191 lines
6.4 KiB
Python
191 lines
6.4 KiB
Python
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from unittest import TestCase
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import collections
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import pytest
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import networkx as nx
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class TestIsEulerian(TestCase):
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def test_is_eulerian(self):
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assert nx.is_eulerian(nx.complete_graph(5))
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assert nx.is_eulerian(nx.complete_graph(7))
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assert nx.is_eulerian(nx.hypercube_graph(4))
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assert nx.is_eulerian(nx.hypercube_graph(6))
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assert not nx.is_eulerian(nx.complete_graph(4))
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assert not nx.is_eulerian(nx.complete_graph(6))
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assert not nx.is_eulerian(nx.hypercube_graph(3))
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assert not nx.is_eulerian(nx.hypercube_graph(5))
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assert not nx.is_eulerian(nx.petersen_graph())
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assert not nx.is_eulerian(nx.path_graph(4))
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def test_is_eulerian2(self):
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# not connected
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G = nx.Graph()
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G.add_nodes_from([1, 2, 3])
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assert not nx.is_eulerian(G)
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# not strongly connected
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G = nx.DiGraph()
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G.add_nodes_from([1, 2, 3])
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assert not nx.is_eulerian(G)
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G = nx.MultiDiGraph()
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G.add_edge(1, 2)
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G.add_edge(2, 3)
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G.add_edge(2, 3)
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G.add_edge(3, 1)
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assert not nx.is_eulerian(G)
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class TestEulerianCircuit(TestCase):
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def test_eulerian_circuit_cycle(self):
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G = nx.cycle_graph(4)
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edges = list(nx.eulerian_circuit(G, source=0))
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nodes = [u for u, v in edges]
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assert nodes == [0, 3, 2, 1]
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assert edges == [(0, 3), (3, 2), (2, 1), (1, 0)]
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edges = list(nx.eulerian_circuit(G, source=1))
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nodes = [u for u, v in edges]
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assert nodes == [1, 2, 3, 0]
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assert edges == [(1, 2), (2, 3), (3, 0), (0, 1)]
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G = nx.complete_graph(3)
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edges = list(nx.eulerian_circuit(G, source=0))
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nodes = [u for u, v in edges]
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assert nodes == [0, 2, 1]
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assert edges == [(0, 2), (2, 1), (1, 0)]
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edges = list(nx.eulerian_circuit(G, source=1))
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nodes = [u for u, v in edges]
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assert nodes == [1, 2, 0]
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assert edges == [(1, 2), (2, 0), (0, 1)]
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def test_eulerian_circuit_digraph(self):
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G = nx.DiGraph()
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nx.add_cycle(G, [0, 1, 2, 3])
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edges = list(nx.eulerian_circuit(G, source=0))
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nodes = [u for u, v in edges]
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assert nodes == [0, 1, 2, 3]
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assert edges == [(0, 1), (1, 2), (2, 3), (3, 0)]
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edges = list(nx.eulerian_circuit(G, source=1))
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nodes = [u for u, v in edges]
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assert nodes == [1, 2, 3, 0]
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assert edges == [(1, 2), (2, 3), (3, 0), (0, 1)]
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def test_multigraph(self):
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G = nx.MultiGraph()
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nx.add_cycle(G, [0, 1, 2, 3])
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G.add_edge(1, 2)
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G.add_edge(1, 2)
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edges = list(nx.eulerian_circuit(G, source=0))
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nodes = [u for u, v in edges]
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assert nodes == [0, 3, 2, 1, 2, 1]
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assert edges == [(0, 3), (3, 2), (2, 1), (1, 2), (2, 1), (1, 0)]
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def test_multigraph_with_keys(self):
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G = nx.MultiGraph()
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nx.add_cycle(G, [0, 1, 2, 3])
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G.add_edge(1, 2)
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G.add_edge(1, 2)
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edges = list(nx.eulerian_circuit(G, source=0, keys=True))
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nodes = [u for u, v, k in edges]
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assert nodes == [0, 3, 2, 1, 2, 1]
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assert edges[:2] == [(0, 3, 0), (3, 2, 0)]
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assert collections.Counter(edges[2:5]) == collections.Counter([(2, 1, 0), (1, 2, 1), (2, 1, 2)])
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assert edges[5:] == [(1, 0, 0)]
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def test_not_eulerian(self):
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with pytest.raises(nx.NetworkXError):
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f = list(nx.eulerian_circuit(nx.complete_graph(4)))
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class TestIsSemiEulerian(TestCase):
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def test_is_semieulerian(self):
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# Test graphs with Eulerian paths but no cycles return True.
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assert nx.is_semieulerian(nx.path_graph(4))
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G = nx.path_graph(6, create_using=nx.DiGraph)
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assert nx.is_semieulerian(G)
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# Test graphs with Eulerian cycles return False.
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assert not nx.is_semieulerian(nx.complete_graph(5))
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assert not nx.is_semieulerian(nx.complete_graph(7))
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assert not nx.is_semieulerian(nx.hypercube_graph(4))
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assert not nx.is_semieulerian(nx.hypercube_graph(6))
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class TestHasEulerianPath(TestCase):
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def test_has_eulerian_path_cyclic(self):
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# Test graphs with Eulerian cycles return True.
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assert nx.has_eulerian_path(nx.complete_graph(5))
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assert nx.has_eulerian_path(nx.complete_graph(7))
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assert nx.has_eulerian_path(nx.hypercube_graph(4))
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assert nx.has_eulerian_path(nx.hypercube_graph(6))
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def test_has_eulerian_path_non_cyclic(self):
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# Test graphs with Eulerian paths but no cycles return True.
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assert nx.has_eulerian_path(nx.path_graph(4))
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G = nx.path_graph(6, create_using=nx.DiGraph)
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assert nx.has_eulerian_path(G)
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class TestFindPathStart(TestCase):
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def testfind_path_start(self):
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find_path_start = nx.algorithms.euler._find_path_start
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# Test digraphs return correct starting node.
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G = nx.path_graph(6, create_using=nx.DiGraph)
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assert find_path_start(G) == 0
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edges = [(0, 1), (1, 2), (2, 0), (4, 0)]
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assert find_path_start(nx.DiGraph(edges)) == 4
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# Test graph with no Eulerian path return None.
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edges = [(0, 1), (1, 2), (2, 3), (2, 4)]
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assert find_path_start(nx.DiGraph(edges)) == None
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class TestEulerianPath(TestCase):
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def test_eulerian_path(self):
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x = [(4, 0), (0, 1), (1, 2), (2, 0)]
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for e1, e2 in zip(x, nx.eulerian_path(nx.DiGraph(x))):
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assert e1 == e2
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class TestEulerize(TestCase):
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def test_disconnected(self):
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with pytest.raises(nx.NetworkXError):
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G = nx.from_edgelist([(0, 1), (2, 3)])
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nx.eulerize(G)
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def test_null_graph(self):
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with pytest.raises(nx.NetworkXPointlessConcept):
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nx.eulerize(nx.Graph())
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def test_null_multigraph(self):
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with pytest.raises(nx.NetworkXPointlessConcept):
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nx.eulerize(nx.MultiGraph())
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def test_on_empty_graph(self):
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with pytest.raises(nx.NetworkXError):
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nx.eulerize(nx.empty_graph(3))
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def test_on_eulerian(self):
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G = nx.cycle_graph(3)
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H = nx.eulerize(G)
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assert nx.is_isomorphic(G, H)
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def test_on_eulerian_multigraph(self):
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G = nx.MultiGraph(nx.cycle_graph(3))
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G.add_edge(0, 1)
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H = nx.eulerize(G)
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assert nx.is_eulerian(H)
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def test_on_complete_graph(self):
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G = nx.complete_graph(4)
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assert nx.is_eulerian(nx.eulerize(G))
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assert nx.is_eulerian(nx.eulerize(nx.MultiGraph(G)))
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