def positive_single_tree(t1):
assert nx.is_tree(t1)
nodes1 = [n for n in t1.nodes()]
# get a random permutation of this
nodes2 = nodes1.copy()
random.shuffle(nodes2)
# this is one isomorphism, however they may be multiple
# so we don't necessarily get this one back
someisomorphism = [(u, v) for (u, v) in zip(nodes1, nodes2)]
# map from old to new
map1to2 = {u: v for (u, v) in someisomorphism}
# get the edges with the transformed names
edges2 = [random_swap((map1to2[u], map1to2[v])) for (u, v) in t1.edges()]
# randomly permute, to ensure we're not relying on edge order somehow
random.shuffle(edges2)
# so t2 is isomorphic to t1
t2 = nx.Graph()
t2.add_edges_from(edges2)
# lets call our code to see if t1 and t2 are isomorphic
isomorphism = tree_isomorphism(t1, t2)
# make sure we got a correct solution
# although not necessarily someisomorphism
assert len(isomorphism) > 0
assert check_isomorphism(t1, t2, isomorphism)
def test_negative(maxk=11):
print("negative test")
for k in range(4, maxk + 1):
test_trees = list(nx.nonisomorphic_trees(k))
start_time = time.time()
trial = 0
for i in range(len(test_trees) - 1):
for j in range(i + 1, len(test_trees)):
trial += 1
assert tree_isomorphism(test_trees[i], test_trees[j]) == []
print(k, trial, time.time() - start_time)
def test_trivial_2():
print("trivial test 2")
edges_1 = [("a", "b"), ("a", "c")]
edges_2 = [("v", "y")]
t1 = nx.Graph()
t1.add_edges_from(edges_1)
t2 = nx.Graph()
t2.add_edges_from(edges_2)
isomorphism = tree_isomorphism(t1, t2)
# they cannot be isomorphic,
# since they have different numbers of nodes
assert isomorphism == []