def test_already_arborescence(self):
"""Tests that a directed acyclic graph that is already an
arborescence produces an isomorphic arborescence as output.
"""
A = nx.balanced_tree(2, 2, create_using=nx.DiGraph())
B = nx.dag_to_branching(A)
assert_true(nx.is_isomorphic(A, B))
def circuit_to_formula(circuit):
# Convert the circuit to an equivalent formula.
formula = dag_to_branching(circuit)
# Transfer the operator or variable labels for each node from the
# circuit to the formula.
for v in formula:
source = formula.node[v]['source']
formula.node[v]['label'] = circuit.node[source]['label']
return formula
def test_already_branching(self):
"""Tests that a directed acyclic graph that is already a
branching produces an isomorphic branching as output.
"""
T1 = nx.balanced_tree(2, 2, create_using=nx.DiGraph())
T2 = nx.balanced_tree(2, 2, create_using=nx.DiGraph())
G = nx.disjoint_union(T1, T2)
B = nx.dag_to_branching(G)
assert_true(nx.is_isomorphic(G, B))
def test_single_root(self):
"""Tests that a directed acyclic graph with a single degree
zero node produces an arborescence.
"""
G = nx.DiGraph([(0, 1), (0, 2), (1, 3), (2, 3)])
B = nx.dag_to_branching(G)
expected = nx.DiGraph([(0, 1), (1, 3), (0, 2), (2, 4)])
assert_true(nx.is_arborescence(B))
assert_true(nx.is_isomorphic(B, expected))
def test_multiple_roots(self):
"""Tests that a directed acyclic graph with multiple degree zero
nodes creates an arborescence with multiple (weakly) connected
components.
"""
G = nx.DiGraph([(0, 1), (0, 2), (1, 3), (2, 3), (5, 2)])
B = nx.dag_to_branching(G)
expected = nx.DiGraph([(0, 1), (1, 3), (0, 2), (2, 4), (5, 6), (6, 7)])
assert_true(nx.is_branching(B))
assert_false(nx.is_arborescence(B))
assert_true(nx.is_isomorphic(B, expected))
def test_multidigraph(self):
nx.dag_to_branching(nx.MultiDiGraph())
def test_undirected(self):
nx.dag_to_branching(nx.Graph())
def test_not_acyclic(self):
"""Tests that a non-acyclic graph causes an exception."""
G = nx.DiGraph(pairwise('abc', cyclic=True))
nx.dag_to_branching(G)
def test_multigraph(self):
with pytest.raises(nx.NetworkXNotImplemented):
nx.dag_to_branching(nx.MultiGraph())
def test_undirected(self):
with pytest.raises(nx.NetworkXNotImplemented):
nx.dag_to_branching(nx.Graph())
def test_not_acyclic(self):
"""Tests that a non-acyclic graph causes an exception."""
with pytest.raises(nx.HasACycle):
G = nx.DiGraph(pairwise("abc", cyclic=True))
nx.dag_to_branching(G)
def test_multidigraph(self):
nx.dag_to_branching(nx.MultiDiGraph())
def test_undirected(self):
nx.dag_to_branching(nx.Graph())
def test_not_acyclic(self):
"""Tests that a non-acyclic graph causes an exception."""
G = nx.DiGraph(pairwise('abc', cyclic=True))
nx.dag_to_branching(G)