def test_should_return_shortest_distances_and_predecessors_for_graph_with_connected_components(
self):
dg = nx.DiGraph()
dg.add_weighted_edges_from([(1, 3, 1), (3, 5, 1), (5, 7, 1)])
dg.add_weighted_edges_from([(0, 2, 2), (2, 4, 2), (4, 6, 2)])
distances, predecessors = dijkstra(graph=graph.Graph(dg),
source_node=1,
distance_struct=self.struct)
assert_that(distances, has_length(8))
assert_that(
distances,
has_entries({
0: math.inf,
1: 0,
2: math.inf,
3: 1,
4: math.inf,
5: 2,
6: math.inf,
7: 3
}))
assert_that(predecessors, has_length(3))
assert_that(predecessors, has_entries({3: 1, 5: 3, 7: 5}))
def test_should_return_shortest_distances_and_predecessors_for_equally_weighted_graph_with_many_paths(
self):
dg = nx.DiGraph()
dg.add_weighted_edges_from([(0, 1, 1), (0, 2, 1), (1, 3, 1),
(2, 3, 1)])
distances, predecessors = dijkstra(graph=graph.Graph(dg),
source_node=0,
distance_struct=self.struct)
assert_that(distances, has_length(4))
assert_that(distances, has_entries({0: 0, 1: 1, 2: 1, 3: 2}))
assert_that(predecessors, has_length(3))
assert_that(
predecessors,
any_of(has_entries({
1: 0,
2: 0,
3: 2
}), has_entries({
1: 0,
2: 0,
3: 1
})))
def test_should_return_shortest_distances_and_predecessors_for_graph_with_unreachble_nodes(
self):
dg = nx.DiGraph()
dg.add_node(0)
dg.add_node(1)
dg.add_node(2)
distances, predecessors = dijkstra(graph=graph.Graph(dg),
source_node=0,
distance_struct=self.struct)
assert_that(distances, has_length(3))
assert_that(distances, has_entries({0: 0, 1: math.inf, 2: math.inf}))
assert_that(predecessors, empty())
def test_should_return_shortest_distances_and_predecessors_for_differently_weighted_graph_with_many_paths(
self):
dg = nx.DiGraph()
dg.add_weighted_edges_from([(0, 1, 4), (1, 3, 1), (3, 5, 1)])
dg.add_weighted_edges_from([(0, 2, 1), (2, 4, 1), (4, 5, 1)])
distances, predecessors = dijkstra(graph=graph.Graph(dg),
source_node=0,
distance_struct=self.struct)
assert_that(distances, has_length(6))
assert_that(distances, has_entries({
0: 0,
1: 4,
2: 1,
3: 5,
4: 2,
5: 3
}))
assert_that(predecessors, has_length(5))
assert_that(predecessors, has_entries({1: 0, 2: 0, 3: 1, 4: 2, 5: 4}))