def test_cycle(self):
not_a_dag = retworkx.generators.directed_cycle_graph(250)
with self.assertRaises(retworkx.DAGHasCycle):
retworkx.dag_weighted_longest_path_length(not_a_dag,
lambda *_: 1.0)
with self.assertRaises(retworkx.DAGHasCycle):
retworkx.dag_weighted_longest_path(not_a_dag, lambda *_: 1.0)
def test_nan_not_valid_weight(self):
dag = retworkx.generators.directed_path_graph(526)
def weight_fn(*_):
return float("nan")
with self.assertRaises(ValueError):
retworkx.dag_weighted_longest_path_length(dag, weight_fn)
with self.assertRaises(ValueError):
retworkx.dag_weighted_longest_path(dag, weight_fn)
def test_linear_with_weight(self):
"""Longest depth for a simple dag.
a
|
b
|\
c d
|\
e |
| |
f g
"""
dag = retworkx.PyDAG()
node_a = dag.add_node("a")
node_b = dag.add_child(node_a, "b", 4)
node_c = dag.add_child(node_b, "c", 4)
dag.add_child(node_b, "d", 5)
node_e = dag.add_child(node_c, "e", 2)
dag.add_child(node_e, "f", 2)
node_g = dag.add_child(node_c, "g", 15)
self.assertEqual(
23.0,
retworkx.dag_weighted_longest_path_length(
dag, lambda _, __, weight: float(weight)),
)
self.assertEqual(
[node_a, node_b, node_c, node_g],
retworkx.dag_weighted_longest_path(
dag, lambda _, __, weight: float(weight)),
)
def test_empty_graph_with_weights(self):
dag = retworkx.PyDAG()
self.assertEqual(
0.0,
retworkx.dag_weighted_longest_path_length(
dag, lambda x: float(weight_fn(x))),
)
self.assertEqual(
[],
retworkx.dag_weighted_longest_path(dag,
lambda x: float(weight_fn(x))),
)
def test_degenerate_graph_with_weight(self):
dag = retworkx.PyDAG()
dag.add_node(0)
self.assertEqual(
0.0,
retworkx.dag_weighted_longest_path_length(
dag, lambda x: float(weight_fn(x))),
)
self.assertEqual(
[0],
retworkx.dag_weighted_longest_path(dag,
lambda x: float(weight_fn(x))),
)
def test_less_linear_with_weight(self):
dag = retworkx.PyDAG()
node_a = dag.add_node("a")
node_b = dag.add_child(node_a, "b", 1)
node_c = dag.add_child(node_b, "c", 1)
node_d = dag.add_child(node_c, "d", 1)
node_e = dag.add_child(node_d, "e", 1)
dag.add_edge(node_a, node_c, 3)
dag.add_edge(node_a, node_e, 3)
dag.add_edge(node_c, node_e, 3)
self.assertEqual(
6.0,
retworkx.dag_weighted_longest_path_length(
dag, weight_fn=lambda _, __, weight: float(weight)),
)
self.assertEqual(
[node_a, node_c, node_e],
retworkx.dag_weighted_longest_path(
dag, weight_fn=lambda _, __, weight: float(weight)),
)
def test_parallel_edges_with_weights(self):
dag = retworkx.PyDiGraph()
dag.extend_from_weighted_edge_list([
(0, 1, 1),
(0, 3, 1),
(3, 4, 1),
(4, 5, 1),
(1, 2, 1),
(0, 1, 3),
])
self.assertEqual(
4.0,
retworkx.dag_weighted_longest_path_length(
dag, weight_fn=lambda _, __, weight: float(weight)),
)
self.assertEqual(
[0, 1, 2],
retworkx.dag_weighted_longest_path(
dag, lambda _, __, weight: float(weight)),
)