physarum / tests /test_physarum.py
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add Physarum flow solver (shortest path / network); card leads with it
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import torch
import kernels
physarum = kernels.get_kernel("phanerozoic/physarum", version=1, trust_remote_code=True)
def test_network_develops():
sim = physarum.Physarum(width=256, height=256, agents=20000, seed=1)
sim.step(120)
t = sim.trail
assert torch.isfinite(t).all()
assert float(t.max()) > 0.0
# a network is high-contrast, not a uniform wash
assert float(t.std()) > 0.4 * float(t.mean())
def test_image_shape():
sim = physarum.Physarum(width=128, height=128, agents=5000, seed=2)
sim.step(60)
img = sim.image()
assert tuple(img.shape) == (128, 128, 3)
assert img.dtype == torch.uint8
def test_deterministic():
a = physarum.Physarum(width=128, height=128, agents=5000, seed=7); a.step(40)
b = physarum.Physarum(width=128, height=128, agents=5000, seed=7); b.step(40)
assert torch.equal(a.trail, b.trail)
def _bfs_len(net, a, b):
import collections
H, W = net.shape
seen = torch.zeros(H, W, dtype=torch.bool); seen[a[1], a[0]] = True
q = collections.deque([(a[0], a[1], 0)])
while q:
x, y, d = q.popleft()
if (x, y) == b:
return d
for dx, dy in ((1, 0), (-1, 0), (0, 1), (0, -1)):
nx, ny = x + dx, y + dy
if 0 <= nx < W and 0 <= ny < H and bool(net[ny, nx]) and not seen[ny, nx]:
seen[ny, nx] = True; q.append((nx, ny, d + 1))
return None
def test_flow_solves_maze():
mk = physarum.maze(65, 65, seed=3)
src, goal = (2, 2), (62, 62)
f = physarum.PhysarumFlow(mk).solve([src, goal], [1, -1], iters=150, cg_iters=100)
path = f.path(src, goal)
assert path is not None # terminals connected
assert len(path) - 1 == _bfs_len(mk.bool(), src, goal) # equals the shortest path
def test_flow_network_connects():
open_mask = torch.ones(80, 80); open_mask[0] = 0; open_mask[-1] = 0
open_mask[:, 0] = 0; open_mask[:, -1] = 0
terms = [(40, 40), (12, 12), (68, 12), (12, 68), (68, 68)]
f = physarum.PhysarumFlow(open_mask).solve(terms, [4, -1, -1, -1, -1], iters=200)
assert all(f.path(terms[0], t) is not None for t in terms[1:])