def test_bfs_subgraph_does_not_reverse_egde_direction(self):
graph = Graph()
graph.add_node('A')
graph.add_node('B')
graph.add_node('C')
graph.add_edge('A', 'B')
graph.add_edge('B', 'C')
whole_graph = graph.forw_topo_sort()
subgraph_backward = graph.back_bfs_subgraph('C')
subgraph_backward = subgraph_backward.forw_topo_sort()
self.assertEquals(whole_graph, subgraph_backward)
subgraph_forward = graph.forw_bfs_subgraph('A')
subgraph_forward = subgraph_forward.forw_topo_sort()
self.assertEquals(whole_graph, subgraph_forward)
def test_toposort(self):
graph = Graph()
graph.add_node(1)
graph.add_node(2)
graph.add_node(3)
graph.add_node(4)
graph.add_node(5)
graph.add_edge(1, 2)
graph.add_edge(1, 3)
graph.add_edge(2, 4)
graph.add_edge(3, 5)
ok, result = graph.forw_topo_sort()
self.assertTrue(ok)
for idx in range(1, 6):
self.assertTrue(idx in result)
self.assertTrue(result.index(1) < result.index(2))
self.assertTrue(result.index(1) < result.index(3))
self.assertTrue(result.index(2) < result.index(4))
self.assertTrue(result.index(3) < result.index(5))
ok, result = graph.back_topo_sort()
self.assertTrue(ok)
for idx in range(1, 6):
self.assertTrue(idx in result)
self.assertTrue(result.index(2) < result.index(1))
self.assertTrue(result.index(3) < result.index(1))
self.assertTrue(result.index(4) < result.index(2))
self.assertTrue(result.index(5) < result.index(3))
# Same graph as before, but with edges
# reversed, which means we should get
# the same results as before if using
# back_topo_sort rather than forw_topo_sort
# (and v.v.)
graph = Graph()
graph.add_node(1)
graph.add_node(2)
graph.add_node(3)
graph.add_node(4)
graph.add_node(5)
graph.add_edge(2, 1)
graph.add_edge(3, 1)
graph.add_edge(4, 2)
graph.add_edge(5, 3)
ok, result = graph.back_topo_sort()
self.assertTrue(ok)
for idx in range(1, 6):
self.assertTrue(idx in result)
self.assertTrue(result.index(1) < result.index(2))
self.assertTrue(result.index(1) < result.index(3))
self.assertTrue(result.index(2) < result.index(4))
self.assertTrue(result.index(3) < result.index(5))
ok, result = graph.forw_topo_sort()
self.assertTrue(ok)
for idx in range(1, 6):
self.assertTrue(idx in result)
self.assertTrue(result.index(2) < result.index(1))
self.assertTrue(result.index(3) < result.index(1))
self.assertTrue(result.index(4) < result.index(2))
self.assertTrue(result.index(5) < result.index(3))
# Create a cycle
graph.add_edge(1, 5)
ok, result = graph.forw_topo_sort()
self.assertFalse(ok)
ok, result = graph.back_topo_sort()
self.assertFalse(ok)
