 |
+
return max(values[u] + i for i, u in enumerate(adj, start=1))
|
| 28 |
+
|
| 29 |
+
|
| 30 |
+
def _get_broadcast_centers(G, v, values, target):
|
| 31 |
+
adj = sorted(G.neighbors(v), key=values.get, reverse=True)
|
| 32 |
+
j = next(i for i, u in enumerate(adj, start=1) if values[u] + i == target)
|
| 33 |
+
return set([v] + adj[:j])
|
| 34 |
+
|
| 35 |
+
|
| 36 |
+
@not_implemented_for("directed")
|
| 37 |
+
@not_implemented_for("multigraph")
|
| 38 |
+
@nx._dispatchable
|
| 39 |
+
def tree_broadcast_center(G):
|
| 40 |
+
"""Return the Broadcast Center of the tree `G`.
|
| 41 |
+
|
| 42 |
+
The broadcast center of a graph G denotes the set of nodes having
|
| 43 |
+
minimum broadcast time [1]_. This is a linear algorithm for determining
|
| 44 |
+
the broadcast center of a tree with ``N`` nodes, as a by-product it also
|
| 45 |
+
determines the broadcast time from the broadcast center.
|
| 46 |
+
|
| 47 |
+
Parameters
|
| 48 |
+
----------
|
| 49 |
+
G : undirected graph
|
| 50 |
+
The graph should be an undirected tree
|
| 51 |
+
|
| 52 |
+
Returns
|
| 53 |
+
-------
|
| 54 |
+
BC : (int, set) tuple
|
| 55 |
+
minimum broadcast number of the tree, set of broadcast centers
|
| 56 |
+
|
| 57 |
+
Raises
|
| 58 |
+
------
|
| 59 |
+
NetworkXNotImplemented
|
| 60 |
+
If the graph is directed or is a multigraph.
|
| 61 |
+
|
| 62 |
+
References
|
| 63 |
+
----------
|
| 64 |
+
.. [1] Slater, P.J., Cockayne, E.J., Hedetniemi, S.T,
|
| 65 |
+
Information dissemination in trees. SIAM J.Comput. 10(4), 692–701 (1981)
|
| 66 |
+
"""
|
| 67 |
+
# Assert that the graph G is a tree
|
| 68 |
+
if not nx.is_tree(G):
|
| 69 |
+
NetworkXError("Input graph is not a tree")
|
| 70 |
+
# step 0
|
| 71 |
+
if G.number_of_nodes() == 2:
|
| 72 |
+
return 1, set(G.nodes())
|
| 73 |
+
if G.number_of_nodes() == 1:
|
| 74 |
+
return 0, set(G.nodes())
|
| 75 |
+
|
| 76 |
+
# step 1
|
| 77 |
+
U = {node for node, deg in G.degree if deg == 1}
|
| 78 |
+
values = dict.fromkeys(U, 0)
|
| 79 |
+
T = G.copy()
|
| 80 |
+
T.remove_nodes_from(U)
|
| 81 |
+
|
| 82 |
+
# step 2
|
| 83 |
+
W = {node for node, deg in T.degree if deg == 1}
|
| 84 |
+
values.update((w, G.degree[w] - 1) for w in W)
|
| 85 |
+
|
| 86 |
+
# step 3
|
| 87 |
+
while T.number_of_nodes() >= 2:
|
| 88 |
+
# step 4
|
| 89 |
+
w = min(W, key=lambda n: values[n])
|
| 90 |
+
v = next(T.neighbors(w))
|
| 91 |
+
|
| 92 |
+
# step 5
|
| 93 |
+
U.add(w)
|
| 94 |
+
W.remove(w)
|
| 95 |
+
T.remove_node(w)
|
| 96 |
+
|
| 97 |
+
# step 6
|
| 98 |
+
if T.degree(v) == 1:
|
| 99 |
+
# update t(v)
|
| 100 |
+
values.update({v: _get_max_broadcast_value(G, U, v, values)})
|
| 101 |
+
W.add(v)
|
| 102 |
+
|
| 103 |
+
# step 7
|
| 104 |
+
v = nx.utils.arbitrary_element(T)
|
| 105 |
+
b_T = _get_max_broadcast_value(G, U, v, values)
|
| 106 |
+
return b_T, _get_broadcast_centers(G, v, values, b_T)
|
| 107 |
+
|
| 108 |
+
|
| 109 |
+
@not_implemented_for("directed")
|
| 110 |
+
@not_implemented_for("multigraph")
|
| 111 |
+
@nx._dispatchable
|
| 112 |
+
def tree_broadcast_time(G, node=None):
|
| 113 |
+
"""Return the Broadcast Time of the tree `G`.
|
| 114 |
+
|
| 115 |
+
The minimum broadcast time of a node is defined as the minimum amount
|
| 116 |
+
of time required to complete broadcasting starting from the
|
| 117 |
+
originator. The broadcast time of a graph is the maximum over
|
| 118 |
+
all nodes of the minimum broadcast time from that node [1]_.
|
| 119 |
+
This function returns the minimum broadcast time of `node`.
|
| 120 |
+
If `node` is None the broadcast time for the graph is returned.
|
| 121 |
+
|
| 122 |
+
Parameters
|
| 123 |
+
----------
|
| 124 |
+
G : undirected graph
|
| 125 |
+
The graph should be an undirected tree
|
| 126 |
+
node: int, optional
|
| 127 |
+
index of starting node. If `None`, the algorithm returns the broadcast
|
| 128 |
+
time of the tree.
|
| 129 |
+
|
| 130 |
+
Returns
|
| 131 |
+
-------
|
| 132 |
+
BT : int
|
| 133 |
+
Broadcast Time of a node in a tree
|
| 134 |
+
|
| 135 |
+
Raises
|
| 136 |
+
------
|
| 137 |
+
NetworkXNotImplemented
|
| 138 |
+
If the graph is directed or is a multigraph.
|
| 139 |
+
|
| 140 |
+
References
|
| 141 |
+
----------
|
| 142 |
+
.. [1] Harutyunyan, H. A. and Li, Z.
|
| 143 |
+
"A Simple Construction of Broadcast Graphs."
|
| 144 |
+
In Computing and Combinatorics. COCOON 2019
|
| 145 |
+
(Ed. D. Z. Du and C. Tian.) Springer, pp. 240-253, 2019.
|
| 146 |
+
"""
|
| 147 |
+
b_T, b_C = tree_broadcast_center(G)
|
| 148 |
+
if node is not None:
|
| 149 |
+
return b_T + min(nx.shortest_path_length(G, node, u) for u in b_C)
|
| 150 |
+
dist_from_center = dict.fromkeys(G, len(G))
|
| 151 |
+
for u in b_C:
|
| 152 |
+
for v, dist in nx.shortest_path_length(G, u).items():
|
| 153 |
+
if dist < dist_from_center[v]:
|
| 154 |
+
dist_from_center[v] = dist
|
| 155 |
+
return b_T + max(dist_from_center.values())
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/chains.py
ADDED
|
@@ -0,0 +1,172 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for finding chains in a graph."""
|
| 2 |
+
|
| 3 |
+
import networkx as nx
|
| 4 |
+
from networkx.utils import not_implemented_for
|
| 5 |
+
|
| 6 |
+
__all__ = ["chain_decomposition"]
|
| 7 |
+
|
| 8 |
+
|
| 9 |
+
@not_implemented_for("directed")
|
| 10 |
+
@not_implemented_for("multigraph")
|
| 11 |
+
@nx._dispatchable
|
| 12 |
+
def chain_decomposition(G, root=None):
|
| 13 |
+
"""Returns the chain decomposition of a graph.
|
| 14 |
+
|
| 15 |
+
The *chain decomposition* of a graph with respect a depth-first
|
| 16 |
+
search tree is a set of cycles or paths derived from the set of
|
| 17 |
+
fundamental cycles of the tree in the following manner. Consider
|
| 18 |
+
each fundamental cycle with respect to the given tree, represented
|
| 19 |
+
as a list of edges beginning with the nontree edge oriented away
|
| 20 |
+
from the root of the tree. For each fundamental cycle, if it
|
| 21 |
+
overlaps with any previous fundamental cycle, just take the initial
|
| 22 |
+
non-overlapping segment, which is a path instead of a cycle. Each
|
| 23 |
+
cycle or path is called a *chain*. For more information, see [1]_.
|
| 24 |
+
|
| 25 |
+
Parameters
|
| 26 |
+
----------
|
| 27 |
+
G : undirected graph
|
| 28 |
+
|
| 29 |
+
root : node (optional)
|
| 30 |
+
A node in the graph `G`. If specified, only the chain
|
| 31 |
+
decomposition for the connected component containing this node
|
| 32 |
+
will be returned. This node indicates the root of the depth-first
|
| 33 |
+
search tree.
|
| 34 |
+
|
| 35 |
+
Yields
|
| 36 |
+
------
|
| 37 |
+
chain : list
|
| 38 |
+
A list of edges representing a chain. There is no guarantee on
|
| 39 |
+
the orientation of the edges in each chain (for example, if a
|
| 40 |
+
chain includes the edge joining nodes 1 and 2, the chain may
|
| 41 |
+
include either (1, 2) or (2, 1)).
|
| 42 |
+
|
| 43 |
+
Raises
|
| 44 |
+
------
|
| 45 |
+
NodeNotFound
|
| 46 |
+
If `root` is not in the graph `G`.
|
| 47 |
+
|
| 48 |
+
Examples
|
| 49 |
+
--------
|
| 50 |
+
>>> G = nx.Graph([(0, 1), (1, 4), (3, 4), (3, 5), (4, 5)])
|
| 51 |
+
>>> list(nx.chain_decomposition(G))
|
| 52 |
+
[[(4, 5), (5, 3), (3, 4)]]
|
| 53 |
+
|
| 54 |
+
Notes
|
| 55 |
+
-----
|
| 56 |
+
The worst-case running time of this implementation is linear in the
|
| 57 |
+
number of nodes and number of edges [1]_.
|
| 58 |
+
|
| 59 |
+
References
|
| 60 |
+
----------
|
| 61 |
+
.. [1] Jens M. Schmidt (2013). "A simple test on 2-vertex-
|
| 62 |
+
and 2-edge-connectivity." *Information Processing Letters*,
|
| 63 |
+
113, 241–244. Elsevier. <https://doi.org/10.1016/j.ipl.2013.01.016>
|
| 64 |
+
|
| 65 |
+
"""
|
| 66 |
+
|
| 67 |
+
def _dfs_cycle_forest(G, root=None):
|
| 68 |
+
"""Builds a directed graph composed of cycles from the given graph.
|
| 69 |
+
|
| 70 |
+
`G` is an undirected simple graph. `root` is a node in the graph
|
| 71 |
+
from which the depth-first search is started.
|
| 72 |
+
|
| 73 |
+
This function returns both the depth-first search cycle graph
|
| 74 |
+
(as a :class:`~networkx.DiGraph`) and the list of nodes in
|
| 75 |
+
depth-first preorder. The depth-first search cycle graph is a
|
| 76 |
+
directed graph whose edges are the edges of `G` oriented toward
|
| 77 |
+
the root if the edge is a tree edge and away from the root if
|
| 78 |
+
the edge is a non-tree edge. If `root` is not specified, this
|
| 79 |
+
performs a depth-first search on each connected component of `G`
|
| 80 |
+
and returns a directed forest instead.
|
| 81 |
+
|
| 82 |
+
If `root` is not in the graph, this raises :exc:`KeyError`.
|
| 83 |
+
|
| 84 |
+
"""
|
| 85 |
+
# Create a directed graph from the depth-first search tree with
|
| 86 |
+
# root node `root` in which tree edges are directed toward the
|
| 87 |
+
# root and nontree edges are directed away from the root. For
|
| 88 |
+
# each node with an incident nontree edge, this creates a
|
| 89 |
+
# directed cycle starting with the nontree edge and returning to
|
| 90 |
+
# that node.
|
| 91 |
+
#
|
| 92 |
+
# The `parent` node attribute stores the parent of each node in
|
| 93 |
+
# the DFS tree. The `nontree` edge attribute indicates whether
|
| 94 |
+
# the edge is a tree edge or a nontree edge.
|
| 95 |
+
#
|
| 96 |
+
# We also store the order of the nodes found in the depth-first
|
| 97 |
+
# search in the `nodes` list.
|
| 98 |
+
H = nx.DiGraph()
|
| 99 |
+
nodes = []
|
| 100 |
+
for u, v, d in nx.dfs_labeled_edges(G, source=root):
|
| 101 |
+
if d == "forward":
|
| 102 |
+
# `dfs_labeled_edges()` yields (root, root, 'forward')
|
| 103 |
+
# if it is beginning the search on a new connected
|
| 104 |
+
# component.
|
| 105 |
+
if u == v:
|
| 106 |
+
H.add_node(v, parent=None)
|
| 107 |
+
nodes.append(v)
|
| 108 |
+
else:
|
| 109 |
+
H.add_node(v, parent=u)
|
| 110 |
+
H.add_edge(v, u, nontree=False)
|
| 111 |
+
nodes.append(v)
|
| 112 |
+
# `dfs_labeled_edges` considers nontree edges in both
|
| 113 |
+
# orientations, so we need to not add the edge if it its
|
| 114 |
+
# other orientation has been added.
|
| 115 |
+
elif d == "nontree" and v not in H[u]:
|
| 116 |
+
H.add_edge(v, u, nontree=True)
|
| 117 |
+
else:
|
| 118 |
+
# Do nothing on 'reverse' edges; we only care about
|
| 119 |
+
# forward and nontree edges.
|
| 120 |
+
pass
|
| 121 |
+
return H, nodes
|
| 122 |
+
|
| 123 |
+
def _build_chain(G, u, v, visited):
|
| 124 |
+
"""Generate the chain starting from the given nontree edge.
|
| 125 |
+
|
| 126 |
+
`G` is a DFS cycle graph as constructed by
|
| 127 |
+
:func:`_dfs_cycle_graph`. The edge (`u`, `v`) is a nontree edge
|
| 128 |
+
that begins a chain. `visited` is a set representing the nodes
|
| 129 |
+
in `G` that have already been visited.
|
| 130 |
+
|
| 131 |
+
This function yields the edges in an initial segment of the
|
| 132 |
+
fundamental cycle of `G` starting with the nontree edge (`u`,
|
| 133 |
+
`v`) that includes all the edges up until the first node that
|
| 134 |
+
appears in `visited`. The tree edges are given by the 'parent'
|
| 135 |
+
node attribute. The `visited` set is updated to add each node in
|
| 136 |
+
an edge yielded by this function.
|
| 137 |
+
|
| 138 |
+
"""
|
| 139 |
+
while v not in visited:
|
| 140 |
+
yield u, v
|
| 141 |
+
visited.add(v)
|
| 142 |
+
u, v = v, G.nodes[v]["parent"]
|
| 143 |
+
yield u, v
|
| 144 |
+
|
| 145 |
+
# Check if the root is in the graph G. If not, raise NodeNotFound
|
| 146 |
+
if root is not None and root not in G:
|
| 147 |
+
raise nx.NodeNotFound(f"Root node {root} is not in graph")
|
| 148 |
+
|
| 149 |
+
# Create a directed version of H that has the DFS edges directed
|
| 150 |
+
# toward the root and the nontree edges directed away from the root
|
| 151 |
+
# (in each connected component).
|
| 152 |
+
H, nodes = _dfs_cycle_forest(G, root)
|
| 153 |
+
|
| 154 |
+
# Visit the nodes again in DFS order. For each node, and for each
|
| 155 |
+
# nontree edge leaving that node, compute the fundamental cycle for
|
| 156 |
+
# that nontree edge starting with that edge. If the fundamental
|
| 157 |
+
# cycle overlaps with any visited nodes, just take the prefix of the
|
| 158 |
+
# cycle up to the point of visited nodes.
|
| 159 |
+
#
|
| 160 |
+
# We repeat this process for each connected component (implicitly,
|
| 161 |
+
# since `nodes` already has a list of the nodes grouped by connected
|
| 162 |
+
# component).
|
| 163 |
+
visited = set()
|
| 164 |
+
for u in nodes:
|
| 165 |
+
visited.add(u)
|
| 166 |
+
# For each nontree edge going out of node u...
|
| 167 |
+
edges = ((u, v) for u, v, d in H.out_edges(u, data="nontree") if d)
|
| 168 |
+
for u, v in edges:
|
| 169 |
+
# Create the cycle or cycle prefix starting with the
|
| 170 |
+
# nontree edge.
|
| 171 |
+
chain = list(_build_chain(H, u, v, visited))
|
| 172 |
+
yield chain
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/chordal.py
ADDED
|
@@ -0,0 +1,443 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
Algorithms for chordal graphs.
|
| 3 |
+
|
| 4 |
+
A graph is chordal if every cycle of length at least 4 has a chord
|
| 5 |
+
(an edge joining two nodes not adjacent in the cycle).
|
| 6 |
+
https://en.wikipedia.org/wiki/Chordal_graph
|
| 7 |
+
"""
|
| 8 |
+
|
| 9 |
+
import sys
|
| 10 |
+
|
| 11 |
+
import networkx as nx
|
| 12 |
+
from networkx.algorithms.components import connected_components
|
| 13 |
+
from networkx.utils import arbitrary_element, not_implemented_for
|
| 14 |
+
|
| 15 |
+
__all__ = [
|
| 16 |
+
"is_chordal",
|
| 17 |
+
"find_induced_nodes",
|
| 18 |
+
"chordal_graph_cliques",
|
| 19 |
+
"chordal_graph_treewidth",
|
| 20 |
+
"NetworkXTreewidthBoundExceeded",
|
| 21 |
+
"complete_to_chordal_graph",
|
| 22 |
+
]
|
| 23 |
+
|
| 24 |
+
|
| 25 |
+
class NetworkXTreewidthBoundExceeded(nx.NetworkXException):
|
| 26 |
+
"""Exception raised when a treewidth bound has been provided and it has
|
| 27 |
+
been exceeded"""
|
| 28 |
+
|
| 29 |
+
|
| 30 |
+
@not_implemented_for("directed")
|
| 31 |
+
@not_implemented_for("multigraph")
|
| 32 |
+
@nx._dispatchable
|
| 33 |
+
def is_chordal(G):
|
| 34 |
+
"""Checks whether G is a chordal graph.
|
| 35 |
+
|
| 36 |
+
A graph is chordal if every cycle of length at least 4 has a chord
|
| 37 |
+
(an edge joining two nodes not adjacent in the cycle).
|
| 38 |
+
|
| 39 |
+
Parameters
|
| 40 |
+
----------
|
| 41 |
+
G : graph
|
| 42 |
+
A NetworkX graph.
|
| 43 |
+
|
| 44 |
+
Returns
|
| 45 |
+
-------
|
| 46 |
+
chordal : bool
|
| 47 |
+
True if G is a chordal graph and False otherwise.
|
| 48 |
+
|
| 49 |
+
Raises
|
| 50 |
+
------
|
| 51 |
+
NetworkXNotImplemented
|
| 52 |
+
The algorithm does not support DiGraph, MultiGraph and MultiDiGraph.
|
| 53 |
+
|
| 54 |
+
Examples
|
| 55 |
+
--------
|
| 56 |
+
>>> e = [
|
| 57 |
+
... (1, 2),
|
| 58 |
+
... (1, 3),
|
| 59 |
+
... (2, 3),
|
| 60 |
+
... (2, 4),
|
| 61 |
+
... (3, 4),
|
| 62 |
+
... (3, 5),
|
| 63 |
+
... (3, 6),
|
| 64 |
+
... (4, 5),
|
| 65 |
+
... (4, 6),
|
| 66 |
+
... (5, 6),
|
| 67 |
+
... ]
|
| 68 |
+
>>> G = nx.Graph(e)
|
| 69 |
+
>>> nx.is_chordal(G)
|
| 70 |
+
True
|
| 71 |
+
|
| 72 |
+
Notes
|
| 73 |
+
-----
|
| 74 |
+
The routine tries to go through every node following maximum cardinality
|
| 75 |
+
search. It returns False when it finds that the separator for any node
|
| 76 |
+
is not a clique. Based on the algorithms in [1]_.
|
| 77 |
+
|
| 78 |
+
Self loops are ignored.
|
| 79 |
+
|
| 80 |
+
References
|
| 81 |
+
----------
|
| 82 |
+
.. [1] R. E. Tarjan and M. Yannakakis, Simple linear-time algorithms
|
| 83 |
+
to test chordality of graphs, test acyclicity of hypergraphs, and
|
| 84 |
+
selectively reduce acyclic hypergraphs, SIAM J. Comput., 13 (1984),
|
| 85 |
+
pp. 566–579.
|
| 86 |
+
"""
|
| 87 |
+
if len(G.nodes) <= 3:
|
| 88 |
+
return True
|
| 89 |
+
return len(_find_chordality_breaker(G)) == 0
|
| 90 |
+
|
| 91 |
+
|
| 92 |
+
@nx._dispatchable
|
| 93 |
+
def find_induced_nodes(G, s, t, treewidth_bound=sys.maxsize):
|
| 94 |
+
"""Returns the set of induced nodes in the path from s to t.
|
| 95 |
+
|
| 96 |
+
Parameters
|
| 97 |
+
----------
|
| 98 |
+
G : graph
|
| 99 |
+
A chordal NetworkX graph
|
| 100 |
+
s : node
|
| 101 |
+
Source node to look for induced nodes
|
| 102 |
+
t : node
|
| 103 |
+
Destination node to look for induced nodes
|
| 104 |
+
treewidth_bound: float
|
| 105 |
+
Maximum treewidth acceptable for the graph H. The search
|
| 106 |
+
for induced nodes will end as soon as the treewidth_bound is exceeded.
|
| 107 |
+
|
| 108 |
+
Returns
|
| 109 |
+
-------
|
| 110 |
+
induced_nodes : Set of nodes
|
| 111 |
+
The set of induced nodes in the path from s to t in G
|
| 112 |
+
|
| 113 |
+
Raises
|
| 114 |
+
------
|
| 115 |
+
NetworkXError
|
| 116 |
+
The algorithm does not support DiGraph, MultiGraph and MultiDiGraph.
|
| 117 |
+
If the input graph is an instance of one of these classes, a
|
| 118 |
+
:exc:`NetworkXError` is raised.
|
| 119 |
+
The algorithm can only be applied to chordal graphs. If the input
|
| 120 |
+
graph is found to be non-chordal, a :exc:`NetworkXError` is raised.
|
| 121 |
+
|
| 122 |
+
Examples
|
| 123 |
+
--------
|
| 124 |
+
>>> G = nx.Graph()
|
| 125 |
+
>>> G = nx.generators.classic.path_graph(10)
|
| 126 |
+
>>> induced_nodes = nx.find_induced_nodes(G, 1, 9, 2)
|
| 127 |
+
>>> sorted(induced_nodes)
|
| 128 |
+
[1, 2, 3, 4, 5, 6, 7, 8, 9]
|
| 129 |
+
|
| 130 |
+
Notes
|
| 131 |
+
-----
|
| 132 |
+
G must be a chordal graph and (s,t) an edge that is not in G.
|
| 133 |
+
|
| 134 |
+
If a treewidth_bound is provided, the search for induced nodes will end
|
| 135 |
+
as soon as the treewidth_bound is exceeded.
|
| 136 |
+
|
| 137 |
+
The algorithm is inspired by Algorithm 4 in [1]_.
|
| 138 |
+
A formal definition of induced node can also be found on that reference.
|
| 139 |
+
|
| 140 |
+
Self Loops are ignored
|
| 141 |
+
|
| 142 |
+
References
|
| 143 |
+
----------
|
| 144 |
+
.. [1] Learning Bounded Treewidth Bayesian Networks.
|
| 145 |
+
Gal Elidan, Stephen Gould; JMLR, 9(Dec):2699--2731, 2008.
|
| 146 |
+
http://jmlr.csail.mit.edu/papers/volume9/elidan08a/elidan08a.pdf
|
| 147 |
+
"""
|
| 148 |
+
if not is_chordal(G):
|
| 149 |
+
raise nx.NetworkXError("Input graph is not chordal.")
|
| 150 |
+
|
| 151 |
+
H = nx.Graph(G)
|
| 152 |
+
H.add_edge(s, t)
|
| 153 |
+
induced_nodes = set()
|
| 154 |
+
triplet = _find_chordality_breaker(H, s, treewidth_bound)
|
| 155 |
+
while triplet:
|
| 156 |
+
(u, v, w) = triplet
|
| 157 |
+
induced_nodes.update(triplet)
|
| 158 |
+
for n in triplet:
|
| 159 |
+
if n != s:
|
| 160 |
+
H.add_edge(s, n)
|
| 161 |
+
triplet = _find_chordality_breaker(H, s, treewidth_bound)
|
| 162 |
+
if induced_nodes:
|
| 163 |
+
# Add t and the second node in the induced path from s to t.
|
| 164 |
+
induced_nodes.add(t)
|
| 165 |
+
for u in G[s]:
|
| 166 |
+
if len(induced_nodes & set(G[u])) == 2:
|
| 167 |
+
induced_nodes.add(u)
|
| 168 |
+
break
|
| 169 |
+
return induced_nodes
|
| 170 |
+
|
| 171 |
+
|
| 172 |
+
@nx._dispatchable
|
| 173 |
+
def chordal_graph_cliques(G):
|
| 174 |
+
"""Returns all maximal cliques of a chordal graph.
|
| 175 |
+
|
| 176 |
+
The algorithm breaks the graph in connected components and performs a
|
| 177 |
+
maximum cardinality search in each component to get the cliques.
|
| 178 |
+
|
| 179 |
+
Parameters
|
| 180 |
+
----------
|
| 181 |
+
G : graph
|
| 182 |
+
A NetworkX graph
|
| 183 |
+
|
| 184 |
+
Yields
|
| 185 |
+
------
|
| 186 |
+
frozenset of nodes
|
| 187 |
+
Maximal cliques, each of which is a frozenset of
|
| 188 |
+
nodes in `G`. The order of cliques is arbitrary.
|
| 189 |
+
|
| 190 |
+
Raises
|
| 191 |
+
------
|
| 192 |
+
NetworkXError
|
| 193 |
+
The algorithm does not support DiGraph, MultiGraph and MultiDiGraph.
|
| 194 |
+
The algorithm can only be applied to chordal graphs. If the input
|
| 195 |
+
graph is found to be non-chordal, a :exc:`NetworkXError` is raised.
|
| 196 |
+
|
| 197 |
+
Examples
|
| 198 |
+
--------
|
| 199 |
+
>>> e = [
|
| 200 |
+
... (1, 2),
|
| 201 |
+
... (1, 3),
|
| 202 |
+
... (2, 3),
|
| 203 |
+
... (2, 4),
|
| 204 |
+
... (3, 4),
|
| 205 |
+
... (3, 5),
|
| 206 |
+
... (3, 6),
|
| 207 |
+
... (4, 5),
|
| 208 |
+
... (4, 6),
|
| 209 |
+
... (5, 6),
|
| 210 |
+
... (7, 8),
|
| 211 |
+
... ]
|
| 212 |
+
>>> G = nx.Graph(e)
|
| 213 |
+
>>> G.add_node(9)
|
| 214 |
+
>>> cliques = [c for c in chordal_graph_cliques(G)]
|
| 215 |
+
>>> cliques[0]
|
| 216 |
+
frozenset({1, 2, 3})
|
| 217 |
+
"""
|
| 218 |
+
for C in (G.subgraph(c).copy() for c in connected_components(G)):
|
| 219 |
+
if C.number_of_nodes() == 1:
|
| 220 |
+
if nx.number_of_selfloops(C) > 0:
|
| 221 |
+
raise nx.NetworkXError("Input graph is not chordal.")
|
| 222 |
+
yield frozenset(C.nodes())
|
| 223 |
+
else:
|
| 224 |
+
unnumbered = set(C.nodes())
|
| 225 |
+
v = arbitrary_element(C)
|
| 226 |
+
unnumbered.remove(v)
|
| 227 |
+
numbered = {v}
|
| 228 |
+
clique_wanna_be = {v}
|
| 229 |
+
while unnumbered:
|
| 230 |
+
v = _max_cardinality_node(C, unnumbered, numbered)
|
| 231 |
+
unnumbered.remove(v)
|
| 232 |
+
numbered.add(v)
|
| 233 |
+
new_clique_wanna_be = set(C.neighbors(v)) & numbered
|
| 234 |
+
sg = C.subgraph(clique_wanna_be)
|
| 235 |
+
if _is_complete_graph(sg):
|
| 236 |
+
new_clique_wanna_be.add(v)
|
| 237 |
+
if not new_clique_wanna_be >= clique_wanna_be:
|
| 238 |
+
yield frozenset(clique_wanna_be)
|
| 239 |
+
clique_wanna_be = new_clique_wanna_be
|
| 240 |
+
else:
|
| 241 |
+
raise nx.NetworkXError("Input graph is not chordal.")
|
| 242 |
+
yield frozenset(clique_wanna_be)
|
| 243 |
+
|
| 244 |
+
|
| 245 |
+
@nx._dispatchable
|
| 246 |
+
def chordal_graph_treewidth(G):
|
| 247 |
+
"""Returns the treewidth of the chordal graph G.
|
| 248 |
+
|
| 249 |
+
Parameters
|
| 250 |
+
----------
|
| 251 |
+
G : graph
|
| 252 |
+
A NetworkX graph
|
| 253 |
+
|
| 254 |
+
Returns
|
| 255 |
+
-------
|
| 256 |
+
treewidth : int
|
| 257 |
+
The size of the largest clique in the graph minus one.
|
| 258 |
+
|
| 259 |
+
Raises
|
| 260 |
+
------
|
| 261 |
+
NetworkXError
|
| 262 |
+
The algorithm does not support DiGraph, MultiGraph and MultiDiGraph.
|
| 263 |
+
The algorithm can only be applied to chordal graphs. If the input
|
| 264 |
+
graph is found to be non-chordal, a :exc:`NetworkXError` is raised.
|
| 265 |
+
|
| 266 |
+
Examples
|
| 267 |
+
--------
|
| 268 |
+
>>> e = [
|
| 269 |
+
... (1, 2),
|
| 270 |
+
... (1, 3),
|
| 271 |
+
... (2, 3),
|
| 272 |
+
... (2, 4),
|
| 273 |
+
... (3, 4),
|
| 274 |
+
... (3, 5),
|
| 275 |
+
... (3, 6),
|
| 276 |
+
... (4, 5),
|
| 277 |
+
... (4, 6),
|
| 278 |
+
... (5, 6),
|
| 279 |
+
... (7, 8),
|
| 280 |
+
... ]
|
| 281 |
+
>>> G = nx.Graph(e)
|
| 282 |
+
>>> G.add_node(9)
|
| 283 |
+
>>> nx.chordal_graph_treewidth(G)
|
| 284 |
+
3
|
| 285 |
+
|
| 286 |
+
References
|
| 287 |
+
----------
|
| 288 |
+
.. [1] https://en.wikipedia.org/wiki/Tree_decomposition#Treewidth
|
| 289 |
+
"""
|
| 290 |
+
if not is_chordal(G):
|
| 291 |
+
raise nx.NetworkXError("Input graph is not chordal.")
|
| 292 |
+
|
| 293 |
+
max_clique = -1
|
| 294 |
+
for clique in nx.chordal_graph_cliques(G):
|
| 295 |
+
max_clique = max(max_clique, len(clique))
|
| 296 |
+
return max_clique - 1
|
| 297 |
+
|
| 298 |
+
|
| 299 |
+
def _is_complete_graph(G):
|
| 300 |
+
"""Returns True if G is a complete graph."""
|
| 301 |
+
if nx.number_of_selfloops(G) > 0:
|
| 302 |
+
raise nx.NetworkXError("Self loop found in _is_complete_graph()")
|
| 303 |
+
n = G.number_of_nodes()
|
| 304 |
+
if n < 2:
|
| 305 |
+
return True
|
| 306 |
+
e = G.number_of_edges()
|
| 307 |
+
max_edges = (n * (n - 1)) / 2
|
| 308 |
+
return e == max_edges
|
| 309 |
+
|
| 310 |
+
|
| 311 |
+
def _find_missing_edge(G):
|
| 312 |
+
"""Given a non-complete graph G, returns a missing edge."""
|
| 313 |
+
nodes = set(G)
|
| 314 |
+
for u in G:
|
| 315 |
+
missing = nodes - set(list(G[u].keys()) + [u])
|
| 316 |
+
if missing:
|
| 317 |
+
return (u, missing.pop())
|
| 318 |
+
|
| 319 |
+
|
| 320 |
+
def _max_cardinality_node(G, choices, wanna_connect):
|
| 321 |
+
"""Returns a the node in choices that has more connections in G
|
| 322 |
+
to nodes in wanna_connect.
|
| 323 |
+
"""
|
| 324 |
+
max_number = -1
|
| 325 |
+
for x in choices:
|
| 326 |
+
number = len([y for y in G[x] if y in wanna_connect])
|
| 327 |
+
if number > max_number:
|
| 328 |
+
max_number = number
|
| 329 |
+
max_cardinality_node = x
|
| 330 |
+
return max_cardinality_node
|
| 331 |
+
|
| 332 |
+
|
| 333 |
+
def _find_chordality_breaker(G, s=None, treewidth_bound=sys.maxsize):
|
| 334 |
+
"""Given a graph G, starts a max cardinality search
|
| 335 |
+
(starting from s if s is given and from an arbitrary node otherwise)
|
| 336 |
+
trying to find a non-chordal cycle.
|
| 337 |
+
|
| 338 |
+
If it does find one, it returns (u,v,w) where u,v,w are the three
|
| 339 |
+
nodes that together with s are involved in the cycle.
|
| 340 |
+
|
| 341 |
+
It ignores any self loops.
|
| 342 |
+
"""
|
| 343 |
+
if len(G) == 0:
|
| 344 |
+
raise nx.NetworkXPointlessConcept("Graph has no nodes.")
|
| 345 |
+
unnumbered = set(G)
|
| 346 |
+
if s is None:
|
| 347 |
+
s = arbitrary_element(G)
|
| 348 |
+
unnumbered.remove(s)
|
| 349 |
+
numbered = {s}
|
| 350 |
+
current_treewidth = -1
|
| 351 |
+
while unnumbered: # and current_treewidth <= treewidth_bound:
|
| 352 |
+
v = _max_cardinality_node(G, unnumbered, numbered)
|
| 353 |
+
unnumbered.remove(v)
|
| 354 |
+
numbered.add(v)
|
| 355 |
+
clique_wanna_be = set(G[v]) & numbered
|
| 356 |
+
sg = G.subgraph(clique_wanna_be)
|
| 357 |
+
if _is_complete_graph(sg):
|
| 358 |
+
# The graph seems to be chordal by now. We update the treewidth
|
| 359 |
+
current_treewidth = max(current_treewidth, len(clique_wanna_be))
|
| 360 |
+
if current_treewidth > treewidth_bound:
|
| 361 |
+
raise nx.NetworkXTreewidthBoundExceeded(
|
| 362 |
+
f"treewidth_bound exceeded: {current_treewidth}"
|
| 363 |
+
)
|
| 364 |
+
else:
|
| 365 |
+
# sg is not a clique,
|
| 366 |
+
# look for an edge that is not included in sg
|
| 367 |
+
(u, w) = _find_missing_edge(sg)
|
| 368 |
+
return (u, v, w)
|
| 369 |
+
return ()
|
| 370 |
+
|
| 371 |
+
|
| 372 |
+
@not_implemented_for("directed")
|
| 373 |
+
@nx._dispatchable(returns_graph=True)
|
| 374 |
+
def complete_to_chordal_graph(G):
|
| 375 |
+
"""Return a copy of G completed to a chordal graph
|
| 376 |
+
|
| 377 |
+
Adds edges to a copy of G to create a chordal graph. A graph G=(V,E) is
|
| 378 |
+
called chordal if for each cycle with length bigger than 3, there exist
|
| 379 |
+
two non-adjacent nodes connected by an edge (called a chord).
|
| 380 |
+
|
| 381 |
+
Parameters
|
| 382 |
+
----------
|
| 383 |
+
G : NetworkX graph
|
| 384 |
+
Undirected graph
|
| 385 |
+
|
| 386 |
+
Returns
|
| 387 |
+
-------
|
| 388 |
+
H : NetworkX graph
|
| 389 |
+
The chordal enhancement of G
|
| 390 |
+
alpha : Dictionary
|
| 391 |
+
The elimination ordering of nodes of G
|
| 392 |
+
|
| 393 |
+
Notes
|
| 394 |
+
-----
|
| 395 |
+
There are different approaches to calculate the chordal
|
| 396 |
+
enhancement of a graph. The algorithm used here is called
|
| 397 |
+
MCS-M and gives at least minimal (local) triangulation of graph. Note
|
| 398 |
+
that this triangulation is not necessarily a global minimum.
|
| 399 |
+
|
| 400 |
+
https://en.wikipedia.org/wiki/Chordal_graph
|
| 401 |
+
|
| 402 |
+
References
|
| 403 |
+
----------
|
| 404 |
+
.. [1] Berry, Anne & Blair, Jean & Heggernes, Pinar & Peyton, Barry. (2004)
|
| 405 |
+
Maximum Cardinality Search for Computing Minimal Triangulations of
|
| 406 |
+
Graphs. Algorithmica. 39. 287-298. 10.1007/s00453-004-1084-3.
|
| 407 |
+
|
| 408 |
+
Examples
|
| 409 |
+
--------
|
| 410 |
+
>>> from networkx.algorithms.chordal import complete_to_chordal_graph
|
| 411 |
+
>>> G = nx.wheel_graph(10)
|
| 412 |
+
>>> H, alpha = complete_to_chordal_graph(G)
|
| 413 |
+
"""
|
| 414 |
+
H = G.copy()
|
| 415 |
+
alpha = dict.fromkeys(H, 0)
|
| 416 |
+
if nx.is_chordal(H):
|
| 417 |
+
return H, alpha
|
| 418 |
+
chords = set()
|
| 419 |
+
weight = dict.fromkeys(H.nodes(), 0)
|
| 420 |
+
unnumbered_nodes = list(H.nodes())
|
| 421 |
+
for i in range(len(H.nodes()), 0, -1):
|
| 422 |
+
# get the node in unnumbered_nodes with the maximum weight
|
| 423 |
+
z = max(unnumbered_nodes, key=lambda node: weight[node])
|
| 424 |
+
unnumbered_nodes.remove(z)
|
| 425 |
+
alpha[z] = i
|
| 426 |
+
update_nodes = []
|
| 427 |
+
for y in unnumbered_nodes:
|
| 428 |
+
if G.has_edge(y, z):
|
| 429 |
+
update_nodes.append(y)
|
| 430 |
+
else:
|
| 431 |
+
# y_weight will be bigger than node weights between y and z
|
| 432 |
+
y_weight = weight[y]
|
| 433 |
+
lower_nodes = [
|
| 434 |
+
node for node in unnumbered_nodes if weight[node] < y_weight
|
| 435 |
+
]
|
| 436 |
+
if nx.has_path(H.subgraph(lower_nodes + [z, y]), y, z):
|
| 437 |
+
update_nodes.append(y)
|
| 438 |
+
chords.add((z, y))
|
| 439 |
+
# during calculation of paths the weights should not be updated
|
| 440 |
+
for node in update_nodes:
|
| 441 |
+
weight[node] += 1
|
| 442 |
+
H.add_edges_from(chords)
|
| 443 |
+
return H, alpha
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/clique.py
ADDED
|
@@ -0,0 +1,757 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for finding and manipulating cliques.
|
| 2 |
+
|
| 3 |
+
Finding the largest clique in a graph is NP-complete problem, so most of
|
| 4 |
+
these algorithms have an exponential running time; for more information,
|
| 5 |
+
see the Wikipedia article on the clique problem [1]_.
|
| 6 |
+
|
| 7 |
+
.. [1] clique problem:: https://en.wikipedia.org/wiki/Clique_problem
|
| 8 |
+
|
| 9 |
+
"""
|
| 10 |
+
|
| 11 |
+
from collections import Counter, defaultdict, deque
|
| 12 |
+
from itertools import chain, combinations, islice
|
| 13 |
+
|
| 14 |
+
import networkx as nx
|
| 15 |
+
from networkx.utils import not_implemented_for
|
| 16 |
+
|
| 17 |
+
__all__ = [
|
| 18 |
+
"find_cliques",
|
| 19 |
+
"find_cliques_recursive",
|
| 20 |
+
"make_max_clique_graph",
|
| 21 |
+
"make_clique_bipartite",
|
| 22 |
+
"node_clique_number",
|
| 23 |
+
"number_of_cliques",
|
| 24 |
+
"enumerate_all_cliques",
|
| 25 |
+
"max_weight_clique",
|
| 26 |
+
]
|
| 27 |
+
|
| 28 |
+
|
| 29 |
+
@not_implemented_for("directed")
|
| 30 |
+
@nx._dispatchable
|
| 31 |
+
def enumerate_all_cliques(G):
|
| 32 |
+
"""Returns all cliques in an undirected graph.
|
| 33 |
+
|
| 34 |
+
This function returns an iterator over cliques, each of which is a
|
| 35 |
+
list of nodes. The iteration is ordered by cardinality of the
|
| 36 |
+
cliques: first all cliques of size one, then all cliques of size
|
| 37 |
+
two, etc.
|
| 38 |
+
|
| 39 |
+
Parameters
|
| 40 |
+
----------
|
| 41 |
+
G : NetworkX graph
|
| 42 |
+
An undirected graph.
|
| 43 |
+
|
| 44 |
+
Returns
|
| 45 |
+
-------
|
| 46 |
+
iterator
|
| 47 |
+
An iterator over cliques, each of which is a list of nodes in
|
| 48 |
+
`G`. The cliques are ordered according to size.
|
| 49 |
+
|
| 50 |
+
Notes
|
| 51 |
+
-----
|
| 52 |
+
To obtain a list of all cliques, use
|
| 53 |
+
`list(enumerate_all_cliques(G))`. However, be aware that in the
|
| 54 |
+
worst-case, the length of this list can be exponential in the number
|
| 55 |
+
of nodes in the graph (for example, when the graph is the complete
|
| 56 |
+
graph). This function avoids storing all cliques in memory by only
|
| 57 |
+
keeping current candidate node lists in memory during its search.
|
| 58 |
+
|
| 59 |
+
The implementation is adapted from the algorithm by Zhang, et
|
| 60 |
+
al. (2005) [1]_ to output all cliques discovered.
|
| 61 |
+
|
| 62 |
+
This algorithm ignores self-loops and parallel edges, since cliques
|
| 63 |
+
are not conventionally defined with such edges.
|
| 64 |
+
|
| 65 |
+
References
|
| 66 |
+
----------
|
| 67 |
+
.. [1] Yun Zhang, Abu-Khzam, F.N., Baldwin, N.E., Chesler, E.J.,
|
| 68 |
+
Langston, M.A., Samatova, N.F.,
|
| 69 |
+
"Genome-Scale Computational Approaches to Memory-Intensive
|
| 70 |
+
Applications in Systems Biology".
|
| 71 |
+
*Supercomputing*, 2005. Proceedings of the ACM/IEEE SC 2005
|
| 72 |
+
Conference, pp. 12, 12--18 Nov. 2005.
|
| 73 |
+
<https://doi.org/10.1109/SC.2005.29>.
|
| 74 |
+
|
| 75 |
+
"""
|
| 76 |
+
index = {}
|
| 77 |
+
nbrs = {}
|
| 78 |
+
for u in G:
|
| 79 |
+
index[u] = len(index)
|
| 80 |
+
# Neighbors of u that appear after u in the iteration order of G.
|
| 81 |
+
nbrs[u] = {v for v in G[u] if v not in index}
|
| 82 |
+
|
| 83 |
+
queue = deque(([u], sorted(nbrs[u], key=index.__getitem__)) for u in G)
|
| 84 |
+
# Loop invariants:
|
| 85 |
+
# 1. len(base) is nondecreasing.
|
| 86 |
+
# 2. (base + cnbrs) is sorted with respect to the iteration order of G.
|
| 87 |
+
# 3. cnbrs is a set of common neighbors of nodes in base.
|
| 88 |
+
while queue:
|
| 89 |
+
base, cnbrs = map(list, queue.popleft())
|
| 90 |
+
yield base
|
| 91 |
+
for i, u in enumerate(cnbrs):
|
| 92 |
+
# Use generators to reduce memory consumption.
|
| 93 |
+
queue.append(
|
| 94 |
+
(
|
| 95 |
+
chain(base, [u]),
|
| 96 |
+
filter(nbrs[u].__contains__, islice(cnbrs, i + 1, None)),
|
| 97 |
+
)
|
| 98 |
+
)
|
| 99 |
+
|
| 100 |
+
|
| 101 |
+
@not_implemented_for("directed")
|
| 102 |
+
@nx._dispatchable
|
| 103 |
+
def find_cliques(G, nodes=None):
|
| 104 |
+
"""Returns all maximal cliques in an undirected graph.
|
| 105 |
+
|
| 106 |
+
For each node *n*, a *maximal clique for n* is a largest complete
|
| 107 |
+
subgraph containing *n*. The largest maximal clique is sometimes
|
| 108 |
+
called the *maximum clique*.
|
| 109 |
+
|
| 110 |
+
This function returns an iterator over cliques, each of which is a
|
| 111 |
+
list of nodes. It is an iterative implementation, so should not
|
| 112 |
+
suffer from recursion depth issues.
|
| 113 |
+
|
| 114 |
+
This function accepts a list of `nodes` and only the maximal cliques
|
| 115 |
+
containing all of these `nodes` are returned. It can considerably speed up
|
| 116 |
+
the running time if some specific cliques are desired.
|
| 117 |
+
|
| 118 |
+
Parameters
|
| 119 |
+
----------
|
| 120 |
+
G : NetworkX graph
|
| 121 |
+
An undirected graph.
|
| 122 |
+
|
| 123 |
+
nodes : list, optional (default=None)
|
| 124 |
+
If provided, only yield *maximal cliques* containing all nodes in `nodes`.
|
| 125 |
+
If `nodes` isn't a clique itself, a ValueError is raised.
|
| 126 |
+
|
| 127 |
+
Returns
|
| 128 |
+
-------
|
| 129 |
+
iterator
|
| 130 |
+
An iterator over maximal cliques, each of which is a list of
|
| 131 |
+
nodes in `G`. If `nodes` is provided, only the maximal cliques
|
| 132 |
+
containing all the nodes in `nodes` are returned. The order of
|
| 133 |
+
cliques is arbitrary.
|
| 134 |
+
|
| 135 |
+
Raises
|
| 136 |
+
------
|
| 137 |
+
ValueError
|
| 138 |
+
If `nodes` is not a clique.
|
| 139 |
+
|
| 140 |
+
Examples
|
| 141 |
+
--------
|
| 142 |
+
>>> from pprint import pprint # For nice dict formatting
|
| 143 |
+
>>> G = nx.karate_club_graph()
|
| 144 |
+
>>> sum(1 for c in nx.find_cliques(G)) # The number of maximal cliques in G
|
| 145 |
+
36
|
| 146 |
+
>>> max(nx.find_cliques(G), key=len) # The largest maximal clique in G
|
| 147 |
+
[0, 1, 2, 3, 13]
|
| 148 |
+
|
| 149 |
+
The size of the largest maximal clique is known as the *clique number* of
|
| 150 |
+
the graph, which can be found directly with:
|
| 151 |
+
|
| 152 |
+
>>> max(len(c) for c in nx.find_cliques(G))
|
| 153 |
+
5
|
| 154 |
+
|
| 155 |
+
One can also compute the number of maximal cliques in `G` that contain a given
|
| 156 |
+
node. The following produces a dictionary keyed by node whose
|
| 157 |
+
values are the number of maximal cliques in `G` that contain the node:
|
| 158 |
+
|
| 159 |
+
>>> from collections import Counter
|
| 160 |
+
>>> from itertools import chain
|
| 161 |
+
>>> counts = Counter(chain.from_iterable(nx.find_cliques(G)))
|
| 162 |
+
>>> pprint(dict(counts))
|
| 163 |
+
{0: 13,
|
| 164 |
+
1: 6,
|
| 165 |
+
2: 7,
|
| 166 |
+
3: 3,
|
| 167 |
+
4: 2,
|
| 168 |
+
5: 3,
|
| 169 |
+
6: 3,
|
| 170 |
+
7: 1,
|
| 171 |
+
8: 3,
|
| 172 |
+
9: 2,
|
| 173 |
+
10: 2,
|
| 174 |
+
11: 1,
|
| 175 |
+
12: 1,
|
| 176 |
+
13: 2,
|
| 177 |
+
14: 1,
|
| 178 |
+
15: 1,
|
| 179 |
+
16: 1,
|
| 180 |
+
17: 1,
|
| 181 |
+
18: 1,
|
| 182 |
+
19: 2,
|
| 183 |
+
20: 1,
|
| 184 |
+
21: 1,
|
| 185 |
+
22: 1,
|
| 186 |
+
23: 3,
|
| 187 |
+
24: 2,
|
| 188 |
+
25: 2,
|
| 189 |
+
26: 1,
|
| 190 |
+
27: 3,
|
| 191 |
+
28: 2,
|
| 192 |
+
29: 2,
|
| 193 |
+
30: 2,
|
| 194 |
+
31: 4,
|
| 195 |
+
32: 9,
|
| 196 |
+
33: 14}
|
| 197 |
+
|
| 198 |
+
Or, similarly, the maximal cliques in `G` that contain a given node.
|
| 199 |
+
For example, the 4 maximal cliques that contain node 31:
|
| 200 |
+
|
| 201 |
+
>>> [c for c in nx.find_cliques(G) if 31 in c]
|
| 202 |
+
[[0, 31], [33, 32, 31], [33, 28, 31], [24, 25, 31]]
|
| 203 |
+
|
| 204 |
+
See Also
|
| 205 |
+
--------
|
| 206 |
+
find_cliques_recursive
|
| 207 |
+
A recursive version of the same algorithm.
|
| 208 |
+
|
| 209 |
+
Notes
|
| 210 |
+
-----
|
| 211 |
+
To obtain a list of all maximal cliques, use
|
| 212 |
+
`list(find_cliques(G))`. However, be aware that in the worst-case,
|
| 213 |
+
the length of this list can be exponential in the number of nodes in
|
| 214 |
+
the graph. This function avoids storing all cliques in memory by
|
| 215 |
+
only keeping current candidate node lists in memory during its search.
|
| 216 |
+
|
| 217 |
+
This implementation is based on the algorithm published by Bron and
|
| 218 |
+
Kerbosch (1973) [1]_, as adapted by Tomita, Tanaka and Takahashi
|
| 219 |
+
(2006) [2]_ and discussed in Cazals and Karande (2008) [3]_. It
|
| 220 |
+
essentially unrolls the recursion used in the references to avoid
|
| 221 |
+
issues of recursion stack depth (for a recursive implementation, see
|
| 222 |
+
:func:`find_cliques_recursive`).
|
| 223 |
+
|
| 224 |
+
This algorithm ignores self-loops and parallel edges, since cliques
|
| 225 |
+
are not conventionally defined with such edges.
|
| 226 |
+
|
| 227 |
+
References
|
| 228 |
+
----------
|
| 229 |
+
.. [1] Bron, C. and Kerbosch, J.
|
| 230 |
+
"Algorithm 457: finding all cliques of an undirected graph".
|
| 231 |
+
*Communications of the ACM* 16, 9 (Sep. 1973), 575--577.
|
| 232 |
+
<http://portal.acm.org/citation.cfm?doid=362342.362367>
|
| 233 |
+
|
| 234 |
+
.. [2] Etsuji Tomita, Akira Tanaka, Haruhisa Takahashi,
|
| 235 |
+
"The worst-case time complexity for generating all maximal
|
| 236 |
+
cliques and computational experiments",
|
| 237 |
+
*Theoretical Computer Science*, Volume 363, Issue 1,
|
| 238 |
+
Computing and Combinatorics,
|
| 239 |
+
10th Annual International Conference on
|
| 240 |
+
Computing and Combinatorics (COCOON 2004), 25 October 2006, Pages 28--42
|
| 241 |
+
<https://doi.org/10.1016/j.tcs.2006.06.015>
|
| 242 |
+
|
| 243 |
+
.. [3] F. Cazals, C. Karande,
|
| 244 |
+
"A note on the problem of reporting maximal cliques",
|
| 245 |
+
*Theoretical Computer Science*,
|
| 246 |
+
Volume 407, Issues 1--3, 6 November 2008, Pages 564--568,
|
| 247 |
+
<https://doi.org/10.1016/j.tcs.2008.05.010>
|
| 248 |
+
|
| 249 |
+
"""
|
| 250 |
+
if len(G) == 0:
|
| 251 |
+
return
|
| 252 |
+
|
| 253 |
+
adj = {u: {v for v in G[u] if v != u} for u in G}
|
| 254 |
+
|
| 255 |
+
# Initialize Q with the given nodes and subg, cand with their nbrs
|
| 256 |
+
Q = nodes[:] if nodes is not None else []
|
| 257 |
+
cand = set(G)
|
| 258 |
+
for node in Q:
|
| 259 |
+
if node not in cand:
|
| 260 |
+
raise ValueError(f"The given `nodes` {nodes} do not form a clique")
|
| 261 |
+
cand &= adj[node]
|
| 262 |
+
|
| 263 |
+
if not cand:
|
| 264 |
+
yield Q[:]
|
| 265 |
+
return
|
| 266 |
+
|
| 267 |
+
subg = cand.copy()
|
| 268 |
+
stack = []
|
| 269 |
+
Q.append(None)
|
| 270 |
+
|
| 271 |
+
u = max(subg, key=lambda u: len(cand & adj[u]))
|
| 272 |
+
ext_u = cand - adj[u]
|
| 273 |
+
|
| 274 |
+
try:
|
| 275 |
+
while True:
|
| 276 |
+
if ext_u:
|
| 277 |
+
q = ext_u.pop()
|
| 278 |
+
cand.remove(q)
|
| 279 |
+
Q[-1] = q
|
| 280 |
+
adj_q = adj[q]
|
| 281 |
+
subg_q = subg & adj_q
|
| 282 |
+
if not subg_q:
|
| 283 |
+
yield Q[:]
|
| 284 |
+
else:
|
| 285 |
+
cand_q = cand & adj_q
|
| 286 |
+
if cand_q:
|
| 287 |
+
stack.append((subg, cand, ext_u))
|
| 288 |
+
Q.append(None)
|
| 289 |
+
subg = subg_q
|
| 290 |
+
cand = cand_q
|
| 291 |
+
u = max(subg, key=lambda u: len(cand & adj[u]))
|
| 292 |
+
ext_u = cand - adj[u]
|
| 293 |
+
else:
|
| 294 |
+
Q.pop()
|
| 295 |
+
subg, cand, ext_u = stack.pop()
|
| 296 |
+
except IndexError:
|
| 297 |
+
pass
|
| 298 |
+
|
| 299 |
+
|
| 300 |
+
# TODO Should this also be not implemented for directed graphs?
|
| 301 |
+
@nx._dispatchable
|
| 302 |
+
def find_cliques_recursive(G, nodes=None):
|
| 303 |
+
"""Returns all maximal cliques in a graph.
|
| 304 |
+
|
| 305 |
+
For each node *v*, a *maximal clique for v* is a largest complete
|
| 306 |
+
subgraph containing *v*. The largest maximal clique is sometimes
|
| 307 |
+
called the *maximum clique*.
|
| 308 |
+
|
| 309 |
+
This function returns an iterator over cliques, each of which is a
|
| 310 |
+
list of nodes. It is a recursive implementation, so may suffer from
|
| 311 |
+
recursion depth issues, but is included for pedagogical reasons.
|
| 312 |
+
For a non-recursive implementation, see :func:`find_cliques`.
|
| 313 |
+
|
| 314 |
+
This function accepts a list of `nodes` and only the maximal cliques
|
| 315 |
+
containing all of these `nodes` are returned. It can considerably speed up
|
| 316 |
+
the running time if some specific cliques are desired.
|
| 317 |
+
|
| 318 |
+
Parameters
|
| 319 |
+
----------
|
| 320 |
+
G : NetworkX graph
|
| 321 |
+
|
| 322 |
+
nodes : list, optional (default=None)
|
| 323 |
+
If provided, only yield *maximal cliques* containing all nodes in `nodes`.
|
| 324 |
+
If `nodes` isn't a clique itself, a ValueError is raised.
|
| 325 |
+
|
| 326 |
+
Returns
|
| 327 |
+
-------
|
| 328 |
+
iterator
|
| 329 |
+
An iterator over maximal cliques, each of which is a list of
|
| 330 |
+
nodes in `G`. If `nodes` is provided, only the maximal cliques
|
| 331 |
+
containing all the nodes in `nodes` are yielded. The order of
|
| 332 |
+
cliques is arbitrary.
|
| 333 |
+
|
| 334 |
+
Raises
|
| 335 |
+
------
|
| 336 |
+
ValueError
|
| 337 |
+
If `nodes` is not a clique.
|
| 338 |
+
|
| 339 |
+
See Also
|
| 340 |
+
--------
|
| 341 |
+
find_cliques
|
| 342 |
+
An iterative version of the same algorithm. See docstring for examples.
|
| 343 |
+
|
| 344 |
+
Notes
|
| 345 |
+
-----
|
| 346 |
+
To obtain a list of all maximal cliques, use
|
| 347 |
+
`list(find_cliques_recursive(G))`. However, be aware that in the
|
| 348 |
+
worst-case, the length of this list can be exponential in the number
|
| 349 |
+
of nodes in the graph. This function avoids storing all cliques in memory
|
| 350 |
+
by only keeping current candidate node lists in memory during its search.
|
| 351 |
+
|
| 352 |
+
This implementation is based on the algorithm published by Bron and
|
| 353 |
+
Kerbosch (1973) [1]_, as adapted by Tomita, Tanaka and Takahashi
|
| 354 |
+
(2006) [2]_ and discussed in Cazals and Karande (2008) [3]_. For a
|
| 355 |
+
non-recursive implementation, see :func:`find_cliques`.
|
| 356 |
+
|
| 357 |
+
This algorithm ignores self-loops and parallel edges, since cliques
|
| 358 |
+
are not conventionally defined with such edges.
|
| 359 |
+
|
| 360 |
+
References
|
| 361 |
+
----------
|
| 362 |
+
.. [1] Bron, C. and Kerbosch, J.
|
| 363 |
+
"Algorithm 457: finding all cliques of an undirected graph".
|
| 364 |
+
*Communications of the ACM* 16, 9 (Sep. 1973), 575--577.
|
| 365 |
+
<http://portal.acm.org/citation.cfm?doid=362342.362367>
|
| 366 |
+
|
| 367 |
+
.. [2] Etsuji Tomita, Akira Tanaka, Haruhisa Takahashi,
|
| 368 |
+
"The worst-case time complexity for generating all maximal
|
| 369 |
+
cliques and computational experiments",
|
| 370 |
+
*Theoretical Computer Science*, Volume 363, Issue 1,
|
| 371 |
+
Computing and Combinatorics,
|
| 372 |
+
10th Annual International Conference on
|
| 373 |
+
Computing and Combinatorics (COCOON 2004), 25 October 2006, Pages 28--42
|
| 374 |
+
<https://doi.org/10.1016/j.tcs.2006.06.015>
|
| 375 |
+
|
| 376 |
+
.. [3] F. Cazals, C. Karande,
|
| 377 |
+
"A note on the problem of reporting maximal cliques",
|
| 378 |
+
*Theoretical Computer Science*,
|
| 379 |
+
Volume 407, Issues 1--3, 6 November 2008, Pages 564--568,
|
| 380 |
+
<https://doi.org/10.1016/j.tcs.2008.05.010>
|
| 381 |
+
|
| 382 |
+
"""
|
| 383 |
+
if len(G) == 0:
|
| 384 |
+
return iter([])
|
| 385 |
+
|
| 386 |
+
adj = {u: {v for v in G[u] if v != u} for u in G}
|
| 387 |
+
|
| 388 |
+
# Initialize Q with the given nodes and subg, cand with their nbrs
|
| 389 |
+
Q = nodes[:] if nodes is not None else []
|
| 390 |
+
cand_init = set(G)
|
| 391 |
+
for node in Q:
|
| 392 |
+
if node not in cand_init:
|
| 393 |
+
raise ValueError(f"The given `nodes` {nodes} do not form a clique")
|
| 394 |
+
cand_init &= adj[node]
|
| 395 |
+
|
| 396 |
+
if not cand_init:
|
| 397 |
+
return iter([Q])
|
| 398 |
+
|
| 399 |
+
subg_init = cand_init.copy()
|
| 400 |
+
|
| 401 |
+
def expand(subg, cand):
|
| 402 |
+
u = max(subg, key=lambda u: len(cand & adj[u]))
|
| 403 |
+
for q in cand - adj[u]:
|
| 404 |
+
cand.remove(q)
|
| 405 |
+
Q.append(q)
|
| 406 |
+
adj_q = adj[q]
|
| 407 |
+
subg_q = subg & adj_q
|
| 408 |
+
if not subg_q:
|
| 409 |
+
yield Q[:]
|
| 410 |
+
else:
|
| 411 |
+
cand_q = cand & adj_q
|
| 412 |
+
if cand_q:
|
| 413 |
+
yield from expand(subg_q, cand_q)
|
| 414 |
+
Q.pop()
|
| 415 |
+
|
| 416 |
+
return expand(subg_init, cand_init)
|
| 417 |
+
|
| 418 |
+
|
| 419 |
+
@nx._dispatchable(returns_graph=True)
|
| 420 |
+
def make_max_clique_graph(G, create_using=None):
|
| 421 |
+
"""Returns the maximal clique graph of the given graph.
|
| 422 |
+
|
| 423 |
+
The nodes of the maximal clique graph of `G` are the cliques of
|
| 424 |
+
`G` and an edge joins two cliques if the cliques are not disjoint.
|
| 425 |
+
|
| 426 |
+
Parameters
|
| 427 |
+
----------
|
| 428 |
+
G : NetworkX graph
|
| 429 |
+
|
| 430 |
+
create_using : NetworkX graph constructor, optional (default=nx.Graph)
|
| 431 |
+
Graph type to create. If graph instance, then cleared before populated.
|
| 432 |
+
|
| 433 |
+
Returns
|
| 434 |
+
-------
|
| 435 |
+
NetworkX graph
|
| 436 |
+
A graph whose nodes are the cliques of `G` and whose edges
|
| 437 |
+
join two cliques if they are not disjoint.
|
| 438 |
+
|
| 439 |
+
Notes
|
| 440 |
+
-----
|
| 441 |
+
This function behaves like the following code::
|
| 442 |
+
|
| 443 |
+
import networkx as nx
|
| 444 |
+
|
| 445 |
+
G = nx.make_clique_bipartite(G)
|
| 446 |
+
cliques = [v for v in G.nodes() if G.nodes[v]["bipartite"] == 0]
|
| 447 |
+
G = nx.bipartite.projected_graph(G, cliques)
|
| 448 |
+
G = nx.relabel_nodes(G, {-v: v - 1 for v in G})
|
| 449 |
+
|
| 450 |
+
It should be faster, though, since it skips all the intermediate
|
| 451 |
+
steps.
|
| 452 |
+
|
| 453 |
+
"""
|
| 454 |
+
if create_using is None:
|
| 455 |
+
B = G.__class__()
|
| 456 |
+
else:
|
| 457 |
+
B = nx.empty_graph(0, create_using)
|
| 458 |
+
cliques = list(enumerate(set(c) for c in find_cliques(G)))
|
| 459 |
+
# Add a numbered node for each clique.
|
| 460 |
+
B.add_nodes_from(i for i, c in cliques)
|
| 461 |
+
# Join cliques by an edge if they share a node.
|
| 462 |
+
clique_pairs = combinations(cliques, 2)
|
| 463 |
+
B.add_edges_from((i, j) for (i, c1), (j, c2) in clique_pairs if c1 & c2)
|
| 464 |
+
return B
|
| 465 |
+
|
| 466 |
+
|
| 467 |
+
@nx._dispatchable(returns_graph=True)
|
| 468 |
+
def make_clique_bipartite(G, fpos=None, create_using=None, name=None):
|
| 469 |
+
"""Returns the bipartite clique graph corresponding to `G`.
|
| 470 |
+
|
| 471 |
+
In the returned bipartite graph, the "bottom" nodes are the nodes of
|
| 472 |
+
`G` and the "top" nodes represent the maximal cliques of `G`.
|
| 473 |
+
There is an edge from node *v* to clique *C* in the returned graph
|
| 474 |
+
if and only if *v* is an element of *C*.
|
| 475 |
+
|
| 476 |
+
Parameters
|
| 477 |
+
----------
|
| 478 |
+
G : NetworkX graph
|
| 479 |
+
An undirected graph.
|
| 480 |
+
|
| 481 |
+
fpos : bool
|
| 482 |
+
If True or not None, the returned graph will have an
|
| 483 |
+
additional attribute, `pos`, a dictionary mapping node to
|
| 484 |
+
position in the Euclidean plane.
|
| 485 |
+
|
| 486 |
+
create_using : NetworkX graph constructor, optional (default=nx.Graph)
|
| 487 |
+
Graph type to create. If graph instance, then cleared before populated.
|
| 488 |
+
|
| 489 |
+
Returns
|
| 490 |
+
-------
|
| 491 |
+
NetworkX graph
|
| 492 |
+
A bipartite graph whose "bottom" set is the nodes of the graph
|
| 493 |
+
`G`, whose "top" set is the cliques of `G`, and whose edges
|
| 494 |
+
join nodes of `G` to the cliques that contain them.
|
| 495 |
+
|
| 496 |
+
The nodes of the graph `G` have the node attribute
|
| 497 |
+
'bipartite' set to 1 and the nodes representing cliques
|
| 498 |
+
have the node attribute 'bipartite' set to 0, as is the
|
| 499 |
+
convention for bipartite graphs in NetworkX.
|
| 500 |
+
|
| 501 |
+
"""
|
| 502 |
+
B = nx.empty_graph(0, create_using)
|
| 503 |
+
B.clear()
|
| 504 |
+
# The "bottom" nodes in the bipartite graph are the nodes of the
|
| 505 |
+
# original graph, G.
|
| 506 |
+
B.add_nodes_from(G, bipartite=1)
|
| 507 |
+
for i, cl in enumerate(find_cliques(G)):
|
| 508 |
+
# The "top" nodes in the bipartite graph are the cliques. These
|
| 509 |
+
# nodes get negative numbers as labels.
|
| 510 |
+
name = -i - 1
|
| 511 |
+
B.add_node(name, bipartite=0)
|
| 512 |
+
B.add_edges_from((v, name) for v in cl)
|
| 513 |
+
return B
|
| 514 |
+
|
| 515 |
+
|
| 516 |
+
@nx._dispatchable
|
| 517 |
+
def node_clique_number(G, nodes=None, cliques=None, separate_nodes=False):
|
| 518 |
+
"""Returns the size of the largest maximal clique containing each given node.
|
| 519 |
+
|
| 520 |
+
Returns a single or list depending on input nodes.
|
| 521 |
+
An optional list of cliques can be input if already computed.
|
| 522 |
+
|
| 523 |
+
Parameters
|
| 524 |
+
----------
|
| 525 |
+
G : NetworkX graph
|
| 526 |
+
An undirected graph.
|
| 527 |
+
|
| 528 |
+
cliques : list, optional (default=None)
|
| 529 |
+
A list of cliques, each of which is itself a list of nodes.
|
| 530 |
+
If not specified, the list of all cliques will be computed
|
| 531 |
+
using :func:`find_cliques`.
|
| 532 |
+
|
| 533 |
+
Returns
|
| 534 |
+
-------
|
| 535 |
+
int or dict
|
| 536 |
+
If `nodes` is a single node, returns the size of the
|
| 537 |
+
largest maximal clique in `G` containing that node.
|
| 538 |
+
Otherwise return a dict keyed by node to the size
|
| 539 |
+
of the largest maximal clique containing that node.
|
| 540 |
+
|
| 541 |
+
See Also
|
| 542 |
+
--------
|
| 543 |
+
find_cliques
|
| 544 |
+
find_cliques yields the maximal cliques of G.
|
| 545 |
+
It accepts a `nodes` argument which restricts consideration to
|
| 546 |
+
maximal cliques containing all the given `nodes`.
|
| 547 |
+
The search for the cliques is optimized for `nodes`.
|
| 548 |
+
"""
|
| 549 |
+
if cliques is None:
|
| 550 |
+
if nodes is not None:
|
| 551 |
+
# Use ego_graph to decrease size of graph
|
| 552 |
+
# check for single node
|
| 553 |
+
if nodes in G:
|
| 554 |
+
return max(len(c) for c in find_cliques(nx.ego_graph(G, nodes)))
|
| 555 |
+
# handle multiple nodes
|
| 556 |
+
return {
|
| 557 |
+
n: max(len(c) for c in find_cliques(nx.ego_graph(G, n))) for n in nodes
|
| 558 |
+
}
|
| 559 |
+
|
| 560 |
+
# nodes is None--find all cliques
|
| 561 |
+
cliques = list(find_cliques(G))
|
| 562 |
+
|
| 563 |
+
# single node requested
|
| 564 |
+
if nodes in G:
|
| 565 |
+
return max(len(c) for c in cliques if nodes in c)
|
| 566 |
+
|
| 567 |
+
# multiple nodes requested
|
| 568 |
+
# preprocess all nodes (faster than one at a time for even 2 nodes)
|
| 569 |
+
size_for_n = defaultdict(int)
|
| 570 |
+
for c in cliques:
|
| 571 |
+
size_of_c = len(c)
|
| 572 |
+
for n in c:
|
| 573 |
+
if size_for_n[n] < size_of_c:
|
| 574 |
+
size_for_n[n] = size_of_c
|
| 575 |
+
if nodes is None:
|
| 576 |
+
return size_for_n
|
| 577 |
+
return {n: size_for_n[n] for n in nodes}
|
| 578 |
+
|
| 579 |
+
|
| 580 |
+
def number_of_cliques(G, nodes=None, cliques=None):
|
| 581 |
+
"""Returns the number of maximal cliques for each node.
|
| 582 |
+
|
| 583 |
+
Returns a single or list depending on input nodes.
|
| 584 |
+
Optional list of cliques can be input if already computed.
|
| 585 |
+
"""
|
| 586 |
+
if cliques is None:
|
| 587 |
+
cliques = find_cliques(G)
|
| 588 |
+
|
| 589 |
+
if nodes is None:
|
| 590 |
+
nodes = list(G.nodes()) # none, get entire graph
|
| 591 |
+
|
| 592 |
+
if not isinstance(nodes, list): # check for a list
|
| 593 |
+
v = nodes
|
| 594 |
+
# assume it is a single value
|
| 595 |
+
numcliq = sum(1 for c in cliques if v in c)
|
| 596 |
+
else:
|
| 597 |
+
numcliq = Counter(chain.from_iterable(cliques))
|
| 598 |
+
numcliq = {v: numcliq[v] for v in nodes} # return a dict
|
| 599 |
+
return numcliq
|
| 600 |
+
|
| 601 |
+
|
| 602 |
+
class MaxWeightClique:
|
| 603 |
+
"""A class for the maximum weight clique algorithm.
|
| 604 |
+
|
| 605 |
+
This class is a helper for the `max_weight_clique` function. The class
|
| 606 |
+
should not normally be used directly.
|
| 607 |
+
|
| 608 |
+
Parameters
|
| 609 |
+
----------
|
| 610 |
+
G : NetworkX graph
|
| 611 |
+
The undirected graph for which a maximum weight clique is sought
|
| 612 |
+
weight : string or None, optional (default='weight')
|
| 613 |
+
The node attribute that holds the integer value used as a weight.
|
| 614 |
+
If None, then each node has weight 1.
|
| 615 |
+
|
| 616 |
+
Attributes
|
| 617 |
+
----------
|
| 618 |
+
G : NetworkX graph
|
| 619 |
+
The undirected graph for which a maximum weight clique is sought
|
| 620 |
+
node_weights: dict
|
| 621 |
+
The weight of each node
|
| 622 |
+
incumbent_nodes : list
|
| 623 |
+
The nodes of the incumbent clique (the best clique found so far)
|
| 624 |
+
incumbent_weight: int
|
| 625 |
+
The weight of the incumbent clique
|
| 626 |
+
"""
|
| 627 |
+
|
| 628 |
+
def __init__(self, G, weight):
|
| 629 |
+
self.G = G
|
| 630 |
+
self.incumbent_nodes = []
|
| 631 |
+
self.incumbent_weight = 0
|
| 632 |
+
|
| 633 |
+
if weight is None:
|
| 634 |
+
self.node_weights = dict.fromkeys(G.nodes(), 1)
|
| 635 |
+
else:
|
| 636 |
+
for v in G.nodes():
|
| 637 |
+
if weight not in G.nodes[v]:
|
| 638 |
+
errmsg = f"Node {v!r} does not have the requested weight field."
|
| 639 |
+
raise KeyError(errmsg)
|
| 640 |
+
if not isinstance(G.nodes[v][weight], int):
|
| 641 |
+
errmsg = f"The {weight!r} field of node {v!r} is not an integer."
|
| 642 |
+
raise ValueError(errmsg)
|
| 643 |
+
self.node_weights = {v: G.nodes[v][weight] for v in G.nodes()}
|
| 644 |
+
|
| 645 |
+
def update_incumbent_if_improved(self, C, C_weight):
|
| 646 |
+
"""Update the incumbent if the node set C has greater weight.
|
| 647 |
+
|
| 648 |
+
C is assumed to be a clique.
|
| 649 |
+
"""
|
| 650 |
+
if C_weight > self.incumbent_weight:
|
| 651 |
+
self.incumbent_nodes = C[:]
|
| 652 |
+
self.incumbent_weight = C_weight
|
| 653 |
+
|
| 654 |
+
def greedily_find_independent_set(self, P):
|
| 655 |
+
"""Greedily find an independent set of nodes from a set of
|
| 656 |
+
nodes P."""
|
| 657 |
+
independent_set = []
|
| 658 |
+
P = P[:]
|
| 659 |
+
while P:
|
| 660 |
+
v = P[0]
|
| 661 |
+
independent_set.append(v)
|
| 662 |
+
P = [w for w in P if v != w and not self.G.has_edge(v, w)]
|
| 663 |
+
return independent_set
|
| 664 |
+
|
| 665 |
+
def find_branching_nodes(self, P, target):
|
| 666 |
+
"""Find a set of nodes to branch on."""
|
| 667 |
+
residual_wt = {v: self.node_weights[v] for v in P}
|
| 668 |
+
total_wt = 0
|
| 669 |
+
P = P[:]
|
| 670 |
+
while P:
|
| 671 |
+
independent_set = self.greedily_find_independent_set(P)
|
| 672 |
+
min_wt_in_class = min(residual_wt[v] for v in independent_set)
|
| 673 |
+
total_wt += min_wt_in_class
|
| 674 |
+
if total_wt > target:
|
| 675 |
+
break
|
| 676 |
+
for v in independent_set:
|
| 677 |
+
residual_wt[v] -= min_wt_in_class
|
| 678 |
+
P = [v for v in P if residual_wt[v] != 0]
|
| 679 |
+
return P
|
| 680 |
+
|
| 681 |
+
def expand(self, C, C_weight, P):
|
| 682 |
+
"""Look for the best clique that contains all the nodes in C and zero or
|
| 683 |
+
more of the nodes in P, backtracking if it can be shown that no such
|
| 684 |
+
clique has greater weight than the incumbent.
|
| 685 |
+
"""
|
| 686 |
+
self.update_incumbent_if_improved(C, C_weight)
|
| 687 |
+
branching_nodes = self.find_branching_nodes(P, self.incumbent_weight - C_weight)
|
| 688 |
+
while branching_nodes:
|
| 689 |
+
v = branching_nodes.pop()
|
| 690 |
+
P.remove(v)
|
| 691 |
+
new_C = C + [v]
|
| 692 |
+
new_C_weight = C_weight + self.node_weights[v]
|
| 693 |
+
new_P = [w for w in P if self.G.has_edge(v, w)]
|
| 694 |
+
self.expand(new_C, new_C_weight, new_P)
|
| 695 |
+
|
| 696 |
+
def find_max_weight_clique(self):
|
| 697 |
+
"""Find a maximum weight clique."""
|
| 698 |
+
# Sort nodes in reverse order of degree for speed
|
| 699 |
+
nodes = sorted(self.G.nodes(), key=lambda v: self.G.degree(v), reverse=True)
|
| 700 |
+
nodes = [v for v in nodes if self.node_weights[v] > 0]
|
| 701 |
+
self.expand([], 0, nodes)
|
| 702 |
+
|
| 703 |
+
|
| 704 |
+
@not_implemented_for("directed")
|
| 705 |
+
@nx._dispatchable(node_attrs="weight")
|
| 706 |
+
def max_weight_clique(G, weight="weight"):
|
| 707 |
+
"""Find a maximum weight clique in G.
|
| 708 |
+
|
| 709 |
+
A *clique* in a graph is a set of nodes such that every two distinct nodes
|
| 710 |
+
are adjacent. The *weight* of a clique is the sum of the weights of its
|
| 711 |
+
nodes. A *maximum weight clique* of graph G is a clique C in G such that
|
| 712 |
+
no clique in G has weight greater than the weight of C.
|
| 713 |
+
|
| 714 |
+
Parameters
|
| 715 |
+
----------
|
| 716 |
+
G : NetworkX graph
|
| 717 |
+
Undirected graph
|
| 718 |
+
weight : string or None, optional (default='weight')
|
| 719 |
+
The node attribute that holds the integer value used as a weight.
|
| 720 |
+
If None, then each node has weight 1.
|
| 721 |
+
|
| 722 |
+
Returns
|
| 723 |
+
-------
|
| 724 |
+
clique : list
|
| 725 |
+
the nodes of a maximum weight clique
|
| 726 |
+
weight : int
|
| 727 |
+
the weight of a maximum weight clique
|
| 728 |
+
|
| 729 |
+
Notes
|
| 730 |
+
-----
|
| 731 |
+
The implementation is recursive, and therefore it may run into recursion
|
| 732 |
+
depth issues if G contains a clique whose number of nodes is close to the
|
| 733 |
+
recursion depth limit.
|
| 734 |
+
|
| 735 |
+
At each search node, the algorithm greedily constructs a weighted
|
| 736 |
+
independent set cover of part of the graph in order to find a small set of
|
| 737 |
+
nodes on which to branch. The algorithm is very similar to the algorithm
|
| 738 |
+
of Tavares et al. [1]_, other than the fact that the NetworkX version does
|
| 739 |
+
not use bitsets. This style of algorithm for maximum weight clique (and
|
| 740 |
+
maximum weight independent set, which is the same problem but on the
|
| 741 |
+
complement graph) has a decades-long history. See Algorithm B of Warren
|
| 742 |
+
and Hicks [2]_ and the references in that paper.
|
| 743 |
+
|
| 744 |
+
References
|
| 745 |
+
----------
|
| 746 |
+
.. [1] Tavares, W.A., Neto, M.B.C., Rodrigues, C.D., Michelon, P.: Um
|
| 747 |
+
algoritmo de branch and bound para o problema da clique máxima
|
| 748 |
+
ponderada. Proceedings of XLVII SBPO 1 (2015).
|
| 749 |
+
|
| 750 |
+
.. [2] Warren, Jeffrey S, Hicks, Illya V.: Combinatorial Branch-and-Bound
|
| 751 |
+
for the Maximum Weight Independent Set Problem. Technical Report,
|
| 752 |
+
Texas A&M University (2016).
|
| 753 |
+
"""
|
| 754 |
+
|
| 755 |
+
mwc = MaxWeightClique(G, weight)
|
| 756 |
+
mwc.find_max_weight_clique()
|
| 757 |
+
return mwc.incumbent_nodes, mwc.incumbent_weight
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/cluster.py
ADDED
|
@@ -0,0 +1,658 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Algorithms to characterize the number of triangles in a graph."""
|
| 2 |
+
|
| 3 |
+
from collections import Counter
|
| 4 |
+
from itertools import chain, combinations
|
| 5 |
+
|
| 6 |
+
import networkx as nx
|
| 7 |
+
from networkx.utils import not_implemented_for
|
| 8 |
+
|
| 9 |
+
__all__ = [
|
| 10 |
+
"triangles",
|
| 11 |
+
"average_clustering",
|
| 12 |
+
"clustering",
|
| 13 |
+
"transitivity",
|
| 14 |
+
"square_clustering",
|
| 15 |
+
"generalized_degree",
|
| 16 |
+
]
|
| 17 |
+
|
| 18 |
+
|
| 19 |
+
@not_implemented_for("directed")
|
| 20 |
+
@nx._dispatchable
|
| 21 |
+
def triangles(G, nodes=None):
|
| 22 |
+
"""Compute the number of triangles.
|
| 23 |
+
|
| 24 |
+
Finds the number of triangles that include a node as one vertex.
|
| 25 |
+
|
| 26 |
+
Parameters
|
| 27 |
+
----------
|
| 28 |
+
G : graph
|
| 29 |
+
A networkx graph
|
| 30 |
+
|
| 31 |
+
nodes : node, iterable of nodes, or None (default=None)
|
| 32 |
+
If a singleton node, return the number of triangles for that node.
|
| 33 |
+
If an iterable, compute the number of triangles for each of those nodes.
|
| 34 |
+
If `None` (the default) compute the number of triangles for all nodes in `G`.
|
| 35 |
+
|
| 36 |
+
Returns
|
| 37 |
+
-------
|
| 38 |
+
out : dict or int
|
| 39 |
+
If `nodes` is a container of nodes, returns number of triangles keyed by node (dict).
|
| 40 |
+
If `nodes` is a specific node, returns number of triangles for the node (int).
|
| 41 |
+
|
| 42 |
+
Examples
|
| 43 |
+
--------
|
| 44 |
+
>>> G = nx.complete_graph(5)
|
| 45 |
+
>>> print(nx.triangles(G, 0))
|
| 46 |
+
6
|
| 47 |
+
>>> print(nx.triangles(G))
|
| 48 |
+
{0: 6, 1: 6, 2: 6, 3: 6, 4: 6}
|
| 49 |
+
>>> print(list(nx.triangles(G, [0, 1]).values()))
|
| 50 |
+
[6, 6]
|
| 51 |
+
|
| 52 |
+
Notes
|
| 53 |
+
-----
|
| 54 |
+
Self loops are ignored.
|
| 55 |
+
|
| 56 |
+
"""
|
| 57 |
+
if nodes is not None:
|
| 58 |
+
# If `nodes` represents a single node, return only its number of triangles
|
| 59 |
+
if nodes in G:
|
| 60 |
+
return next(_triangles_and_degree_iter(G, nodes))[2] // 2
|
| 61 |
+
|
| 62 |
+
# if `nodes` is a container of nodes, then return a
|
| 63 |
+
# dictionary mapping node to number of triangles.
|
| 64 |
+
return {v: t // 2 for v, d, t, _ in _triangles_and_degree_iter(G, nodes)}
|
| 65 |
+
|
| 66 |
+
# if nodes is None, then compute triangles for the complete graph
|
| 67 |
+
|
| 68 |
+
# dict used to avoid visiting the same nodes twice
|
| 69 |
+
# this allows calculating/counting each triangle only once
|
| 70 |
+
later_nbrs = {}
|
| 71 |
+
|
| 72 |
+
# iterate over the nodes in a graph
|
| 73 |
+
for node, neighbors in G.adjacency():
|
| 74 |
+
later_nbrs[node] = {n for n in neighbors if n not in later_nbrs and n != node}
|
| 75 |
+
|
| 76 |
+
# instantiate Counter for each node to include isolated nodes
|
| 77 |
+
# add 1 to the count if a nodes neighbor's neighbor is also a neighbor
|
| 78 |
+
triangle_counts = Counter(dict.fromkeys(G, 0))
|
| 79 |
+
for node1, neighbors in later_nbrs.items():
|
| 80 |
+
for node2 in neighbors:
|
| 81 |
+
third_nodes = neighbors & later_nbrs[node2]
|
| 82 |
+
m = len(third_nodes)
|
| 83 |
+
triangle_counts[node1] += m
|
| 84 |
+
triangle_counts[node2] += m
|
| 85 |
+
triangle_counts.update(third_nodes)
|
| 86 |
+
|
| 87 |
+
return dict(triangle_counts)
|
| 88 |
+
|
| 89 |
+
|
| 90 |
+
@not_implemented_for("multigraph")
|
| 91 |
+
def _triangles_and_degree_iter(G, nodes=None):
|
| 92 |
+
"""Return an iterator of (node, degree, triangles, generalized degree).
|
| 93 |
+
|
| 94 |
+
This double counts triangles so you may want to divide by 2.
|
| 95 |
+
See degree(), triangles() and generalized_degree() for definitions
|
| 96 |
+
and details.
|
| 97 |
+
|
| 98 |
+
"""
|
| 99 |
+
if nodes is None:
|
| 100 |
+
nodes_nbrs = G.adj.items()
|
| 101 |
+
else:
|
| 102 |
+
nodes_nbrs = ((n, G[n]) for n in G.nbunch_iter(nodes))
|
| 103 |
+
|
| 104 |
+
for v, v_nbrs in nodes_nbrs:
|
| 105 |
+
vs = set(v_nbrs) - {v}
|
| 106 |
+
gen_degree = Counter(len(vs & (set(G[w]) - {w})) for w in vs)
|
| 107 |
+
ntriangles = sum(k * val for k, val in gen_degree.items())
|
| 108 |
+
yield (v, len(vs), ntriangles, gen_degree)
|
| 109 |
+
|
| 110 |
+
|
| 111 |
+
@not_implemented_for("multigraph")
|
| 112 |
+
def _weighted_triangles_and_degree_iter(G, nodes=None, weight="weight"):
|
| 113 |
+
"""Return an iterator of (node, degree, weighted_triangles).
|
| 114 |
+
|
| 115 |
+
Used for weighted clustering.
|
| 116 |
+
Note: this returns the geometric average weight of edges in the triangle.
|
| 117 |
+
Also, each triangle is counted twice (each direction).
|
| 118 |
+
So you may want to divide by 2.
|
| 119 |
+
|
| 120 |
+
"""
|
| 121 |
+
import numpy as np
|
| 122 |
+
|
| 123 |
+
if weight is None or G.number_of_edges() == 0:
|
| 124 |
+
max_weight = 1
|
| 125 |
+
else:
|
| 126 |
+
max_weight = max(d.get(weight, 1) for u, v, d in G.edges(data=True))
|
| 127 |
+
if nodes is None:
|
| 128 |
+
nodes_nbrs = G.adj.items()
|
| 129 |
+
else:
|
| 130 |
+
nodes_nbrs = ((n, G[n]) for n in G.nbunch_iter(nodes))
|
| 131 |
+
|
| 132 |
+
def wt(u, v):
|
| 133 |
+
return G[u][v].get(weight, 1) / max_weight
|
| 134 |
+
|
| 135 |
+
for i, nbrs in nodes_nbrs:
|
| 136 |
+
inbrs = set(nbrs) - {i}
|
| 137 |
+
weighted_triangles = 0
|
| 138 |
+
seen = set()
|
| 139 |
+
for j in inbrs:
|
| 140 |
+
seen.add(j)
|
| 141 |
+
# This avoids counting twice -- we double at the end.
|
| 142 |
+
jnbrs = set(G[j]) - seen
|
| 143 |
+
# Only compute the edge weight once, before the inner inner
|
| 144 |
+
# loop.
|
| 145 |
+
wij = wt(i, j)
|
| 146 |
+
weighted_triangles += np.cbrt(
|
| 147 |
+
[(wij * wt(j, k) * wt(k, i)) for k in inbrs & jnbrs]
|
| 148 |
+
).sum()
|
| 149 |
+
yield (i, len(inbrs), 2 * float(weighted_triangles))
|
| 150 |
+
|
| 151 |
+
|
| 152 |
+
@not_implemented_for("multigraph")
|
| 153 |
+
def _directed_triangles_and_degree_iter(G, nodes=None):
|
| 154 |
+
"""Return an iterator of
|
| 155 |
+
(node, total_degree, reciprocal_degree, directed_triangles).
|
| 156 |
+
|
| 157 |
+
Used for directed clustering.
|
| 158 |
+
Note that unlike `_triangles_and_degree_iter()`, this function counts
|
| 159 |
+
directed triangles so does not count triangles twice.
|
| 160 |
+
|
| 161 |
+
"""
|
| 162 |
+
nodes_nbrs = ((n, G._pred[n], G._succ[n]) for n in G.nbunch_iter(nodes))
|
| 163 |
+
|
| 164 |
+
for i, preds, succs in nodes_nbrs:
|
| 165 |
+
ipreds = set(preds) - {i}
|
| 166 |
+
isuccs = set(succs) - {i}
|
| 167 |
+
|
| 168 |
+
directed_triangles = 0
|
| 169 |
+
for j in chain(ipreds, isuccs):
|
| 170 |
+
jpreds = set(G._pred[j]) - {j}
|
| 171 |
+
jsuccs = set(G._succ[j]) - {j}
|
| 172 |
+
directed_triangles += sum(
|
| 173 |
+
1
|
| 174 |
+
for k in chain(
|
| 175 |
+
(ipreds & jpreds),
|
| 176 |
+
(ipreds & jsuccs),
|
| 177 |
+
(isuccs & jpreds),
|
| 178 |
+
(isuccs & jsuccs),
|
| 179 |
+
)
|
| 180 |
+
)
|
| 181 |
+
dtotal = len(ipreds) + len(isuccs)
|
| 182 |
+
dbidirectional = len(ipreds & isuccs)
|
| 183 |
+
yield (i, dtotal, dbidirectional, directed_triangles)
|
| 184 |
+
|
| 185 |
+
|
| 186 |
+
@not_implemented_for("multigraph")
|
| 187 |
+
def _directed_weighted_triangles_and_degree_iter(G, nodes=None, weight="weight"):
|
| 188 |
+
"""Return an iterator of
|
| 189 |
+
(node, total_degree, reciprocal_degree, directed_weighted_triangles).
|
| 190 |
+
|
| 191 |
+
Used for directed weighted clustering.
|
| 192 |
+
Note that unlike `_weighted_triangles_and_degree_iter()`, this function counts
|
| 193 |
+
directed triangles so does not count triangles twice.
|
| 194 |
+
|
| 195 |
+
"""
|
| 196 |
+
import numpy as np
|
| 197 |
+
|
| 198 |
+
if weight is None or G.number_of_edges() == 0:
|
| 199 |
+
max_weight = 1
|
| 200 |
+
else:
|
| 201 |
+
max_weight = max(d.get(weight, 1) for u, v, d in G.edges(data=True))
|
| 202 |
+
|
| 203 |
+
nodes_nbrs = ((n, G._pred[n], G._succ[n]) for n in G.nbunch_iter(nodes))
|
| 204 |
+
|
| 205 |
+
def wt(u, v):
|
| 206 |
+
return G[u][v].get(weight, 1) / max_weight
|
| 207 |
+
|
| 208 |
+
for i, preds, succs in nodes_nbrs:
|
| 209 |
+
ipreds = set(preds) - {i}
|
| 210 |
+
isuccs = set(succs) - {i}
|
| 211 |
+
|
| 212 |
+
directed_triangles = 0
|
| 213 |
+
for j in ipreds:
|
| 214 |
+
jpreds = set(G._pred[j]) - {j}
|
| 215 |
+
jsuccs = set(G._succ[j]) - {j}
|
| 216 |
+
directed_triangles += np.cbrt(
|
| 217 |
+
[(wt(j, i) * wt(k, i) * wt(k, j)) for k in ipreds & jpreds]
|
| 218 |
+
).sum()
|
| 219 |
+
directed_triangles += np.cbrt(
|
| 220 |
+
[(wt(j, i) * wt(k, i) * wt(j, k)) for k in ipreds & jsuccs]
|
| 221 |
+
).sum()
|
| 222 |
+
directed_triangles += np.cbrt(
|
| 223 |
+
[(wt(j, i) * wt(i, k) * wt(k, j)) for k in isuccs & jpreds]
|
| 224 |
+
).sum()
|
| 225 |
+
directed_triangles += np.cbrt(
|
| 226 |
+
[(wt(j, i) * wt(i, k) * wt(j, k)) for k in isuccs & jsuccs]
|
| 227 |
+
).sum()
|
| 228 |
+
|
| 229 |
+
for j in isuccs:
|
| 230 |
+
jpreds = set(G._pred[j]) - {j}
|
| 231 |
+
jsuccs = set(G._succ[j]) - {j}
|
| 232 |
+
directed_triangles += np.cbrt(
|
| 233 |
+
[(wt(i, j) * wt(k, i) * wt(k, j)) for k in ipreds & jpreds]
|
| 234 |
+
).sum()
|
| 235 |
+
directed_triangles += np.cbrt(
|
| 236 |
+
[(wt(i, j) * wt(k, i) * wt(j, k)) for k in ipreds & jsuccs]
|
| 237 |
+
).sum()
|
| 238 |
+
directed_triangles += np.cbrt(
|
| 239 |
+
[(wt(i, j) * wt(i, k) * wt(k, j)) for k in isuccs & jpreds]
|
| 240 |
+
).sum()
|
| 241 |
+
directed_triangles += np.cbrt(
|
| 242 |
+
[(wt(i, j) * wt(i, k) * wt(j, k)) for k in isuccs & jsuccs]
|
| 243 |
+
).sum()
|
| 244 |
+
|
| 245 |
+
dtotal = len(ipreds) + len(isuccs)
|
| 246 |
+
dbidirectional = len(ipreds & isuccs)
|
| 247 |
+
yield (i, dtotal, dbidirectional, float(directed_triangles))
|
| 248 |
+
|
| 249 |
+
|
| 250 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 251 |
+
def average_clustering(G, nodes=None, weight=None, count_zeros=True):
|
| 252 |
+
r"""Compute the average clustering coefficient for the graph G.
|
| 253 |
+
|
| 254 |
+
The clustering coefficient for the graph is the average,
|
| 255 |
+
|
| 256 |
+
.. math::
|
| 257 |
+
|
| 258 |
+
C = \frac{1}{n}\sum_{v \in G} c_v,
|
| 259 |
+
|
| 260 |
+
where :math:`n` is the number of nodes in `G`.
|
| 261 |
+
|
| 262 |
+
Parameters
|
| 263 |
+
----------
|
| 264 |
+
G : graph
|
| 265 |
+
|
| 266 |
+
nodes : container of nodes, optional (default=all nodes in G)
|
| 267 |
+
Compute average clustering for nodes in this container.
|
| 268 |
+
|
| 269 |
+
weight : string or None, optional (default=None)
|
| 270 |
+
The edge attribute that holds the numerical value used as a weight.
|
| 271 |
+
If None, then each edge has weight 1.
|
| 272 |
+
|
| 273 |
+
count_zeros : bool
|
| 274 |
+
If False include only the nodes with nonzero clustering in the average.
|
| 275 |
+
|
| 276 |
+
Returns
|
| 277 |
+
-------
|
| 278 |
+
avg : float
|
| 279 |
+
Average clustering
|
| 280 |
+
|
| 281 |
+
Examples
|
| 282 |
+
--------
|
| 283 |
+
>>> G = nx.complete_graph(5)
|
| 284 |
+
>>> print(nx.average_clustering(G))
|
| 285 |
+
1.0
|
| 286 |
+
|
| 287 |
+
Notes
|
| 288 |
+
-----
|
| 289 |
+
This is a space saving routine; it might be faster
|
| 290 |
+
to use the clustering function to get a list and then take the average.
|
| 291 |
+
|
| 292 |
+
Self loops are ignored.
|
| 293 |
+
|
| 294 |
+
References
|
| 295 |
+
----------
|
| 296 |
+
.. [1] Generalizations of the clustering coefficient to weighted
|
| 297 |
+
complex networks by J. Saramäki, M. Kivelä, J.-P. Onnela,
|
| 298 |
+
K. Kaski, and J. Kertész, Physical Review E, 75 027105 (2007).
|
| 299 |
+
http://jponnela.com/web_documents/a9.pdf
|
| 300 |
+
.. [2] Marcus Kaiser, Mean clustering coefficients: the role of isolated
|
| 301 |
+
nodes and leafs on clustering measures for small-world networks.
|
| 302 |
+
https://arxiv.org/abs/0802.2512
|
| 303 |
+
"""
|
| 304 |
+
c = clustering(G, nodes, weight=weight).values()
|
| 305 |
+
if not count_zeros:
|
| 306 |
+
c = [v for v in c if abs(v) > 0]
|
| 307 |
+
return sum(c) / len(c)
|
| 308 |
+
|
| 309 |
+
|
| 310 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 311 |
+
def clustering(G, nodes=None, weight=None):
|
| 312 |
+
r"""Compute the clustering coefficient for nodes.
|
| 313 |
+
|
| 314 |
+
For unweighted graphs, the clustering of a node :math:`u`
|
| 315 |
+
is the fraction of possible triangles through that node that exist,
|
| 316 |
+
|
| 317 |
+
.. math::
|
| 318 |
+
|
| 319 |
+
c_u = \frac{2 T(u)}{deg(u)(deg(u)-1)},
|
| 320 |
+
|
| 321 |
+
where :math:`T(u)` is the number of triangles through node :math:`u` and
|
| 322 |
+
:math:`deg(u)` is the degree of :math:`u`.
|
| 323 |
+
|
| 324 |
+
For weighted graphs, there are several ways to define clustering [1]_.
|
| 325 |
+
the one used here is defined
|
| 326 |
+
as the geometric average of the subgraph edge weights [2]_,
|
| 327 |
+
|
| 328 |
+
.. math::
|
| 329 |
+
|
| 330 |
+
c_u = \frac{1}{deg(u)(deg(u)-1))}
|
| 331 |
+
\sum_{vw} (\hat{w}_{uv} \hat{w}_{uw} \hat{w}_{vw})^{1/3}.
|
| 332 |
+
|
| 333 |
+
The edge weights :math:`\hat{w}_{uv}` are normalized by the maximum weight
|
| 334 |
+
in the network :math:`\hat{w}_{uv} = w_{uv}/\max(w)`.
|
| 335 |
+
|
| 336 |
+
The value of :math:`c_u` is assigned to 0 if :math:`deg(u) < 2`.
|
| 337 |
+
|
| 338 |
+
Additionally, this weighted definition has been generalized to support negative edge weights [3]_.
|
| 339 |
+
|
| 340 |
+
For directed graphs, the clustering is similarly defined as the fraction
|
| 341 |
+
of all possible directed triangles or geometric average of the subgraph
|
| 342 |
+
edge weights for unweighted and weighted directed graph respectively [4]_.
|
| 343 |
+
|
| 344 |
+
.. math::
|
| 345 |
+
|
| 346 |
+
c_u = \frac{T(u)}{2(deg^{tot}(u)(deg^{tot}(u)-1) - 2deg^{\leftrightarrow}(u))},
|
| 347 |
+
|
| 348 |
+
where :math:`T(u)` is the number of directed triangles through node
|
| 349 |
+
:math:`u`, :math:`deg^{tot}(u)` is the sum of in degree and out degree of
|
| 350 |
+
:math:`u` and :math:`deg^{\leftrightarrow}(u)` is the reciprocal degree of
|
| 351 |
+
:math:`u`.
|
| 352 |
+
|
| 353 |
+
|
| 354 |
+
Parameters
|
| 355 |
+
----------
|
| 356 |
+
G : graph
|
| 357 |
+
|
| 358 |
+
nodes : node, iterable of nodes, or None (default=None)
|
| 359 |
+
If a singleton node, return the number of triangles for that node.
|
| 360 |
+
If an iterable, compute the number of triangles for each of those nodes.
|
| 361 |
+
If `None` (the default) compute the number of triangles for all nodes in `G`.
|
| 362 |
+
|
| 363 |
+
weight : string or None, optional (default=None)
|
| 364 |
+
The edge attribute that holds the numerical value used as a weight.
|
| 365 |
+
If None, then each edge has weight 1.
|
| 366 |
+
|
| 367 |
+
Returns
|
| 368 |
+
-------
|
| 369 |
+
out : float, or dictionary
|
| 370 |
+
Clustering coefficient at specified nodes
|
| 371 |
+
|
| 372 |
+
Examples
|
| 373 |
+
--------
|
| 374 |
+
>>> G = nx.complete_graph(5)
|
| 375 |
+
>>> print(nx.clustering(G, 0))
|
| 376 |
+
1.0
|
| 377 |
+
>>> print(nx.clustering(G))
|
| 378 |
+
{0: 1.0, 1: 1.0, 2: 1.0, 3: 1.0, 4: 1.0}
|
| 379 |
+
|
| 380 |
+
Notes
|
| 381 |
+
-----
|
| 382 |
+
Self loops are ignored.
|
| 383 |
+
|
| 384 |
+
References
|
| 385 |
+
----------
|
| 386 |
+
.. [1] Generalizations of the clustering coefficient to weighted
|
| 387 |
+
complex networks by J. Saramäki, M. Kivelä, J.-P. Onnela,
|
| 388 |
+
K. Kaski, and J. Kertész, Physical Review E, 75 027105 (2007).
|
| 389 |
+
http://jponnela.com/web_documents/a9.pdf
|
| 390 |
+
.. [2] Intensity and coherence of motifs in weighted complex
|
| 391 |
+
networks by J. P. Onnela, J. Saramäki, J. Kertész, and K. Kaski,
|
| 392 |
+
Physical Review E, 71(6), 065103 (2005).
|
| 393 |
+
.. [3] Generalization of Clustering Coefficients to Signed Correlation Networks
|
| 394 |
+
by G. Costantini and M. Perugini, PloS one, 9(2), e88669 (2014).
|
| 395 |
+
.. [4] Clustering in complex directed networks by G. Fagiolo,
|
| 396 |
+
Physical Review E, 76(2), 026107 (2007).
|
| 397 |
+
"""
|
| 398 |
+
if G.is_directed():
|
| 399 |
+
if weight is not None:
|
| 400 |
+
td_iter = _directed_weighted_triangles_and_degree_iter(G, nodes, weight)
|
| 401 |
+
clusterc = {
|
| 402 |
+
v: 0 if t == 0 else t / ((dt * (dt - 1) - 2 * db) * 2)
|
| 403 |
+
for v, dt, db, t in td_iter
|
| 404 |
+
}
|
| 405 |
+
else:
|
| 406 |
+
td_iter = _directed_triangles_and_degree_iter(G, nodes)
|
| 407 |
+
clusterc = {
|
| 408 |
+
v: 0 if t == 0 else t / ((dt * (dt - 1) - 2 * db) * 2)
|
| 409 |
+
for v, dt, db, t in td_iter
|
| 410 |
+
}
|
| 411 |
+
else:
|
| 412 |
+
# The formula 2*T/(d*(d-1)) from docs is t/(d*(d-1)) here b/c t==2*T
|
| 413 |
+
if weight is not None:
|
| 414 |
+
td_iter = _weighted_triangles_and_degree_iter(G, nodes, weight)
|
| 415 |
+
clusterc = {v: 0 if t == 0 else t / (d * (d - 1)) for v, d, t in td_iter}
|
| 416 |
+
else:
|
| 417 |
+
td_iter = _triangles_and_degree_iter(G, nodes)
|
| 418 |
+
clusterc = {v: 0 if t == 0 else t / (d * (d - 1)) for v, d, t, _ in td_iter}
|
| 419 |
+
if nodes in G:
|
| 420 |
+
# Return the value of the sole entry in the dictionary.
|
| 421 |
+
return clusterc[nodes]
|
| 422 |
+
return clusterc
|
| 423 |
+
|
| 424 |
+
|
| 425 |
+
@nx._dispatchable
|
| 426 |
+
def transitivity(G):
|
| 427 |
+
r"""Compute graph transitivity, the fraction of all possible triangles
|
| 428 |
+
present in G.
|
| 429 |
+
|
| 430 |
+
Possible triangles are identified by the number of "triads"
|
| 431 |
+
(two edges with a shared vertex).
|
| 432 |
+
|
| 433 |
+
The transitivity is
|
| 434 |
+
|
| 435 |
+
.. math::
|
| 436 |
+
|
| 437 |
+
T = 3\frac{\#triangles}{\#triads}.
|
| 438 |
+
|
| 439 |
+
Parameters
|
| 440 |
+
----------
|
| 441 |
+
G : graph
|
| 442 |
+
|
| 443 |
+
Returns
|
| 444 |
+
-------
|
| 445 |
+
out : float
|
| 446 |
+
Transitivity
|
| 447 |
+
|
| 448 |
+
Notes
|
| 449 |
+
-----
|
| 450 |
+
Self loops are ignored.
|
| 451 |
+
|
| 452 |
+
Examples
|
| 453 |
+
--------
|
| 454 |
+
>>> G = nx.complete_graph(5)
|
| 455 |
+
>>> print(nx.transitivity(G))
|
| 456 |
+
1.0
|
| 457 |
+
"""
|
| 458 |
+
triangles_contri = [
|
| 459 |
+
(t, d * (d - 1)) for v, d, t, _ in _triangles_and_degree_iter(G)
|
| 460 |
+
]
|
| 461 |
+
# If the graph is empty
|
| 462 |
+
if len(triangles_contri) == 0:
|
| 463 |
+
return 0
|
| 464 |
+
triangles, contri = map(sum, zip(*triangles_contri))
|
| 465 |
+
return 0 if triangles == 0 else triangles / contri
|
| 466 |
+
|
| 467 |
+
|
| 468 |
+
@nx._dispatchable
|
| 469 |
+
def square_clustering(G, nodes=None):
|
| 470 |
+
r"""Compute the squares clustering coefficient for nodes.
|
| 471 |
+
|
| 472 |
+
For each node return the fraction of possible squares that exist at
|
| 473 |
+
the node [1]_
|
| 474 |
+
|
| 475 |
+
.. math::
|
| 476 |
+
C_4(v) = \frac{ \sum_{u=1}^{k_v}
|
| 477 |
+
\sum_{w=u+1}^{k_v} q_v(u,w) }{ \sum_{u=1}^{k_v}
|
| 478 |
+
\sum_{w=u+1}^{k_v} [a_v(u,w) + q_v(u,w)]},
|
| 479 |
+
|
| 480 |
+
where :math:`q_v(u,w)` are the number of common neighbors of :math:`u` and
|
| 481 |
+
:math:`w` other than :math:`v` (ie squares), and :math:`a_v(u,w) = (k_u -
|
| 482 |
+
(1+q_v(u,w)+\theta_{uv})) + (k_w - (1+q_v(u,w)+\theta_{uw}))`, where
|
| 483 |
+
:math:`\theta_{uw} = 1` if :math:`u` and :math:`w` are connected and 0
|
| 484 |
+
otherwise. [2]_
|
| 485 |
+
|
| 486 |
+
Parameters
|
| 487 |
+
----------
|
| 488 |
+
G : graph
|
| 489 |
+
|
| 490 |
+
nodes : container of nodes, optional (default=all nodes in G)
|
| 491 |
+
Compute clustering for nodes in this container.
|
| 492 |
+
|
| 493 |
+
Returns
|
| 494 |
+
-------
|
| 495 |
+
c4 : dictionary
|
| 496 |
+
A dictionary keyed by node with the square clustering coefficient value.
|
| 497 |
+
|
| 498 |
+
Examples
|
| 499 |
+
--------
|
| 500 |
+
>>> G = nx.complete_graph(5)
|
| 501 |
+
>>> print(nx.square_clustering(G, 0))
|
| 502 |
+
1.0
|
| 503 |
+
>>> print(nx.square_clustering(G))
|
| 504 |
+
{0: 1.0, 1: 1.0, 2: 1.0, 3: 1.0, 4: 1.0}
|
| 505 |
+
|
| 506 |
+
Notes
|
| 507 |
+
-----
|
| 508 |
+
Self loops are ignored.
|
| 509 |
+
|
| 510 |
+
While :math:`C_3(v)` (triangle clustering) gives the probability that
|
| 511 |
+
two neighbors of node v are connected with each other, :math:`C_4(v)` is
|
| 512 |
+
the probability that two neighbors of node v share a common
|
| 513 |
+
neighbor different from v. This algorithm can be applied to both
|
| 514 |
+
bipartite and unipartite networks.
|
| 515 |
+
|
| 516 |
+
References
|
| 517 |
+
----------
|
| 518 |
+
.. [1] Pedro G. Lind, Marta C. González, and Hans J. Herrmann. 2005
|
| 519 |
+
Cycles and clustering in bipartite networks.
|
| 520 |
+
Physical Review E (72) 056127.
|
| 521 |
+
.. [2] Zhang, Peng et al. Clustering Coefficient and Community Structure of
|
| 522 |
+
Bipartite Networks. Physica A: Statistical Mechanics and its Applications 387.27 (2008): 6869–6875.
|
| 523 |
+
https://arxiv.org/abs/0710.0117v1
|
| 524 |
+
"""
|
| 525 |
+
if nodes is None:
|
| 526 |
+
node_iter = G
|
| 527 |
+
else:
|
| 528 |
+
node_iter = G.nbunch_iter(nodes)
|
| 529 |
+
clustering = {}
|
| 530 |
+
_G_adj = G._adj
|
| 531 |
+
|
| 532 |
+
class GAdj(dict):
|
| 533 |
+
"""Calculate (and cache) node neighbor sets excluding self-loops."""
|
| 534 |
+
|
| 535 |
+
def __missing__(self, v):
|
| 536 |
+
v_neighbors = self[v] = set(_G_adj[v])
|
| 537 |
+
v_neighbors.discard(v) # Ignore self-loops
|
| 538 |
+
return v_neighbors
|
| 539 |
+
|
| 540 |
+
G_adj = GAdj() # Values are sets of neighbors (no self-loops)
|
| 541 |
+
|
| 542 |
+
for v in node_iter:
|
| 543 |
+
v_neighbors = G_adj[v]
|
| 544 |
+
v_degrees_m1 = len(v_neighbors) - 1 # degrees[v] - 1 (used below)
|
| 545 |
+
if v_degrees_m1 <= 0:
|
| 546 |
+
# Can't form a square without at least two neighbors
|
| 547 |
+
clustering[v] = 0
|
| 548 |
+
continue
|
| 549 |
+
|
| 550 |
+
# Count squares with nodes u-v-w-x from the current node v.
|
| 551 |
+
# Terms of the denominator: potential = uw_degrees - uw_count - triangles - squares
|
| 552 |
+
# uw_degrees: degrees[u] + degrees[w] for each u-w combo
|
| 553 |
+
uw_degrees = 0
|
| 554 |
+
# uw_count: 1 for each u and 1 for each w for all combos (degrees * (degrees - 1))
|
| 555 |
+
uw_count = len(v_neighbors) * v_degrees_m1
|
| 556 |
+
# triangles: 1 for each edge where u-w or w-u are connected (i.e. triangles)
|
| 557 |
+
triangles = 0
|
| 558 |
+
# squares: the number of squares (also the numerator)
|
| 559 |
+
squares = 0
|
| 560 |
+
|
| 561 |
+
# Iterate over all neighbors
|
| 562 |
+
for u in v_neighbors:
|
| 563 |
+
u_neighbors = G_adj[u]
|
| 564 |
+
uw_degrees += len(u_neighbors) * v_degrees_m1
|
| 565 |
+
# P2 from https://arxiv.org/abs/2007.11111
|
| 566 |
+
p2 = len(u_neighbors & v_neighbors)
|
| 567 |
+
# triangles is C_3, sigma_4 from https://arxiv.org/abs/2007.11111
|
| 568 |
+
# This double-counts triangles compared to `triangles` function
|
| 569 |
+
triangles += p2
|
| 570 |
+
# squares is C_4, sigma_12 from https://arxiv.org/abs/2007.11111
|
| 571 |
+
# Include this term, b/c a neighbor u can also be a neighbor of neighbor x
|
| 572 |
+
squares += p2 * (p2 - 1) # Will divide by 2 later
|
| 573 |
+
|
| 574 |
+
# And iterate over all neighbors of neighbors.
|
| 575 |
+
# These nodes x may be the corners opposite v in squares u-v-w-x.
|
| 576 |
+
two_hop_neighbors = set.union(*(G_adj[u] for u in v_neighbors))
|
| 577 |
+
two_hop_neighbors -= v_neighbors # Neighbors already counted above
|
| 578 |
+
two_hop_neighbors.discard(v)
|
| 579 |
+
for x in two_hop_neighbors:
|
| 580 |
+
p2 = len(v_neighbors & G_adj[x])
|
| 581 |
+
squares += p2 * (p2 - 1) # Will divide by 2 later
|
| 582 |
+
|
| 583 |
+
squares //= 2
|
| 584 |
+
potential = uw_degrees - uw_count - triangles - squares
|
| 585 |
+
if potential > 0:
|
| 586 |
+
clustering[v] = squares / potential
|
| 587 |
+
else:
|
| 588 |
+
clustering[v] = 0
|
| 589 |
+
if nodes in G:
|
| 590 |
+
# Return the value of the sole entry in the dictionary.
|
| 591 |
+
return clustering[nodes]
|
| 592 |
+
return clustering
|
| 593 |
+
|
| 594 |
+
|
| 595 |
+
@not_implemented_for("directed")
|
| 596 |
+
@nx._dispatchable
|
| 597 |
+
def generalized_degree(G, nodes=None):
|
| 598 |
+
r"""Compute the generalized degree for nodes.
|
| 599 |
+
|
| 600 |
+
For each node, the generalized degree shows how many edges of given
|
| 601 |
+
triangle multiplicity the node is connected to. The triangle multiplicity
|
| 602 |
+
of an edge is the number of triangles an edge participates in. The
|
| 603 |
+
generalized degree of node :math:`i` can be written as a vector
|
| 604 |
+
:math:`\mathbf{k}_i=(k_i^{(0)}, \dotsc, k_i^{(N-2)})` where
|
| 605 |
+
:math:`k_i^{(j)}` is the number of edges attached to node :math:`i` that
|
| 606 |
+
participate in :math:`j` triangles.
|
| 607 |
+
|
| 608 |
+
Parameters
|
| 609 |
+
----------
|
| 610 |
+
G : graph
|
| 611 |
+
|
| 612 |
+
nodes : container of nodes, optional (default=all nodes in G)
|
| 613 |
+
Compute the generalized degree for nodes in this container.
|
| 614 |
+
|
| 615 |
+
Returns
|
| 616 |
+
-------
|
| 617 |
+
out : Counter, or dictionary of Counters
|
| 618 |
+
Generalized degree of specified nodes. The Counter is keyed by edge
|
| 619 |
+
triangle multiplicity.
|
| 620 |
+
|
| 621 |
+
Examples
|
| 622 |
+
--------
|
| 623 |
+
>>> G = nx.complete_graph(5)
|
| 624 |
+
>>> print(nx.generalized_degree(G, 0))
|
| 625 |
+
Counter({3: 4})
|
| 626 |
+
>>> print(nx.generalized_degree(G))
|
| 627 |
+
{0: Counter({3: 4}), 1: Counter({3: 4}), 2: Counter({3: 4}), 3: Counter({3: 4}), 4: Counter({3: 4})}
|
| 628 |
+
|
| 629 |
+
To recover the number of triangles attached to a node:
|
| 630 |
+
|
| 631 |
+
>>> k1 = nx.generalized_degree(G, 0)
|
| 632 |
+
>>> sum([k * v for k, v in k1.items()]) / 2 == nx.triangles(G, 0)
|
| 633 |
+
True
|
| 634 |
+
|
| 635 |
+
Notes
|
| 636 |
+
-----
|
| 637 |
+
Self loops are ignored.
|
| 638 |
+
|
| 639 |
+
In a network of N nodes, the highest triangle multiplicity an edge can have
|
| 640 |
+
is N-2.
|
| 641 |
+
|
| 642 |
+
The return value does not include a `zero` entry if no edges of a
|
| 643 |
+
particular triangle multiplicity are present.
|
| 644 |
+
|
| 645 |
+
The number of triangles node :math:`i` is attached to can be recovered from
|
| 646 |
+
the generalized degree :math:`\mathbf{k}_i=(k_i^{(0)}, \dotsc,
|
| 647 |
+
k_i^{(N-2)})` by :math:`(k_i^{(1)}+2k_i^{(2)}+\dotsc +(N-2)k_i^{(N-2)})/2`.
|
| 648 |
+
|
| 649 |
+
References
|
| 650 |
+
----------
|
| 651 |
+
.. [1] Networks with arbitrary edge multiplicities by V. Zlatić,
|
| 652 |
+
D. Garlaschelli and G. Caldarelli, EPL (Europhysics Letters),
|
| 653 |
+
Volume 97, Number 2 (2012).
|
| 654 |
+
https://iopscience.iop.org/article/10.1209/0295-5075/97/28005
|
| 655 |
+
"""
|
| 656 |
+
if nodes in G:
|
| 657 |
+
return next(_triangles_and_degree_iter(G, nodes))[3]
|
| 658 |
+
return {v: gd for v, d, t, gd in _triangles_and_degree_iter(G, nodes)}
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/communicability_alg.py
ADDED
|
@@ -0,0 +1,163 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
Communicability.
|
| 3 |
+
"""
|
| 4 |
+
|
| 5 |
+
import networkx as nx
|
| 6 |
+
from networkx.utils import not_implemented_for
|
| 7 |
+
|
| 8 |
+
__all__ = ["communicability", "communicability_exp"]
|
| 9 |
+
|
| 10 |
+
|
| 11 |
+
@not_implemented_for("directed")
|
| 12 |
+
@not_implemented_for("multigraph")
|
| 13 |
+
@nx._dispatchable
|
| 14 |
+
def communicability(G):
|
| 15 |
+
r"""Returns communicability between all pairs of nodes in G.
|
| 16 |
+
|
| 17 |
+
The communicability between pairs of nodes in G is the sum of
|
| 18 |
+
walks of different lengths starting at node u and ending at node v.
|
| 19 |
+
|
| 20 |
+
Parameters
|
| 21 |
+
----------
|
| 22 |
+
G: graph
|
| 23 |
+
|
| 24 |
+
Returns
|
| 25 |
+
-------
|
| 26 |
+
comm: dictionary of dictionaries
|
| 27 |
+
Dictionary of dictionaries keyed by nodes with communicability
|
| 28 |
+
as the value.
|
| 29 |
+
|
| 30 |
+
Raises
|
| 31 |
+
------
|
| 32 |
+
NetworkXError
|
| 33 |
+
If the graph is not undirected and simple.
|
| 34 |
+
|
| 35 |
+
See Also
|
| 36 |
+
--------
|
| 37 |
+
communicability_exp:
|
| 38 |
+
Communicability between all pairs of nodes in G using spectral
|
| 39 |
+
decomposition.
|
| 40 |
+
communicability_betweenness_centrality:
|
| 41 |
+
Communicability betweenness centrality for each node in G.
|
| 42 |
+
|
| 43 |
+
Notes
|
| 44 |
+
-----
|
| 45 |
+
This algorithm uses a spectral decomposition of the adjacency matrix.
|
| 46 |
+
Let G=(V,E) be a simple undirected graph. Using the connection between
|
| 47 |
+
the powers of the adjacency matrix and the number of walks in the graph,
|
| 48 |
+
the communicability between nodes `u` and `v` based on the graph spectrum
|
| 49 |
+
is [1]_
|
| 50 |
+
|
| 51 |
+
.. math::
|
| 52 |
+
C(u,v)=\sum_{j=1}^{n}\phi_{j}(u)\phi_{j}(v)e^{\lambda_{j}},
|
| 53 |
+
|
| 54 |
+
where `\phi_{j}(u)` is the `u\rm{th}` element of the `j\rm{th}` orthonormal
|
| 55 |
+
eigenvector of the adjacency matrix associated with the eigenvalue
|
| 56 |
+
`\lambda_{j}`.
|
| 57 |
+
|
| 58 |
+
References
|
| 59 |
+
----------
|
| 60 |
+
.. [1] Ernesto Estrada, Naomichi Hatano,
|
| 61 |
+
"Communicability in complex networks",
|
| 62 |
+
Phys. Rev. E 77, 036111 (2008).
|
| 63 |
+
https://arxiv.org/abs/0707.0756
|
| 64 |
+
|
| 65 |
+
Examples
|
| 66 |
+
--------
|
| 67 |
+
>>> G = nx.Graph([(0, 1), (1, 2), (1, 5), (5, 4), (2, 4), (2, 3), (4, 3), (3, 6)])
|
| 68 |
+
>>> c = nx.communicability(G)
|
| 69 |
+
"""
|
| 70 |
+
import numpy as np
|
| 71 |
+
|
| 72 |
+
nodelist = list(G) # ordering of nodes in matrix
|
| 73 |
+
A = nx.to_numpy_array(G, nodelist)
|
| 74 |
+
# convert to 0-1 matrix
|
| 75 |
+
A[A != 0.0] = 1
|
| 76 |
+
w, vec = np.linalg.eigh(A)
|
| 77 |
+
expw = np.exp(w)
|
| 78 |
+
mapping = dict(zip(nodelist, range(len(nodelist))))
|
| 79 |
+
c = {}
|
| 80 |
+
# computing communicabilities
|
| 81 |
+
for u in G:
|
| 82 |
+
c[u] = {}
|
| 83 |
+
for v in G:
|
| 84 |
+
s = 0
|
| 85 |
+
p = mapping[u]
|
| 86 |
+
q = mapping[v]
|
| 87 |
+
for j in range(len(nodelist)):
|
| 88 |
+
s += vec[:, j][p] * vec[:, j][q] * expw[j]
|
| 89 |
+
c[u][v] = float(s)
|
| 90 |
+
return c
|
| 91 |
+
|
| 92 |
+
|
| 93 |
+
@not_implemented_for("directed")
|
| 94 |
+
@not_implemented_for("multigraph")
|
| 95 |
+
@nx._dispatchable
|
| 96 |
+
def communicability_exp(G):
|
| 97 |
+
r"""Returns communicability between all pairs of nodes in G.
|
| 98 |
+
|
| 99 |
+
Communicability between pair of node (u,v) of node in G is the sum of
|
| 100 |
+
walks of different lengths starting at node u and ending at node v.
|
| 101 |
+
|
| 102 |
+
Parameters
|
| 103 |
+
----------
|
| 104 |
+
G: graph
|
| 105 |
+
|
| 106 |
+
Returns
|
| 107 |
+
-------
|
| 108 |
+
comm: dictionary of dictionaries
|
| 109 |
+
Dictionary of dictionaries keyed by nodes with communicability
|
| 110 |
+
as the value.
|
| 111 |
+
|
| 112 |
+
Raises
|
| 113 |
+
------
|
| 114 |
+
NetworkXError
|
| 115 |
+
If the graph is not undirected and simple.
|
| 116 |
+
|
| 117 |
+
See Also
|
| 118 |
+
--------
|
| 119 |
+
communicability:
|
| 120 |
+
Communicability between pairs of nodes in G.
|
| 121 |
+
communicability_betweenness_centrality:
|
| 122 |
+
Communicability betweenness centrality for each node in G.
|
| 123 |
+
|
| 124 |
+
Notes
|
| 125 |
+
-----
|
| 126 |
+
This algorithm uses matrix exponentiation of the adjacency matrix.
|
| 127 |
+
|
| 128 |
+
Let G=(V,E) be a simple undirected graph. Using the connection between
|
| 129 |
+
the powers of the adjacency matrix and the number of walks in the graph,
|
| 130 |
+
the communicability between nodes u and v is [1]_,
|
| 131 |
+
|
| 132 |
+
.. math::
|
| 133 |
+
C(u,v) = (e^A)_{uv},
|
| 134 |
+
|
| 135 |
+
where `A` is the adjacency matrix of G.
|
| 136 |
+
|
| 137 |
+
References
|
| 138 |
+
----------
|
| 139 |
+
.. [1] Ernesto Estrada, Naomichi Hatano,
|
| 140 |
+
"Communicability in complex networks",
|
| 141 |
+
Phys. Rev. E 77, 036111 (2008).
|
| 142 |
+
https://arxiv.org/abs/0707.0756
|
| 143 |
+
|
| 144 |
+
Examples
|
| 145 |
+
--------
|
| 146 |
+
>>> G = nx.Graph([(0, 1), (1, 2), (1, 5), (5, 4), (2, 4), (2, 3), (4, 3), (3, 6)])
|
| 147 |
+
>>> c = nx.communicability_exp(G)
|
| 148 |
+
"""
|
| 149 |
+
import scipy as sp
|
| 150 |
+
|
| 151 |
+
nodelist = list(G) # ordering of nodes in matrix
|
| 152 |
+
A = nx.to_numpy_array(G, nodelist)
|
| 153 |
+
# convert to 0-1 matrix
|
| 154 |
+
A[A != 0.0] = 1
|
| 155 |
+
# communicability matrix
|
| 156 |
+
expA = sp.linalg.expm(A)
|
| 157 |
+
mapping = dict(zip(nodelist, range(len(nodelist))))
|
| 158 |
+
c = {}
|
| 159 |
+
for u in G:
|
| 160 |
+
c[u] = {}
|
| 161 |
+
for v in G:
|
| 162 |
+
c[u][v] = float(expA[mapping[u], mapping[v]])
|
| 163 |
+
return c
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/core.py
ADDED
|
@@ -0,0 +1,588 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""
|
| 2 |
+
Find the k-cores of a graph.
|
| 3 |
+
|
| 4 |
+
The k-core is found by recursively pruning nodes with degrees less than k.
|
| 5 |
+
|
| 6 |
+
See the following references for details:
|
| 7 |
+
|
| 8 |
+
An O(m) Algorithm for Cores Decomposition of Networks
|
| 9 |
+
Vladimir Batagelj and Matjaz Zaversnik, 2003.
|
| 10 |
+
https://arxiv.org/abs/cs.DS/0310049
|
| 11 |
+
|
| 12 |
+
Generalized Cores
|
| 13 |
+
Vladimir Batagelj and Matjaz Zaversnik, 2002.
|
| 14 |
+
https://arxiv.org/pdf/cs/0202039
|
| 15 |
+
|
| 16 |
+
For directed graphs a more general notion is that of D-cores which
|
| 17 |
+
looks at (k, l) restrictions on (in, out) degree. The (k, k) D-core
|
| 18 |
+
is the k-core.
|
| 19 |
+
|
| 20 |
+
D-cores: Measuring Collaboration of Directed Graphs Based on Degeneracy
|
| 21 |
+
Christos Giatsidis, Dimitrios M. Thilikos, Michalis Vazirgiannis, ICDM 2011.
|
| 22 |
+
http://www.graphdegeneracy.org/dcores_ICDM_2011.pdf
|
| 23 |
+
|
| 24 |
+
Multi-scale structure and topological anomaly detection via a new network \
|
| 25 |
+
statistic: The onion decomposition
|
| 26 |
+
L. Hébert-Dufresne, J. A. Grochow, and A. Allard
|
| 27 |
+
Scientific Reports 6, 31708 (2016)
|
| 28 |
+
http://doi.org/10.1038/srep31708
|
| 29 |
+
|
| 30 |
+
"""
|
| 31 |
+
|
| 32 |
+
import networkx as nx
|
| 33 |
+
|
| 34 |
+
__all__ = [
|
| 35 |
+
"core_number",
|
| 36 |
+
"k_core",
|
| 37 |
+
"k_shell",
|
| 38 |
+
"k_crust",
|
| 39 |
+
"k_corona",
|
| 40 |
+
"k_truss",
|
| 41 |
+
"onion_layers",
|
| 42 |
+
]
|
| 43 |
+
|
| 44 |
+
|
| 45 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 46 |
+
@nx._dispatchable
|
| 47 |
+
def core_number(G):
|
| 48 |
+
"""Returns the core number for each node.
|
| 49 |
+
|
| 50 |
+
A k-core is a maximal subgraph that contains nodes of degree k or more.
|
| 51 |
+
|
| 52 |
+
The core number of a node is the largest value k of a k-core containing
|
| 53 |
+
that node.
|
| 54 |
+
|
| 55 |
+
Parameters
|
| 56 |
+
----------
|
| 57 |
+
G : NetworkX graph
|
| 58 |
+
An undirected or directed graph
|
| 59 |
+
|
| 60 |
+
Returns
|
| 61 |
+
-------
|
| 62 |
+
core_number : dictionary
|
| 63 |
+
A dictionary keyed by node to the core number.
|
| 64 |
+
|
| 65 |
+
Raises
|
| 66 |
+
------
|
| 67 |
+
NetworkXNotImplemented
|
| 68 |
+
If `G` is a multigraph or contains self loops.
|
| 69 |
+
|
| 70 |
+
Notes
|
| 71 |
+
-----
|
| 72 |
+
For directed graphs the node degree is defined to be the
|
| 73 |
+
in-degree + out-degree.
|
| 74 |
+
|
| 75 |
+
Examples
|
| 76 |
+
--------
|
| 77 |
+
>>> degrees = [0, 1, 2, 2, 2, 2, 3]
|
| 78 |
+
>>> H = nx.havel_hakimi_graph(degrees)
|
| 79 |
+
>>> nx.core_number(H)
|
| 80 |
+
{0: 1, 1: 2, 2: 2, 3: 2, 4: 1, 5: 2, 6: 0}
|
| 81 |
+
>>> G = nx.DiGraph()
|
| 82 |
+
>>> G.add_edges_from([(1, 2), (2, 1), (2, 3), (2, 4), (3, 4), (4, 3)])
|
| 83 |
+
>>> nx.core_number(G)
|
| 84 |
+
{1: 2, 2: 2, 3: 2, 4: 2}
|
| 85 |
+
|
| 86 |
+
References
|
| 87 |
+
----------
|
| 88 |
+
.. [1] An O(m) Algorithm for Cores Decomposition of Networks
|
| 89 |
+
Vladimir Batagelj and Matjaz Zaversnik, 2003.
|
| 90 |
+
https://arxiv.org/abs/cs.DS/0310049
|
| 91 |
+
"""
|
| 92 |
+
if nx.number_of_selfloops(G) > 0:
|
| 93 |
+
msg = (
|
| 94 |
+
"Input graph has self loops which is not permitted; "
|
| 95 |
+
"Consider using G.remove_edges_from(nx.selfloop_edges(G))."
|
| 96 |
+
)
|
| 97 |
+
raise nx.NetworkXNotImplemented(msg)
|
| 98 |
+
degrees = dict(G.degree())
|
| 99 |
+
# Sort nodes by degree.
|
| 100 |
+
nodes = sorted(degrees, key=degrees.get)
|
| 101 |
+
bin_boundaries = [0]
|
| 102 |
+
curr_degree = 0
|
| 103 |
+
for i, v in enumerate(nodes):
|
| 104 |
+
if degrees[v] > curr_degree:
|
| 105 |
+
bin_boundaries.extend([i] * (degrees[v] - curr_degree))
|
| 106 |
+
curr_degree = degrees[v]
|
| 107 |
+
node_pos = {v: pos for pos, v in enumerate(nodes)}
|
| 108 |
+
# The initial guess for the core number of a node is its degree.
|
| 109 |
+
core = degrees
|
| 110 |
+
nbrs = {v: list(nx.all_neighbors(G, v)) for v in G}
|
| 111 |
+
for v in nodes:
|
| 112 |
+
for u in nbrs[v]:
|
| 113 |
+
if core[u] > core[v]:
|
| 114 |
+
nbrs[u].remove(v)
|
| 115 |
+
pos = node_pos[u]
|
| 116 |
+
bin_start = bin_boundaries[core[u]]
|
| 117 |
+
node_pos[u] = bin_start
|
| 118 |
+
node_pos[nodes[bin_start]] = pos
|
| 119 |
+
nodes[bin_start], nodes[pos] = nodes[pos], nodes[bin_start]
|
| 120 |
+
bin_boundaries[core[u]] += 1
|
| 121 |
+
core[u] -= 1
|
| 122 |
+
return core
|
| 123 |
+
|
| 124 |
+
|
| 125 |
+
def _core_subgraph(G, k_filter, k=None, core=None):
|
| 126 |
+
"""Returns the subgraph induced by nodes passing filter `k_filter`.
|
| 127 |
+
|
| 128 |
+
Parameters
|
| 129 |
+
----------
|
| 130 |
+
G : NetworkX graph
|
| 131 |
+
The graph or directed graph to process
|
| 132 |
+
k_filter : filter function
|
| 133 |
+
This function filters the nodes chosen. It takes three inputs:
|
| 134 |
+
A node of G, the filter's cutoff, and the core dict of the graph.
|
| 135 |
+
The function should return a Boolean value.
|
| 136 |
+
k : int, optional
|
| 137 |
+
The order of the core. If not specified use the max core number.
|
| 138 |
+
This value is used as the cutoff for the filter.
|
| 139 |
+
core : dict, optional
|
| 140 |
+
Precomputed core numbers keyed by node for the graph `G`.
|
| 141 |
+
If not specified, the core numbers will be computed from `G`.
|
| 142 |
+
|
| 143 |
+
"""
|
| 144 |
+
if core is None:
|
| 145 |
+
core = core_number(G)
|
| 146 |
+
if k is None:
|
| 147 |
+
k = max(core.values())
|
| 148 |
+
nodes = (v for v in core if k_filter(v, k, core))
|
| 149 |
+
return G.subgraph(nodes).copy()
|
| 150 |
+
|
| 151 |
+
|
| 152 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 153 |
+
@nx._dispatchable(preserve_all_attrs=True, returns_graph=True)
|
| 154 |
+
def k_core(G, k=None, core_number=None):
|
| 155 |
+
"""Returns the k-core of G.
|
| 156 |
+
|
| 157 |
+
A k-core is a maximal subgraph that contains nodes of degree `k` or more.
|
| 158 |
+
|
| 159 |
+
Parameters
|
| 160 |
+
----------
|
| 161 |
+
G : NetworkX graph
|
| 162 |
+
A graph or directed graph
|
| 163 |
+
k : int, optional
|
| 164 |
+
The order of the core. If not specified return the main core.
|
| 165 |
+
core_number : dictionary, optional
|
| 166 |
+
Precomputed core numbers for the graph G.
|
| 167 |
+
|
| 168 |
+
Returns
|
| 169 |
+
-------
|
| 170 |
+
G : NetworkX graph
|
| 171 |
+
The k-core subgraph
|
| 172 |
+
|
| 173 |
+
Raises
|
| 174 |
+
------
|
| 175 |
+
NetworkXNotImplemented
|
| 176 |
+
The k-core is not defined for multigraphs or graphs with self loops.
|
| 177 |
+
|
| 178 |
+
Notes
|
| 179 |
+
-----
|
| 180 |
+
The main core is the core with `k` as the largest core_number.
|
| 181 |
+
|
| 182 |
+
For directed graphs the node degree is defined to be the
|
| 183 |
+
in-degree + out-degree.
|
| 184 |
+
|
| 185 |
+
Graph, node, and edge attributes are copied to the subgraph.
|
| 186 |
+
|
| 187 |
+
Examples
|
| 188 |
+
--------
|
| 189 |
+
>>> degrees = [0, 1, 2, 2, 2, 2, 3]
|
| 190 |
+
>>> H = nx.havel_hakimi_graph(degrees)
|
| 191 |
+
>>> H.degree
|
| 192 |
+
DegreeView({0: 1, 1: 2, 2: 2, 3: 2, 4: 2, 5: 3, 6: 0})
|
| 193 |
+
>>> nx.k_core(H).nodes
|
| 194 |
+
NodeView((1, 2, 3, 5))
|
| 195 |
+
|
| 196 |
+
See Also
|
| 197 |
+
--------
|
| 198 |
+
core_number
|
| 199 |
+
|
| 200 |
+
References
|
| 201 |
+
----------
|
| 202 |
+
.. [1] An O(m) Algorithm for Cores Decomposition of Networks
|
| 203 |
+
Vladimir Batagelj and Matjaz Zaversnik, 2003.
|
| 204 |
+
https://arxiv.org/abs/cs.DS/0310049
|
| 205 |
+
"""
|
| 206 |
+
|
| 207 |
+
def k_filter(v, k, c):
|
| 208 |
+
return c[v] >= k
|
| 209 |
+
|
| 210 |
+
return _core_subgraph(G, k_filter, k, core_number)
|
| 211 |
+
|
| 212 |
+
|
| 213 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 214 |
+
@nx._dispatchable(preserve_all_attrs=True, returns_graph=True)
|
| 215 |
+
def k_shell(G, k=None, core_number=None):
|
| 216 |
+
"""Returns the k-shell of G.
|
| 217 |
+
|
| 218 |
+
The k-shell is the subgraph induced by nodes with core number k.
|
| 219 |
+
That is, nodes in the k-core that are not in the (k+1)-core.
|
| 220 |
+
|
| 221 |
+
Parameters
|
| 222 |
+
----------
|
| 223 |
+
G : NetworkX graph
|
| 224 |
+
A graph or directed graph.
|
| 225 |
+
k : int, optional
|
| 226 |
+
The order of the shell. If not specified return the outer shell.
|
| 227 |
+
core_number : dictionary, optional
|
| 228 |
+
Precomputed core numbers for the graph G.
|
| 229 |
+
|
| 230 |
+
|
| 231 |
+
Returns
|
| 232 |
+
-------
|
| 233 |
+
G : NetworkX graph
|
| 234 |
+
The k-shell subgraph
|
| 235 |
+
|
| 236 |
+
Raises
|
| 237 |
+
------
|
| 238 |
+
NetworkXNotImplemented
|
| 239 |
+
The k-shell is not implemented for multigraphs or graphs with self loops.
|
| 240 |
+
|
| 241 |
+
Notes
|
| 242 |
+
-----
|
| 243 |
+
This is similar to k_corona but in that case only neighbors in the
|
| 244 |
+
k-core are considered.
|
| 245 |
+
|
| 246 |
+
For directed graphs the node degree is defined to be the
|
| 247 |
+
in-degree + out-degree.
|
| 248 |
+
|
| 249 |
+
Graph, node, and edge attributes are copied to the subgraph.
|
| 250 |
+
|
| 251 |
+
Examples
|
| 252 |
+
--------
|
| 253 |
+
>>> degrees = [0, 1, 2, 2, 2, 2, 3]
|
| 254 |
+
>>> H = nx.havel_hakimi_graph(degrees)
|
| 255 |
+
>>> H.degree
|
| 256 |
+
DegreeView({0: 1, 1: 2, 2: 2, 3: 2, 4: 2, 5: 3, 6: 0})
|
| 257 |
+
>>> nx.k_shell(H, k=1).nodes
|
| 258 |
+
NodeView((0, 4))
|
| 259 |
+
|
| 260 |
+
See Also
|
| 261 |
+
--------
|
| 262 |
+
core_number
|
| 263 |
+
k_corona
|
| 264 |
+
|
| 265 |
+
|
| 266 |
+
References
|
| 267 |
+
----------
|
| 268 |
+
.. [1] A model of Internet topology using k-shell decomposition
|
| 269 |
+
Shai Carmi, Shlomo Havlin, Scott Kirkpatrick, Yuval Shavitt,
|
| 270 |
+
and Eran Shir, PNAS July 3, 2007 vol. 104 no. 27 11150-11154
|
| 271 |
+
http://www.pnas.org/content/104/27/11150.full
|
| 272 |
+
"""
|
| 273 |
+
|
| 274 |
+
def k_filter(v, k, c):
|
| 275 |
+
return c[v] == k
|
| 276 |
+
|
| 277 |
+
return _core_subgraph(G, k_filter, k, core_number)
|
| 278 |
+
|
| 279 |
+
|
| 280 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 281 |
+
@nx._dispatchable(preserve_all_attrs=True, returns_graph=True)
|
| 282 |
+
def k_crust(G, k=None, core_number=None):
|
| 283 |
+
"""Returns the k-crust of G.
|
| 284 |
+
|
| 285 |
+
The k-crust is the graph G with the edges of the k-core removed
|
| 286 |
+
and isolated nodes found after the removal of edges are also removed.
|
| 287 |
+
|
| 288 |
+
Parameters
|
| 289 |
+
----------
|
| 290 |
+
G : NetworkX graph
|
| 291 |
+
A graph or directed graph.
|
| 292 |
+
k : int, optional
|
| 293 |
+
The order of the shell. If not specified return the main crust.
|
| 294 |
+
core_number : dictionary, optional
|
| 295 |
+
Precomputed core numbers for the graph G.
|
| 296 |
+
|
| 297 |
+
Returns
|
| 298 |
+
-------
|
| 299 |
+
G : NetworkX graph
|
| 300 |
+
The k-crust subgraph
|
| 301 |
+
|
| 302 |
+
Raises
|
| 303 |
+
------
|
| 304 |
+
NetworkXNotImplemented
|
| 305 |
+
The k-crust is not implemented for multigraphs or graphs with self loops.
|
| 306 |
+
|
| 307 |
+
Notes
|
| 308 |
+
-----
|
| 309 |
+
This definition of k-crust is different than the definition in [1]_.
|
| 310 |
+
The k-crust in [1]_ is equivalent to the k+1 crust of this algorithm.
|
| 311 |
+
|
| 312 |
+
For directed graphs the node degree is defined to be the
|
| 313 |
+
in-degree + out-degree.
|
| 314 |
+
|
| 315 |
+
Graph, node, and edge attributes are copied to the subgraph.
|
| 316 |
+
|
| 317 |
+
Examples
|
| 318 |
+
--------
|
| 319 |
+
>>> degrees = [0, 1, 2, 2, 2, 2, 3]
|
| 320 |
+
>>> H = nx.havel_hakimi_graph(degrees)
|
| 321 |
+
>>> H.degree
|
| 322 |
+
DegreeView({0: 1, 1: 2, 2: 2, 3: 2, 4: 2, 5: 3, 6: 0})
|
| 323 |
+
>>> nx.k_crust(H, k=1).nodes
|
| 324 |
+
NodeView((0, 4, 6))
|
| 325 |
+
|
| 326 |
+
See Also
|
| 327 |
+
--------
|
| 328 |
+
core_number
|
| 329 |
+
|
| 330 |
+
References
|
| 331 |
+
----------
|
| 332 |
+
.. [1] A model of Internet topology using k-shell decomposition
|
| 333 |
+
Shai Carmi, Shlomo Havlin, Scott Kirkpatrick, Yuval Shavitt,
|
| 334 |
+
and Eran Shir, PNAS July 3, 2007 vol. 104 no. 27 11150-11154
|
| 335 |
+
http://www.pnas.org/content/104/27/11150.full
|
| 336 |
+
"""
|
| 337 |
+
# Default for k is one less than in _core_subgraph, so just inline.
|
| 338 |
+
# Filter is c[v] <= k
|
| 339 |
+
if core_number is None:
|
| 340 |
+
core_number = nx.core_number(G)
|
| 341 |
+
if k is None:
|
| 342 |
+
k = max(core_number.values()) - 1
|
| 343 |
+
nodes = (v for v in core_number if core_number[v] <= k)
|
| 344 |
+
return G.subgraph(nodes).copy()
|
| 345 |
+
|
| 346 |
+
|
| 347 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 348 |
+
@nx._dispatchable(preserve_all_attrs=True, returns_graph=True)
|
| 349 |
+
def k_corona(G, k, core_number=None):
|
| 350 |
+
"""Returns the k-corona of G.
|
| 351 |
+
|
| 352 |
+
The k-corona is the subgraph of nodes in the k-core which have
|
| 353 |
+
exactly k neighbors in the k-core.
|
| 354 |
+
|
| 355 |
+
Parameters
|
| 356 |
+
----------
|
| 357 |
+
G : NetworkX graph
|
| 358 |
+
A graph or directed graph
|
| 359 |
+
k : int
|
| 360 |
+
The order of the corona.
|
| 361 |
+
core_number : dictionary, optional
|
| 362 |
+
Precomputed core numbers for the graph G.
|
| 363 |
+
|
| 364 |
+
Returns
|
| 365 |
+
-------
|
| 366 |
+
G : NetworkX graph
|
| 367 |
+
The k-corona subgraph
|
| 368 |
+
|
| 369 |
+
Raises
|
| 370 |
+
------
|
| 371 |
+
NetworkXNotImplemented
|
| 372 |
+
The k-corona is not defined for multigraphs or graphs with self loops.
|
| 373 |
+
|
| 374 |
+
Notes
|
| 375 |
+
-----
|
| 376 |
+
For directed graphs the node degree is defined to be the
|
| 377 |
+
in-degree + out-degree.
|
| 378 |
+
|
| 379 |
+
Graph, node, and edge attributes are copied to the subgraph.
|
| 380 |
+
|
| 381 |
+
Examples
|
| 382 |
+
--------
|
| 383 |
+
>>> degrees = [0, 1, 2, 2, 2, 2, 3]
|
| 384 |
+
>>> H = nx.havel_hakimi_graph(degrees)
|
| 385 |
+
>>> H.degree
|
| 386 |
+
DegreeView({0: 1, 1: 2, 2: 2, 3: 2, 4: 2, 5: 3, 6: 0})
|
| 387 |
+
>>> nx.k_corona(H, k=2).nodes
|
| 388 |
+
NodeView((1, 2, 3, 5))
|
| 389 |
+
|
| 390 |
+
See Also
|
| 391 |
+
--------
|
| 392 |
+
core_number
|
| 393 |
+
|
| 394 |
+
References
|
| 395 |
+
----------
|
| 396 |
+
.. [1] k -core (bootstrap) percolation on complex networks:
|
| 397 |
+
Critical phenomena and nonlocal effects,
|
| 398 |
+
A. V. Goltsev, S. N. Dorogovtsev, and J. F. F. Mendes,
|
| 399 |
+
Phys. Rev. E 73, 056101 (2006)
|
| 400 |
+
http://link.aps.org/doi/10.1103/PhysRevE.73.056101
|
| 401 |
+
"""
|
| 402 |
+
|
| 403 |
+
def func(v, k, c):
|
| 404 |
+
return c[v] == k and k == sum(1 for w in G[v] if c[w] >= k)
|
| 405 |
+
|
| 406 |
+
return _core_subgraph(G, func, k, core_number)
|
| 407 |
+
|
| 408 |
+
|
| 409 |
+
@nx.utils.not_implemented_for("directed")
|
| 410 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 411 |
+
@nx._dispatchable(preserve_all_attrs=True, returns_graph=True)
|
| 412 |
+
def k_truss(G, k):
|
| 413 |
+
"""Returns the k-truss of `G`.
|
| 414 |
+
|
| 415 |
+
The k-truss is the maximal induced subgraph of `G` which contains at least
|
| 416 |
+
three vertices where every edge is incident to at least `k-2` triangles.
|
| 417 |
+
|
| 418 |
+
Parameters
|
| 419 |
+
----------
|
| 420 |
+
G : NetworkX graph
|
| 421 |
+
An undirected graph
|
| 422 |
+
k : int
|
| 423 |
+
The order of the truss
|
| 424 |
+
|
| 425 |
+
Returns
|
| 426 |
+
-------
|
| 427 |
+
H : NetworkX graph
|
| 428 |
+
The k-truss subgraph
|
| 429 |
+
|
| 430 |
+
Raises
|
| 431 |
+
------
|
| 432 |
+
NetworkXNotImplemented
|
| 433 |
+
If `G` is a multigraph or directed graph or if it contains self loops.
|
| 434 |
+
|
| 435 |
+
Notes
|
| 436 |
+
-----
|
| 437 |
+
A k-clique is a (k-2)-truss and a k-truss is a (k+1)-core.
|
| 438 |
+
|
| 439 |
+
Graph, node, and edge attributes are copied to the subgraph.
|
| 440 |
+
|
| 441 |
+
K-trusses were originally defined in [2] which states that the k-truss
|
| 442 |
+
is the maximal induced subgraph where each edge belongs to at least
|
| 443 |
+
`k-2` triangles. A more recent paper, [1], uses a slightly different
|
| 444 |
+
definition requiring that each edge belong to at least `k` triangles.
|
| 445 |
+
This implementation uses the original definition of `k-2` triangles.
|
| 446 |
+
|
| 447 |
+
Examples
|
| 448 |
+
--------
|
| 449 |
+
>>> degrees = [0, 1, 2, 2, 2, 2, 3]
|
| 450 |
+
>>> H = nx.havel_hakimi_graph(degrees)
|
| 451 |
+
>>> H.degree
|
| 452 |
+
DegreeView({0: 1, 1: 2, 2: 2, 3: 2, 4: 2, 5: 3, 6: 0})
|
| 453 |
+
>>> nx.k_truss(H, k=2).nodes
|
| 454 |
+
NodeView((0, 1, 2, 3, 4, 5))
|
| 455 |
+
|
| 456 |
+
References
|
| 457 |
+
----------
|
| 458 |
+
.. [1] Bounds and Algorithms for k-truss. Paul Burkhardt, Vance Faber,
|
| 459 |
+
David G. Harris, 2018. https://arxiv.org/abs/1806.05523v2
|
| 460 |
+
.. [2] Trusses: Cohesive Subgraphs for Social Network Analysis. Jonathan
|
| 461 |
+
Cohen, 2005.
|
| 462 |
+
"""
|
| 463 |
+
if nx.number_of_selfloops(G) > 0:
|
| 464 |
+
msg = (
|
| 465 |
+
"Input graph has self loops which is not permitted; "
|
| 466 |
+
"Consider using G.remove_edges_from(nx.selfloop_edges(G))."
|
| 467 |
+
)
|
| 468 |
+
raise nx.NetworkXNotImplemented(msg)
|
| 469 |
+
|
| 470 |
+
H = G.copy()
|
| 471 |
+
|
| 472 |
+
n_dropped = 1
|
| 473 |
+
while n_dropped > 0:
|
| 474 |
+
n_dropped = 0
|
| 475 |
+
to_drop = []
|
| 476 |
+
seen = set()
|
| 477 |
+
for u in H:
|
| 478 |
+
nbrs_u = set(H[u])
|
| 479 |
+
seen.add(u)
|
| 480 |
+
new_nbrs = [v for v in nbrs_u if v not in seen]
|
| 481 |
+
for v in new_nbrs:
|
| 482 |
+
if len(nbrs_u & set(H[v])) < (k - 2):
|
| 483 |
+
to_drop.append((u, v))
|
| 484 |
+
H.remove_edges_from(to_drop)
|
| 485 |
+
n_dropped = len(to_drop)
|
| 486 |
+
H.remove_nodes_from(list(nx.isolates(H)))
|
| 487 |
+
|
| 488 |
+
return H
|
| 489 |
+
|
| 490 |
+
|
| 491 |
+
@nx.utils.not_implemented_for("multigraph")
|
| 492 |
+
@nx.utils.not_implemented_for("directed")
|
| 493 |
+
@nx._dispatchable
|
| 494 |
+
def onion_layers(G):
|
| 495 |
+
"""Returns the layer of each vertex in an onion decomposition of the graph.
|
| 496 |
+
|
| 497 |
+
The onion decomposition refines the k-core decomposition by providing
|
| 498 |
+
information on the internal organization of each k-shell. It is usually
|
| 499 |
+
used alongside the `core numbers`.
|
| 500 |
+
|
| 501 |
+
Parameters
|
| 502 |
+
----------
|
| 503 |
+
G : NetworkX graph
|
| 504 |
+
An undirected graph without self loops.
|
| 505 |
+
|
| 506 |
+
Returns
|
| 507 |
+
-------
|
| 508 |
+
od_layers : dictionary
|
| 509 |
+
A dictionary keyed by node to the onion layer. The layers are
|
| 510 |
+
contiguous integers starting at 1.
|
| 511 |
+
|
| 512 |
+
Raises
|
| 513 |
+
------
|
| 514 |
+
NetworkXNotImplemented
|
| 515 |
+
If `G` is a multigraph or directed graph or if it contains self loops.
|
| 516 |
+
|
| 517 |
+
Examples
|
| 518 |
+
--------
|
| 519 |
+
>>> degrees = [0, 1, 2, 2, 2, 2, 3]
|
| 520 |
+
>>> H = nx.havel_hakimi_graph(degrees)
|
| 521 |
+
>>> H.degree
|
| 522 |
+
DegreeView({0: 1, 1: 2, 2: 2, 3: 2, 4: 2, 5: 3, 6: 0})
|
| 523 |
+
>>> nx.onion_layers(H)
|
| 524 |
+
{6: 1, 0: 2, 4: 3, 1: 4, 2: 4, 3: 4, 5: 4}
|
| 525 |
+
|
| 526 |
+
See Also
|
| 527 |
+
--------
|
| 528 |
+
core_number
|
| 529 |
+
|
| 530 |
+
References
|
| 531 |
+
----------
|
| 532 |
+
.. [1] Multi-scale structure and topological anomaly detection via a new
|
| 533 |
+
network statistic: The onion decomposition
|
| 534 |
+
L. Hébert-Dufresne, J. A. Grochow, and A. Allard
|
| 535 |
+
Scientific Reports 6, 31708 (2016)
|
| 536 |
+
http://doi.org/10.1038/srep31708
|
| 537 |
+
.. [2] Percolation and the effective structure of complex networks
|
| 538 |
+
A. Allard and L. Hébert-Dufresne
|
| 539 |
+
Physical Review X 9, 011023 (2019)
|
| 540 |
+
http://doi.org/10.1103/PhysRevX.9.011023
|
| 541 |
+
"""
|
| 542 |
+
if nx.number_of_selfloops(G) > 0:
|
| 543 |
+
msg = (
|
| 544 |
+
"Input graph contains self loops which is not permitted; "
|
| 545 |
+
"Consider using G.remove_edges_from(nx.selfloop_edges(G))."
|
| 546 |
+
)
|
| 547 |
+
raise nx.NetworkXNotImplemented(msg)
|
| 548 |
+
# Dictionaries to register the k-core/onion decompositions.
|
| 549 |
+
od_layers = {}
|
| 550 |
+
# Adjacency list
|
| 551 |
+
neighbors = {v: list(nx.all_neighbors(G, v)) for v in G}
|
| 552 |
+
# Effective degree of nodes.
|
| 553 |
+
degrees = dict(G.degree())
|
| 554 |
+
# Performs the onion decomposition.
|
| 555 |
+
current_core = 1
|
| 556 |
+
current_layer = 1
|
| 557 |
+
# Sets vertices of degree 0 to layer 1, if any.
|
| 558 |
+
isolated_nodes = list(nx.isolates(G))
|
| 559 |
+
if len(isolated_nodes) > 0:
|
| 560 |
+
for v in isolated_nodes:
|
| 561 |
+
od_layers[v] = current_layer
|
| 562 |
+
degrees.pop(v)
|
| 563 |
+
current_layer = 2
|
| 564 |
+
# Finds the layer for the remaining nodes.
|
| 565 |
+
while len(degrees) > 0:
|
| 566 |
+
# Sets the order for looking at nodes.
|
| 567 |
+
nodes = sorted(degrees, key=degrees.get)
|
| 568 |
+
# Sets properly the current core.
|
| 569 |
+
min_degree = degrees[nodes[0]]
|
| 570 |
+
if min_degree > current_core:
|
| 571 |
+
current_core = min_degree
|
| 572 |
+
# Identifies vertices in the current layer.
|
| 573 |
+
this_layer = []
|
| 574 |
+
for n in nodes:
|
| 575 |
+
if degrees[n] > current_core:
|
| 576 |
+
break
|
| 577 |
+
this_layer.append(n)
|
| 578 |
+
# Identifies the core/layer of the vertices in the current layer.
|
| 579 |
+
for v in this_layer:
|
| 580 |
+
od_layers[v] = current_layer
|
| 581 |
+
for n in neighbors[v]:
|
| 582 |
+
neighbors[n].remove(v)
|
| 583 |
+
degrees[n] = degrees[n] - 1
|
| 584 |
+
degrees.pop(v)
|
| 585 |
+
# Updates the layer count.
|
| 586 |
+
current_layer = current_layer + 1
|
| 587 |
+
# Returns the dictionaries containing the onion layer of each vertices.
|
| 588 |
+
return od_layers
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/covering.py
ADDED
|
@@ -0,0 +1,142 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions related to graph covers."""
|
| 2 |
+
|
| 3 |
+
from functools import partial
|
| 4 |
+
from itertools import chain
|
| 5 |
+
|
| 6 |
+
import networkx as nx
|
| 7 |
+
from networkx.utils import arbitrary_element, not_implemented_for
|
| 8 |
+
|
| 9 |
+
__all__ = ["min_edge_cover", "is_edge_cover"]
|
| 10 |
+
|
| 11 |
+
|
| 12 |
+
@not_implemented_for("directed")
|
| 13 |
+
@not_implemented_for("multigraph")
|
| 14 |
+
@nx._dispatchable
|
| 15 |
+
def min_edge_cover(G, matching_algorithm=None):
|
| 16 |
+
"""Returns the min cardinality edge cover of the graph as a set of edges.
|
| 17 |
+
|
| 18 |
+
A smallest edge cover can be found in polynomial time by finding
|
| 19 |
+
a maximum matching and extending it greedily so that all nodes
|
| 20 |
+
are covered. This function follows that process. A maximum matching
|
| 21 |
+
algorithm can be specified for the first step of the algorithm.
|
| 22 |
+
The resulting set may return a set with one 2-tuple for each edge,
|
| 23 |
+
(the usual case) or with both 2-tuples `(u, v)` and `(v, u)` for
|
| 24 |
+
each edge. The latter is only done when a bipartite matching algorithm
|
| 25 |
+
is specified as `matching_algorithm`.
|
| 26 |
+
|
| 27 |
+
Parameters
|
| 28 |
+
----------
|
| 29 |
+
G : NetworkX graph
|
| 30 |
+
An undirected graph.
|
| 31 |
+
|
| 32 |
+
matching_algorithm : function
|
| 33 |
+
A function that returns a maximum cardinality matching for `G`.
|
| 34 |
+
The function must take one input, the graph `G`, and return
|
| 35 |
+
either a set of edges (with only one direction for the pair of nodes)
|
| 36 |
+
or a dictionary mapping each node to its mate. If not specified,
|
| 37 |
+
:func:`~networkx.algorithms.matching.max_weight_matching` is used.
|
| 38 |
+
Common bipartite matching functions include
|
| 39 |
+
:func:`~networkx.algorithms.bipartite.matching.hopcroft_karp_matching`
|
| 40 |
+
or
|
| 41 |
+
:func:`~networkx.algorithms.bipartite.matching.eppstein_matching`.
|
| 42 |
+
|
| 43 |
+
Returns
|
| 44 |
+
-------
|
| 45 |
+
min_cover : set
|
| 46 |
+
|
| 47 |
+
A set of the edges in a minimum edge cover in the form of tuples.
|
| 48 |
+
It contains only one of the equivalent 2-tuples `(u, v)` and `(v, u)`
|
| 49 |
+
for each edge. If a bipartite method is used to compute the matching,
|
| 50 |
+
the returned set contains both the 2-tuples `(u, v)` and `(v, u)`
|
| 51 |
+
for each edge of a minimum edge cover.
|
| 52 |
+
|
| 53 |
+
Examples
|
| 54 |
+
--------
|
| 55 |
+
>>> G = nx.Graph([(0, 1), (0, 2), (0, 3), (1, 2), (1, 3)])
|
| 56 |
+
>>> sorted(nx.min_edge_cover(G))
|
| 57 |
+
[(2, 1), (3, 0)]
|
| 58 |
+
|
| 59 |
+
Notes
|
| 60 |
+
-----
|
| 61 |
+
An edge cover of a graph is a set of edges such that every node of
|
| 62 |
+
the graph is incident to at least one edge of the set.
|
| 63 |
+
The minimum edge cover is an edge covering of smallest cardinality.
|
| 64 |
+
|
| 65 |
+
Due to its implementation, the worst-case running time of this algorithm
|
| 66 |
+
is bounded by the worst-case running time of the function
|
| 67 |
+
``matching_algorithm``.
|
| 68 |
+
|
| 69 |
+
Minimum edge cover for `G` can also be found using
|
| 70 |
+
:func:`~networkx.algorithms.bipartite.covering.min_edge_covering` which is
|
| 71 |
+
simply this function with a default matching algorithm of
|
| 72 |
+
:func:`~networkx.algorithms.bipartite.matching.hopcroft_karp_matching`
|
| 73 |
+
"""
|
| 74 |
+
if len(G) == 0:
|
| 75 |
+
return set()
|
| 76 |
+
if nx.number_of_isolates(G) > 0:
|
| 77 |
+
# ``min_cover`` does not exist as there is an isolated node
|
| 78 |
+
raise nx.NetworkXException(
|
| 79 |
+
"Graph has a node with no edge incident on it, so no edge cover exists."
|
| 80 |
+
)
|
| 81 |
+
if matching_algorithm is None:
|
| 82 |
+
matching_algorithm = partial(nx.max_weight_matching, maxcardinality=True)
|
| 83 |
+
maximum_matching = matching_algorithm(G)
|
| 84 |
+
# ``min_cover`` is superset of ``maximum_matching``
|
| 85 |
+
try:
|
| 86 |
+
# bipartite matching algs return dict so convert if needed
|
| 87 |
+
min_cover = set(maximum_matching.items())
|
| 88 |
+
bipartite_cover = True
|
| 89 |
+
except AttributeError:
|
| 90 |
+
min_cover = maximum_matching
|
| 91 |
+
bipartite_cover = False
|
| 92 |
+
# iterate for uncovered nodes
|
| 93 |
+
uncovered_nodes = set(G) - {v for u, v in min_cover} - {u for u, v in min_cover}
|
| 94 |
+
for v in uncovered_nodes:
|
| 95 |
+
# Since `v` is uncovered, each edge incident to `v` will join it
|
| 96 |
+
# with a covered node (otherwise, if there were an edge joining
|
| 97 |
+
# uncovered nodes `u` and `v`, the maximum matching algorithm
|
| 98 |
+
# would have found it), so we can choose an arbitrary edge
|
| 99 |
+
# incident to `v`. (This applies only in a simple graph, not a
|
| 100 |
+
# multigraph.)
|
| 101 |
+
u = arbitrary_element(G[v])
|
| 102 |
+
min_cover.add((u, v))
|
| 103 |
+
if bipartite_cover:
|
| 104 |
+
min_cover.add((v, u))
|
| 105 |
+
return min_cover
|
| 106 |
+
|
| 107 |
+
|
| 108 |
+
@not_implemented_for("directed")
|
| 109 |
+
@nx._dispatchable
|
| 110 |
+
def is_edge_cover(G, cover):
|
| 111 |
+
"""Decides whether a set of edges is a valid edge cover of the graph.
|
| 112 |
+
|
| 113 |
+
Given a set of edges, whether it is an edge covering can
|
| 114 |
+
be decided if we just check whether all nodes of the graph
|
| 115 |
+
has an edge from the set, incident on it.
|
| 116 |
+
|
| 117 |
+
Parameters
|
| 118 |
+
----------
|
| 119 |
+
G : NetworkX graph
|
| 120 |
+
An undirected bipartite graph.
|
| 121 |
+
|
| 122 |
+
cover : set
|
| 123 |
+
Set of edges to be checked.
|
| 124 |
+
|
| 125 |
+
Returns
|
| 126 |
+
-------
|
| 127 |
+
bool
|
| 128 |
+
Whether the set of edges is a valid edge cover of the graph.
|
| 129 |
+
|
| 130 |
+
Examples
|
| 131 |
+
--------
|
| 132 |
+
>>> G = nx.Graph([(0, 1), (0, 2), (0, 3), (1, 2), (1, 3)])
|
| 133 |
+
>>> cover = {(2, 1), (3, 0)}
|
| 134 |
+
>>> nx.is_edge_cover(G, cover)
|
| 135 |
+
True
|
| 136 |
+
|
| 137 |
+
Notes
|
| 138 |
+
-----
|
| 139 |
+
An edge cover of a graph is a set of edges such that every node of
|
| 140 |
+
the graph is incident to at least one edge of the set.
|
| 141 |
+
"""
|
| 142 |
+
return set(G) <= set(chain.from_iterable(cover))
|
tool_server/.venv/lib/python3.12/site-packages/networkx/algorithms/cuts.py
ADDED
|
@@ -0,0 +1,398 @@
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1 |
+
"""Functions for finding and evaluating cuts in a graph."""
|
| 2 |
+
|
| 3 |
+
from itertools import chain
|
| 4 |
+
|
| 5 |
+
import networkx as nx
|
| 6 |
+
|
| 7 |
+
__all__ = [
|
| 8 |
+
"boundary_expansion",
|
| 9 |
+
"conductance",
|
| 10 |
+
"cut_size",
|
| 11 |
+
"edge_expansion",
|
| 12 |
+
"mixing_expansion",
|
| 13 |
+
"node_expansion",
|
| 14 |
+
"normalized_cut_size",
|
| 15 |
+
"volume",
|
| 16 |
+
]
|
| 17 |
+
|
| 18 |
+
|
| 19 |
+
# TODO STILL NEED TO UPDATE ALL THE DOCUMENTATION!
|
| 20 |
+
|
| 21 |
+
|
| 22 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 23 |
+
def cut_size(G, S, T=None, weight=None):
|
| 24 |
+
"""Returns the size of the cut between two sets of nodes.
|
| 25 |
+
|
| 26 |
+
A *cut* is a partition of the nodes of a graph into two sets. The
|
| 27 |
+
*cut size* is the sum of the weights of the edges "between" the two
|
| 28 |
+
sets of nodes.
|
| 29 |
+
|
| 30 |
+
Parameters
|
| 31 |
+
----------
|
| 32 |
+
G : NetworkX graph
|
| 33 |
+
|
| 34 |
+
S : collection
|
| 35 |
+
A collection of nodes in `G`.
|
| 36 |
+
|
| 37 |
+
T : collection
|
| 38 |
+
A collection of nodes in `G`. If not specified, this is taken to
|
| 39 |
+
be the set complement of `S`.
|
| 40 |
+
|
| 41 |
+
weight : object
|
| 42 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 43 |
+
have weight one.
|
| 44 |
+
|
| 45 |
+
Returns
|
| 46 |
+
-------
|
| 47 |
+
number
|
| 48 |
+
Total weight of all edges from nodes in set `S` to nodes in
|
| 49 |
+
set `T` (and, in the case of directed graphs, all edges from
|
| 50 |
+
nodes in `T` to nodes in `S`).
|
| 51 |
+
|
| 52 |
+
Examples
|
| 53 |
+
--------
|
| 54 |
+
In the graph with two cliques joined by a single edges, the natural
|
| 55 |
+
bipartition of the graph into two blocks, one for each clique,
|
| 56 |
+
yields a cut of weight one::
|
| 57 |
+
|
| 58 |
+
>>> G = nx.barbell_graph(3, 0)
|
| 59 |
+
>>> S = {0, 1, 2}
|
| 60 |
+
>>> T = {3, 4, 5}
|
| 61 |
+
>>> nx.cut_size(G, S, T)
|
| 62 |
+
1
|
| 63 |
+
|
| 64 |
+
Each parallel edge in a multigraph is counted when determining the
|
| 65 |
+
cut size::
|
| 66 |
+
|
| 67 |
+
>>> G = nx.MultiGraph(["ab", "ab"])
|
| 68 |
+
>>> S = {"a"}
|
| 69 |
+
>>> T = {"b"}
|
| 70 |
+
>>> nx.cut_size(G, S, T)
|
| 71 |
+
2
|
| 72 |
+
|
| 73 |
+
Notes
|
| 74 |
+
-----
|
| 75 |
+
In a multigraph, the cut size is the total weight of edges including
|
| 76 |
+
multiplicity.
|
| 77 |
+
|
| 78 |
+
"""
|
| 79 |
+
edges = nx.edge_boundary(G, S, T, data=weight, default=1)
|
| 80 |
+
if G.is_directed():
|
| 81 |
+
edges = chain(edges, nx.edge_boundary(G, T, S, data=weight, default=1))
|
| 82 |
+
return sum(weight for u, v, weight in edges)
|
| 83 |
+
|
| 84 |
+
|
| 85 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 86 |
+
def volume(G, S, weight=None):
|
| 87 |
+
"""Returns the volume of a set of nodes.
|
| 88 |
+
|
| 89 |
+
The *volume* of a set *S* is the sum of the (out-)degrees of nodes
|
| 90 |
+
in *S* (taking into account parallel edges in multigraphs). [1]
|
| 91 |
+
|
| 92 |
+
Parameters
|
| 93 |
+
----------
|
| 94 |
+
G : NetworkX graph
|
| 95 |
+
|
| 96 |
+
S : collection
|
| 97 |
+
A collection of nodes in `G`.
|
| 98 |
+
|
| 99 |
+
weight : object
|
| 100 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 101 |
+
have weight one.
|
| 102 |
+
|
| 103 |
+
Returns
|
| 104 |
+
-------
|
| 105 |
+
number
|
| 106 |
+
The volume of the set of nodes represented by `S` in the graph
|
| 107 |
+
`G`.
|
| 108 |
+
|
| 109 |
+
See also
|
| 110 |
+
--------
|
| 111 |
+
conductance
|
| 112 |
+
cut_size
|
| 113 |
+
edge_expansion
|
| 114 |
+
edge_boundary
|
| 115 |
+
normalized_cut_size
|
| 116 |
+
|
| 117 |
+
References
|
| 118 |
+
----------
|
| 119 |
+
.. [1] David Gleich.
|
| 120 |
+
*Hierarchical Directed Spectral Graph Partitioning*.
|
| 121 |
+
<https://www.cs.purdue.edu/homes/dgleich/publications/Gleich%202005%20-%20hierarchical%20directed%20spectral.pdf>
|
| 122 |
+
|
| 123 |
+
"""
|
| 124 |
+
degree = G.out_degree if G.is_directed() else G.degree
|
| 125 |
+
return sum(d for v, d in degree(S, weight=weight))
|
| 126 |
+
|
| 127 |
+
|
| 128 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 129 |
+
def normalized_cut_size(G, S, T=None, weight=None):
|
| 130 |
+
"""Returns the normalized size of the cut between two sets of nodes.
|
| 131 |
+
|
| 132 |
+
The *normalized cut size* is the cut size times the sum of the
|
| 133 |
+
reciprocal sizes of the volumes of the two sets. [1]
|
| 134 |
+
|
| 135 |
+
Parameters
|
| 136 |
+
----------
|
| 137 |
+
G : NetworkX graph
|
| 138 |
+
|
| 139 |
+
S : collection
|
| 140 |
+
A collection of nodes in `G`.
|
| 141 |
+
|
| 142 |
+
T : collection
|
| 143 |
+
A collection of nodes in `G`.
|
| 144 |
+
|
| 145 |
+
weight : object
|
| 146 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 147 |
+
have weight one.
|
| 148 |
+
|
| 149 |
+
Returns
|
| 150 |
+
-------
|
| 151 |
+
number
|
| 152 |
+
The normalized cut size between the two sets `S` and `T`.
|
| 153 |
+
|
| 154 |
+
Notes
|
| 155 |
+
-----
|
| 156 |
+
In a multigraph, the cut size is the total weight of edges including
|
| 157 |
+
multiplicity.
|
| 158 |
+
|
| 159 |
+
See also
|
| 160 |
+
--------
|
| 161 |
+
conductance
|
| 162 |
+
cut_size
|
| 163 |
+
edge_expansion
|
| 164 |
+
volume
|
| 165 |
+
|
| 166 |
+
References
|
| 167 |
+
----------
|
| 168 |
+
.. [1] David Gleich.
|
| 169 |
+
*Hierarchical Directed Spectral Graph Partitioning*.
|
| 170 |
+
<https://www.cs.purdue.edu/homes/dgleich/publications/Gleich%202005%20-%20hierarchical%20directed%20spectral.pdf>
|
| 171 |
+
|
| 172 |
+
"""
|
| 173 |
+
if T is None:
|
| 174 |
+
T = set(G) - set(S)
|
| 175 |
+
num_cut_edges = cut_size(G, S, T=T, weight=weight)
|
| 176 |
+
volume_S = volume(G, S, weight=weight)
|
| 177 |
+
volume_T = volume(G, T, weight=weight)
|
| 178 |
+
return num_cut_edges * ((1 / volume_S) + (1 / volume_T))
|
| 179 |
+
|
| 180 |
+
|
| 181 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 182 |
+
def conductance(G, S, T=None, weight=None):
|
| 183 |
+
"""Returns the conductance of two sets of nodes.
|
| 184 |
+
|
| 185 |
+
The *conductance* is the quotient of the cut size and the smaller of
|
| 186 |
+
the volumes of the two sets. [1]
|
| 187 |
+
|
| 188 |
+
Parameters
|
| 189 |
+
----------
|
| 190 |
+
G : NetworkX graph
|
| 191 |
+
|
| 192 |
+
S : collection
|
| 193 |
+
A collection of nodes in `G`.
|
| 194 |
+
|
| 195 |
+
T : collection
|
| 196 |
+
A collection of nodes in `G`.
|
| 197 |
+
|
| 198 |
+
weight : object
|
| 199 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 200 |
+
have weight one.
|
| 201 |
+
|
| 202 |
+
Returns
|
| 203 |
+
-------
|
| 204 |
+
number
|
| 205 |
+
The conductance between the two sets `S` and `T`.
|
| 206 |
+
|
| 207 |
+
See also
|
| 208 |
+
--------
|
| 209 |
+
cut_size
|
| 210 |
+
edge_expansion
|
| 211 |
+
normalized_cut_size
|
| 212 |
+
volume
|
| 213 |
+
|
| 214 |
+
References
|
| 215 |
+
----------
|
| 216 |
+
.. [1] David Gleich.
|
| 217 |
+
*Hierarchical Directed Spectral Graph Partitioning*.
|
| 218 |
+
<https://www.cs.purdue.edu/homes/dgleich/publications/Gleich%202005%20-%20hierarchical%20directed%20spectral.pdf>
|
| 219 |
+
|
| 220 |
+
"""
|
| 221 |
+
if T is None:
|
| 222 |
+
T = set(G) - set(S)
|
| 223 |
+
num_cut_edges = cut_size(G, S, T, weight=weight)
|
| 224 |
+
volume_S = volume(G, S, weight=weight)
|
| 225 |
+
volume_T = volume(G, T, weight=weight)
|
| 226 |
+
return num_cut_edges / min(volume_S, volume_T)
|
| 227 |
+
|
| 228 |
+
|
| 229 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 230 |
+
def edge_expansion(G, S, T=None, weight=None):
|
| 231 |
+
"""Returns the edge expansion between two node sets.
|
| 232 |
+
|
| 233 |
+
The *edge expansion* is the quotient of the cut size and the smaller
|
| 234 |
+
of the cardinalities of the two sets. [1]
|
| 235 |
+
|
| 236 |
+
Parameters
|
| 237 |
+
----------
|
| 238 |
+
G : NetworkX graph
|
| 239 |
+
|
| 240 |
+
S : collection
|
| 241 |
+
A collection of nodes in `G`.
|
| 242 |
+
|
| 243 |
+
T : collection
|
| 244 |
+
A collection of nodes in `G`.
|
| 245 |
+
|
| 246 |
+
weight : object
|
| 247 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 248 |
+
have weight one.
|
| 249 |
+
|
| 250 |
+
Returns
|
| 251 |
+
-------
|
| 252 |
+
number
|
| 253 |
+
The edge expansion between the two sets `S` and `T`.
|
| 254 |
+
|
| 255 |
+
See also
|
| 256 |
+
--------
|
| 257 |
+
boundary_expansion
|
| 258 |
+
mixing_expansion
|
| 259 |
+
node_expansion
|
| 260 |
+
|
| 261 |
+
References
|
| 262 |
+
----------
|
| 263 |
+
.. [1] Fan Chung.
|
| 264 |
+
*Spectral Graph Theory*.
|
| 265 |
+
(CBMS Regional Conference Series in Mathematics, No. 92),
|
| 266 |
+
American Mathematical Society, 1997, ISBN 0-8218-0315-8
|
| 267 |
+
<http://www.math.ucsd.edu/~fan/research/revised.html>
|
| 268 |
+
|
| 269 |
+
"""
|
| 270 |
+
if T is None:
|
| 271 |
+
T = set(G) - set(S)
|
| 272 |
+
num_cut_edges = cut_size(G, S, T=T, weight=weight)
|
| 273 |
+
return num_cut_edges / min(len(S), len(T))
|
| 274 |
+
|
| 275 |
+
|
| 276 |
+
@nx._dispatchable(edge_attrs="weight")
|
| 277 |
+
def mixing_expansion(G, S, T=None, weight=None):
|
| 278 |
+
"""Returns the mixing expansion between two node sets.
|
| 279 |
+
|
| 280 |
+
The *mixing expansion* is the quotient of the cut size and twice the
|
| 281 |
+
number of edges in the graph. [1]
|
| 282 |
+
|
| 283 |
+
Parameters
|
| 284 |
+
----------
|
| 285 |
+
G : NetworkX graph
|
| 286 |
+
|
| 287 |
+
S : collection
|
| 288 |
+
A collection of nodes in `G`.
|
| 289 |
+
|
| 290 |
+
T : collection
|
| 291 |
+
A collection of nodes in `G`.
|
| 292 |
+
|
| 293 |
+
weight : object
|
| 294 |
+
Edge attribute key to use as weight. If not specified, edges
|
| 295 |
+
have weight one.
|
| 296 |
+
|
| 297 |
+
Returns
|
| 298 |
+
-------
|
| 299 |
+
number
|
| 300 |
+
The mixing expansion between the two sets `S` and `T`.
|
| 301 |
+
|
| 302 |
+
See also
|
| 303 |
+
--------
|
| 304 |
+
boundary_expansion
|
| 305 |
+
edge_expansion
|
| 306 |
+
node_expansion
|
| 307 |
+
|
| 308 |
+
References
|
| 309 |
+
----------
|
| 310 |
+
.. [1] Vadhan, Salil P.
|
| 311 |
+
"Pseudorandomness."
|
| 312 |
+
*Foundations and Trends
|
| 313 |
+
in Theoretical Computer Science* 7.1–3 (2011): 1–336.
|
| 314 |
+
<https://doi.org/10.1561/0400000010>
|
| 315 |
+
|
| 316 |
+
"""
|
| 317 |
+
num_cut_edges = cut_size(G, S, T=T, weight=weight)
|
| 318 |
+
num_total_edges = G.number_of_edges()
|
| 319 |
+
return num_cut_edges / (2 * num_total_edges)
|
| 320 |
+
|
| 321 |
+
|
| 322 |
+
# TODO What is the generalization to two arguments, S and T? Does the
|
| 323 |
+
# denominator become `min(len(S), len(T))`?
|
| 324 |
+
@nx._dispatchable
|
| 325 |
+
def node_expansion(G, S):
|
| 326 |
+
"""Returns the node expansion of the set `S`.
|
| 327 |
+
|
| 328 |
+
The *node expansion* is the quotient of the size of the node
|
| 329 |
+
boundary of *S* and the cardinality of *S*. [1]
|
| 330 |
+
|
| 331 |
+
Parameters
|
| 332 |
+
----------
|
| 333 |
+
G : NetworkX graph
|
| 334 |
+
|
| 335 |
+
S : collection
|
| 336 |
+
A collection of nodes in `G`.
|
| 337 |
+
|
| 338 |
+
Returns
|
| 339 |
+
-------
|
| 340 |
+
number
|
| 341 |
+
The node expansion of the set `S`.
|
| 342 |
+
|
| 343 |
+
See also
|
| 344 |
+
--------
|
| 345 |
+
boundary_expansion
|
| 346 |
+
edge_expansion
|
| 347 |
+
mixing_expansion
|
| 348 |
+
|
| 349 |
+
References
|
| 350 |
+
----------
|
| 351 |
+
.. [1] Vadhan, Salil P.
|
| 352 |
+
"Pseudorandomness."
|
| 353 |
+
*Foundations and Trends
|
| 354 |
+
in Theoretical Computer Science* 7.1–3 (2011): 1–336.
|
| 355 |
+
<https://doi.org/10.1561/0400000010>
|
| 356 |
+
|
| 357 |
+
"""
|
| 358 |
+
neighborhood = set(chain.from_iterable(G.neighbors(v) for v in S))
|
| 359 |
+
return len(neighborhood) / len(S)
|
| 360 |
+
|
| 361 |
+
|
| 362 |
+
# TODO What is the generalization to two arguments, S and T? Does the
|
| 363 |
+
# denominator become `min(len(S), len(T))`?
|
| 364 |
+
@nx._dispatchable
|
| 365 |
+
def boundary_expansion(G, S):
|
| 366 |
+
"""Returns the boundary expansion of the set `S`.
|
| 367 |
+
|
| 368 |
+
The *boundary expansion* is the quotient of the size
|
| 369 |
+
of the node boundary and the cardinality of *S*. [1]
|
| 370 |
+
|
| 371 |
+
Parameters
|
| 372 |
+
----------
|
| 373 |
+
G : NetworkX graph
|
| 374 |
+
|
| 375 |
+
S : collection
|
| 376 |
+
A collection of nodes in `G`.
|
| 377 |
+
|
| 378 |
+
Returns
|
| 379 |
+
-------
|
| 380 |
+
number
|
| 381 |
+
The boundary expansion of the set `S`.
|
| 382 |
+
|
| 383 |
+
See also
|
| 384 |
+
--------
|
| 385 |
+
edge_expansion
|
| 386 |
+
mixing_expansion
|
| 387 |
+
node_expansion
|
| 388 |
+
|
| 389 |
+
References
|
| 390 |
+
----------
|
| 391 |
+
.. [1] Vadhan, Salil P.
|
| 392 |
+
"Pseudorandomness."
|
| 393 |
+
*Foundations and Trends in Theoretical Computer Science*
|
| 394 |
+
7.1–3 (2011): 1–336.
|
| 395 |
+
<https://doi.org/10.1561/0400000010>
|
| 396 |
+
|
| 397 |
+
"""
|
| 398 |
+
return len(nx.node_boundary(G, S)) / len(S)
|