| |
| |
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| |
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|
|
| """Classes and methods for finding consensus trees. |
| |
| This module contains a ``_BitString`` class to assist the consensus tree |
| searching and some common consensus algorithms such as strict, majority rule and |
| adam consensus. |
| """ |
|
|
| import itertools |
| import random |
| from ast import literal_eval |
|
|
| from Bio.Align import MultipleSeqAlignment |
| from Bio.Phylo import BaseTree |
|
|
|
|
| class _BitString(str): |
| """Helper class for binary string data (PRIVATE). |
| |
| Assistant class of binary string data used for storing and |
| counting compatible clades in consensus tree searching. It includes |
| some binary manipulation(&|^~) methods. |
| |
| _BitString is a sub-class of ``str`` object that only accepts two |
| characters('0' and '1'), with additional functions for binary-like |
| manipulation(&|^~). It is used to count and store the clades in |
| multiple trees in consensus tree searching. During counting, the |
| clades will be considered the same if their terminals(in terms of |
| ``name`` attribute) are the same. |
| |
| For example, let's say two trees are provided as below to search |
| their strict consensus tree:: |
| |
| tree1: (((A, B), C),(D, E)) |
| tree2: ((A, (B, C)),(D, E)) |
| |
| For both trees, a _BitString object '11111' will represent their |
| root clade. Each '1' stands for the terminal clade in the list |
| [A, B, C, D, E](the order might not be the same, it's determined |
| by the ``get_terminal`` method of the first tree provided). For |
| the clade ((A, B), C) in tree1 and (A, (B, C)) in tree2, they both |
| can be represented by '11100'. Similarly, '11000' represents clade |
| (A, B) in tree1, '01100' represents clade (B, C) in tree2, and '00011' |
| represents clade (D, E) in both trees. |
| |
| So, with the ``_count_clades`` function in this module, finally we |
| can get the clade counts and their _BitString representation as follows |
| (the root and terminals are omitted):: |
| |
| clade _BitString count |
| ABC '11100' 2 |
| DE '00011' 2 |
| AB '11000' 1 |
| BC '01100' 1 |
| |
| To get the _BitString representation of a clade, we can use the following |
| code snippet:: |
| |
| # suppose we are provided with a tree list, the first thing to do is |
| # to get all the terminal names in the first tree |
| term_names = [term.name for term in trees[0].get_terminals()] |
| # for a specific clade in any of the tree, also get its terminal names |
| clade_term_names = [term.name for term in clade.get_terminals()] |
| # then create a boolean list |
| boolvals = [name in clade_term_names for name in term_names] |
| # create the string version and pass it to _BitString |
| bitstr = _BitString(''.join(map(str, map(int, boolvals)))) |
| # or, equivalently: |
| bitstr = _BitString.from_bool(boolvals) |
| |
| To convert back:: |
| |
| # get all the terminal clades of the first tree |
| terms = [term for term in trees[0].get_terminals()] |
| # get the index of terminal clades in bitstr |
| index_list = bitstr.index_one() |
| # get all terminal clades by index |
| clade_terms = [terms[i] for i in index_list] |
| # create a new calde and append all the terminal clades |
| new_clade = BaseTree.Clade() |
| new_clade.clades.extend(clade_terms) |
| |
| Examples |
| -------- |
| >>> from Bio.Phylo.Consensus import _BitString |
| >>> bitstr1 = _BitString('11111') |
| >>> bitstr2 = _BitString('11100') |
| >>> bitstr3 = _BitString('01101') |
| >>> bitstr1 |
| _BitString('11111') |
| >>> bitstr2 & bitstr3 |
| _BitString('01100') |
| >>> bitstr2 | bitstr3 |
| _BitString('11101') |
| >>> bitstr2 ^ bitstr3 |
| _BitString('10001') |
| >>> bitstr2.index_one() |
| [0, 1, 2] |
| >>> bitstr3.index_one() |
| [1, 2, 4] |
| >>> bitstr3.index_zero() |
| [0, 3] |
| >>> bitstr1.contains(bitstr2) |
| True |
| >>> bitstr2.contains(bitstr3) |
| False |
| >>> bitstr2.independent(bitstr3) |
| False |
| >>> bitstr1.iscompatible(bitstr2) |
| True |
| >>> bitstr2.iscompatible(bitstr3) |
| False |
| |
| """ |
|
|
| def __new__(cls, strdata): |
| """Init from a binary string data.""" |
| if isinstance(strdata, str) and len(strdata) == strdata.count( |
| "0" |
| ) + strdata.count("1"): |
| return str.__new__(cls, strdata) |
| else: |
| raise TypeError( |
| "The input should be a binary string composed of '0' and '1'" |
| ) |
|
|
| def __and__(self, other): |
| selfint = literal_eval("0b" + self) |
| otherint = literal_eval("0b" + other) |
| resultint = selfint & otherint |
| return _BitString(bin(resultint)[2:].zfill(len(self))) |
|
|
| def __or__(self, other): |
| selfint = literal_eval("0b" + self) |
| otherint = literal_eval("0b" + other) |
| resultint = selfint | otherint |
| return _BitString(bin(resultint)[2:].zfill(len(self))) |
|
|
| def __xor__(self, other): |
| selfint = literal_eval("0b" + self) |
| otherint = literal_eval("0b" + other) |
| resultint = selfint ^ otherint |
| return _BitString(bin(resultint)[2:].zfill(len(self))) |
|
|
| def __rand__(self, other): |
| selfint = literal_eval("0b" + self) |
| otherint = literal_eval("0b" + other) |
| resultint = otherint & selfint |
| return _BitString(bin(resultint)[2:].zfill(len(self))) |
|
|
| def __ror__(self, other): |
| selfint = literal_eval("0b" + self) |
| otherint = literal_eval("0b" + other) |
| resultint = otherint | selfint |
| return _BitString(bin(resultint)[2:].zfill(len(self))) |
|
|
| def __rxor__(self, other): |
| selfint = literal_eval("0b" + self) |
| otherint = literal_eval("0b" + other) |
| resultint = otherint ^ selfint |
| return _BitString(bin(resultint)[2:].zfill(len(self))) |
|
|
| def __repr__(self): |
| return "_BitString(" + str.__repr__(self) + ")" |
|
|
| def index_one(self): |
| """Return a list of positions where the element is '1'.""" |
| return [i for i, n in enumerate(self) if n == "1"] |
|
|
| def index_zero(self): |
| """Return a list of positions where the element is '0'.""" |
| return [i for i, n in enumerate(self) if n == "0"] |
|
|
| def contains(self, other): |
| """Check if current bitstr1 contains another one bitstr2. |
| |
| That is to say, the bitstr2.index_one() is a subset of |
| bitstr1.index_one(). |
| |
| Examples: |
| "011011" contains "011000", "011001", "000011" |
| |
| Be careful, "011011" also contains "000000". Actually, all _BitString |
| objects contain all-zero _BitString of the same length. |
| |
| """ |
| xorbit = self ^ other |
| return xorbit.count("1") == self.count("1") - other.count("1") |
|
|
| def independent(self, other): |
| """Check if current bitstr1 is independent of another one bitstr2. |
| |
| That is to say the bitstr1.index_one() and bitstr2.index_one() have |
| no intersection. |
| |
| Be careful, all _BitString objects are independent of all-zero _BitString |
| of the same length. |
| """ |
| xorbit = self ^ other |
| return xorbit.count("1") == self.count("1") + other.count("1") |
|
|
| def iscompatible(self, other): |
| """Check if current bitstr1 is compatible with another bitstr2. |
| |
| Two conditions are considered as compatible: |
| 1. bitstr1.contain(bitstr2) or vice versa; |
| 2. bitstr1.independent(bitstr2). |
| |
| """ |
| return self.contains(other) or other.contains(self) or self.independent(other) |
|
|
| @classmethod |
| def from_bool(cls, bools): |
| return cls("".join(map(str, map(int, bools)))) |
|
|
|
|
| def strict_consensus(trees): |
| """Search strict consensus tree from multiple trees. |
| |
| :Parameters: |
| trees : iterable |
| iterable of trees to produce consensus tree. |
| |
| """ |
| trees_iter = iter(trees) |
| first_tree = next(trees_iter) |
|
|
| terms = first_tree.get_terminals() |
| bitstr_counts, tree_count = _count_clades(itertools.chain([first_tree], trees_iter)) |
|
|
| |
| strict_bitstrs = [ |
| bitstr for bitstr, t in bitstr_counts.items() if t[0] == tree_count |
| ] |
| strict_bitstrs.sort(key=lambda bitstr: bitstr.count("1"), reverse=True) |
| |
| root = BaseTree.Clade() |
| if strict_bitstrs[0].count("1") == len(terms): |
| root.clades.extend(terms) |
| else: |
| raise ValueError("Taxons in provided trees should be consistent") |
| |
| bitstr_clades = {strict_bitstrs[0]: root} |
| |
| for bitstr in strict_bitstrs[1:]: |
| clade_terms = [terms[i] for i in bitstr.index_one()] |
| clade = BaseTree.Clade() |
| clade.clades.extend(clade_terms) |
| for bs, c in bitstr_clades.items(): |
| |
| if bs.contains(bitstr): |
| |
| del bitstr_clades[bs] |
| |
| c.clades = [child for child in c.clades if child not in clade_terms] |
| |
| c.clades.append(clade) |
| |
| bs = bs ^ bitstr |
| |
| bitstr_clades[bs] = c |
| break |
| |
| bitstr_clades[bitstr] = clade |
| return BaseTree.Tree(root=root) |
|
|
|
|
| def majority_consensus(trees, cutoff=0): |
| """Search majority rule consensus tree from multiple trees. |
| |
| This is an extend majority rule method, which means the you can set any |
| cutoff between 0 ~ 1 instead of 0.5. The default value of cutoff is 0 to |
| create a relaxed binary consensus tree in any condition (as long as one of |
| the provided trees is a binary tree). The branch length of each consensus |
| clade in the result consensus tree is the average length of all counts for |
| that clade. |
| |
| :Parameters: |
| trees : iterable |
| iterable of trees to produce consensus tree. |
| |
| """ |
| tree_iter = iter(trees) |
| first_tree = next(tree_iter) |
|
|
| terms = first_tree.get_terminals() |
| bitstr_counts, tree_count = _count_clades(itertools.chain([first_tree], tree_iter)) |
|
|
| |
| bitstrs = sorted( |
| bitstr_counts.keys(), |
| key=lambda bitstr: (bitstr_counts[bitstr][0], bitstr.count("1"), str(bitstr)), |
| reverse=True, |
| ) |
| root = BaseTree.Clade() |
| if bitstrs[0].count("1") == len(terms): |
| root.clades.extend(terms) |
| else: |
| raise ValueError("Taxons in provided trees should be consistent") |
| |
| bitstr_clades = {bitstrs[0]: root} |
| |
| for bitstr in bitstrs[1:]: |
| |
| count_in_trees, branch_length_sum = bitstr_counts[bitstr] |
| confidence = 100.0 * count_in_trees / tree_count |
| if confidence < cutoff * 100.0: |
| break |
| clade_terms = [terms[i] for i in bitstr.index_one()] |
| clade = BaseTree.Clade() |
| clade.clades.extend(clade_terms) |
| clade.confidence = confidence |
| clade.branch_length = branch_length_sum / count_in_trees |
| bsckeys = sorted(bitstr_clades, key=lambda bs: bs.count("1"), reverse=True) |
|
|
| |
| |
| compatible = True |
| parent_bitstr = None |
| child_bitstrs = [] |
| for bs in bsckeys: |
| if not bs.iscompatible(bitstr): |
| compatible = False |
| break |
| |
| |
| if bs.contains(bitstr): |
| parent_bitstr = bs |
| |
| |
| if ( |
| bitstr.contains(bs) |
| and bs != bitstr |
| and all(c.independent(bs) for c in child_bitstrs) |
| ): |
| child_bitstrs.append(bs) |
| if not compatible: |
| continue |
|
|
| if parent_bitstr: |
| |
| parent_clade = bitstr_clades.pop(parent_bitstr) |
| |
| parent_clade.clades = [ |
| c for c in parent_clade.clades if c not in clade_terms |
| ] |
| |
| parent_clade.clades.append(clade) |
| |
| |
| |
| bitstr_clades[parent_bitstr] = parent_clade |
|
|
| if child_bitstrs: |
| remove_list = [] |
| for c in child_bitstrs: |
| remove_list.extend(c.index_one()) |
| child_clade = bitstr_clades[c] |
| parent_clade.clades.remove(child_clade) |
| clade.clades.append(child_clade) |
| remove_terms = [terms[i] for i in remove_list] |
| clade.clades = [c for c in clade.clades if c not in remove_terms] |
| |
| bitstr_clades[bitstr] = clade |
| if (len(bitstr_clades) == len(terms) - 1) or ( |
| len(bitstr_clades) == len(terms) - 2 and len(root.clades) == 3 |
| ): |
| break |
| return BaseTree.Tree(root=root) |
|
|
|
|
| def adam_consensus(trees): |
| """Search Adam Consensus tree from multiple trees. |
| |
| :Parameters: |
| trees : list |
| list of trees to produce consensus tree. |
| |
| """ |
| clades = [tree.root for tree in trees] |
| return BaseTree.Tree(root=_part(clades), rooted=True) |
|
|
|
|
| def _part(clades): |
| """Recursive function for Adam Consensus algorithm (PRIVATE).""" |
| new_clade = None |
| terms = clades[0].get_terminals() |
| term_names = [term.name for term in terms] |
| if len(terms) == 1 or len(terms) == 2: |
| new_clade = clades[0] |
| else: |
| bitstrs = {_BitString("1" * len(terms))} |
| for clade in clades: |
| for child in clade.clades: |
| bitstr = _clade_to_bitstr(child, term_names) |
| to_remove = set() |
| to_add = set() |
| for bs in bitstrs: |
| if bs == bitstr: |
| continue |
| elif bs.contains(bitstr): |
| to_add.add(bitstr) |
| to_add.add(bs ^ bitstr) |
| to_remove.add(bs) |
| elif bitstr.contains(bs): |
| to_add.add(bs ^ bitstr) |
| elif not bs.independent(bitstr): |
| to_add.add(bs & bitstr) |
| to_add.add(bs & bitstr ^ bitstr) |
| to_add.add(bs & bitstr ^ bs) |
| to_remove.add(bs) |
| |
| bitstrs ^= to_remove |
| if to_add: |
| for ta in sorted(to_add, key=lambda bs: bs.count("1")): |
| independent = True |
| for bs in bitstrs: |
| if not ta.independent(bs): |
| independent = False |
| break |
| if independent: |
| bitstrs.add(ta) |
| new_clade = BaseTree.Clade() |
| for bitstr in sorted(bitstrs): |
| indices = bitstr.index_one() |
| if len(indices) == 1: |
| new_clade.clades.append(terms[indices[0]]) |
| elif len(indices) == 2: |
| bifur_clade = BaseTree.Clade() |
| bifur_clade.clades.append(terms[indices[0]]) |
| bifur_clade.clades.append(terms[indices[1]]) |
| new_clade.clades.append(bifur_clade) |
| elif len(indices) > 2: |
| part_names = [term_names[i] for i in indices] |
| next_clades = [] |
| for clade in clades: |
| next_clades.append(_sub_clade(clade, part_names)) |
| |
| new_clade.clades.append(_part(next_clades)) |
| return new_clade |
|
|
|
|
| def _sub_clade(clade, term_names): |
| """Extract a compatible subclade that only contains the given terminal names (PRIVATE).""" |
| term_clades = [clade.find_any(name) for name in term_names] |
| sub_clade = clade.common_ancestor(term_clades) |
| if len(term_names) != sub_clade.count_terminals(): |
| temp_clade = BaseTree.Clade() |
| temp_clade.clades.extend(term_clades) |
| for c in sub_clade.find_clades(terminal=False, order="preorder"): |
| if c == sub_clade.root: |
| continue |
| children = set(c.find_clades(terminal=True)) & set(term_clades) |
| if children: |
| for tc in temp_clade.find_clades(terminal=False, order="preorder"): |
| tc_children = set(tc.clades) |
| tc_new_clades = tc_children - children |
| if children.issubset(tc_children) and tc_new_clades: |
| tc.clades = list(tc_new_clades) |
| child_clade = BaseTree.Clade() |
| child_clade.clades.extend(list(children)) |
| tc.clades.append(child_clade) |
| sub_clade = temp_clade |
| return sub_clade |
|
|
|
|
| def _count_clades(trees): |
| """Count distinct clades (different sets of terminal names) in the trees (PRIVATE). |
| |
| Return a tuple first a dict of bitstring (representing clade) and a tuple of its count of |
| occurrences and sum of branch length for that clade, second the number of trees processed. |
| |
| :Parameters: |
| trees : iterable |
| An iterable that returns the trees to count |
| |
| """ |
| bitstrs = {} |
| tree_count = 0 |
| for tree in trees: |
| tree_count += 1 |
| clade_bitstrs = _tree_to_bitstrs(tree) |
| for clade in tree.find_clades(terminal=False): |
| bitstr = clade_bitstrs[clade] |
| if bitstr in bitstrs: |
| count, sum_bl = bitstrs[bitstr] |
| count += 1 |
| sum_bl += clade.branch_length or 0 |
| bitstrs[bitstr] = (count, sum_bl) |
| else: |
| bitstrs[bitstr] = (1, clade.branch_length or 0) |
| return bitstrs, tree_count |
|
|
|
|
| def get_support(target_tree, trees, len_trees=None): |
| """Calculate branch support for a target tree given bootstrap replicate trees. |
| |
| :Parameters: |
| target_tree : Tree |
| tree to calculate branch support for. |
| trees : iterable |
| iterable of trees used to calculate branch support. |
| len_trees : int |
| optional count of replicates in trees. len_trees must be provided |
| when len(trees) is not a valid operation. |
| |
| """ |
| term_names = sorted(term.name for term in target_tree.find_clades(terminal=True)) |
| bitstrs = {} |
|
|
| size = len_trees |
| if size is None: |
| try: |
| size = len(trees) |
| except TypeError: |
| raise TypeError( |
| "Trees does not support len(trees), " |
| "you must provide the number of replicates in trees " |
| "as the optional parameter len_trees." |
| ) from None |
|
|
| for clade in target_tree.find_clades(terminal=False): |
| bitstr = _clade_to_bitstr(clade, term_names) |
| bitstrs[bitstr] = (clade, 0) |
| for tree in trees: |
| for clade in tree.find_clades(terminal=False): |
| bitstr = _clade_to_bitstr(clade, term_names) |
| if bitstr in bitstrs: |
| c, t = bitstrs[bitstr] |
| c.confidence = (t + 1) * 100.0 / size |
| bitstrs[bitstr] = (c, t + 1) |
| return target_tree |
|
|
|
|
| def bootstrap(msa, times): |
| """Generate bootstrap replicates from a multiple sequence alignment (OBSOLETE). |
| |
| :Parameters: |
| msa : MultipleSeqAlignment |
| multiple sequence alignment to generate replicates. |
| times : int |
| number of bootstrap times. |
| |
| """ |
| length = len(msa[0]) |
| i = 0 |
| while i < times: |
| i += 1 |
| item = None |
| for j in range(length): |
| col = random.randint(0, length - 1) |
| if not item: |
| item = msa[:, col : col + 1] |
| else: |
| item += msa[:, col : col + 1] |
| yield item |
|
|
|
|
| def bootstrap_trees(alignment, times, tree_constructor): |
| """Generate bootstrap replicate trees from a multiple sequence alignment. |
| |
| :Parameters: |
| alignment : Alignment or MultipleSeqAlignment object |
| multiple sequence alignment to generate replicates. |
| times : int |
| number of bootstrap times. |
| tree_constructor : TreeConstructor |
| tree constructor to be used to build trees. |
| |
| """ |
| if isinstance(alignment, MultipleSeqAlignment): |
| length = len(alignment[0]) |
| for i in range(times): |
| bootstrapped_alignment = None |
| for j in range(length): |
| col = random.randint(0, length - 1) |
| if bootstrapped_alignment is None: |
| bootstrapped_alignment = alignment[:, col : col + 1] |
| else: |
| bootstrapped_alignment += alignment[:, col : col + 1] |
| tree = tree_constructor.build_tree(bootstrapped_alignment) |
| yield tree |
| else: |
| n, m = alignment.shape |
| for i in range(times): |
| cols = [random.randint(0, m - 1) for j in range(m)] |
| tree = tree_constructor.build_tree(alignment[:, cols]) |
| yield tree |
|
|
|
|
| def bootstrap_consensus(alignment, times, tree_constructor, consensus): |
| """Consensus tree of a series of bootstrap trees for a multiple sequence alignment. |
| |
| :Parameters: |
| alignment : Alignment or MultipleSeqAlignment object |
| Multiple sequence alignment to generate replicates. |
| times : int |
| Number of bootstrap times. |
| tree_constructor : TreeConstructor |
| Tree constructor to be used to build trees. |
| consensus : function |
| Consensus method in this module: ``strict_consensus``, |
| ``majority_consensus``, ``adam_consensus``. |
| |
| """ |
| trees = bootstrap_trees(alignment, times, tree_constructor) |
| tree = consensus(trees) |
| return tree |
|
|
|
|
| def _clade_to_bitstr(clade, tree_term_names): |
| """Create a BitString representing a clade, given ordered tree taxon names (PRIVATE).""" |
| clade_term_names = {term.name for term in clade.find_clades(terminal=True)} |
| return _BitString.from_bool((name in clade_term_names) for name in tree_term_names) |
|
|
|
|
| def _tree_to_bitstrs(tree): |
| """Create a dict of a tree's clades to corresponding BitStrings (PRIVATE).""" |
| clades_bitstrs = {} |
| term_names = [term.name for term in tree.find_clades(terminal=True)] |
| for clade in tree.find_clades(terminal=False): |
| bitstr = _clade_to_bitstr(clade, term_names) |
| clades_bitstrs[clade] = bitstr |
| return clades_bitstrs |
|
|
|
|
| def _bitstring_topology(tree): |
| """Generate a branch length dict for a tree, keyed by BitStrings (PRIVATE). |
| |
| Create a dict of all clades' BitStrings to the corresponding branch |
| lengths (rounded to 5 decimal places). |
| """ |
| bitstrs = {} |
| for clade, bitstr in _tree_to_bitstrs(tree).items(): |
| bitstrs[bitstr] = round(clade.branch_length or 0.0, 5) |
| return bitstrs |
|
|
|
|
| def _equal_topology(tree1, tree2): |
| """Are two trees are equal in terms of topology and branch lengths (PRIVATE). |
| |
| (Branch lengths checked to 5 decimal places.) |
| """ |
| term_names1 = {term.name for term in tree1.find_clades(terminal=True)} |
| term_names2 = {term.name for term in tree2.find_clades(terminal=True)} |
| return (term_names1 == term_names2) and ( |
| _bitstring_topology(tree1) == _bitstring_topology(tree2) |
| ) |
|
|