158 lines
6.4 KiB
Python
158 lines
6.4 KiB
Python
|
#!/usr/bin/env python
|
||
|
import pytest
|
||
|
import networkx as nx
|
||
|
|
||
|
|
||
|
class TestFloyd:
|
||
|
@classmethod
|
||
|
def setup_class(cls):
|
||
|
pass
|
||
|
|
||
|
def test_floyd_warshall_predecessor_and_distance(self):
|
||
|
XG = nx.DiGraph()
|
||
|
XG.add_weighted_edges_from([('s', 'u', 10), ('s', 'x', 5),
|
||
|
('u', 'v', 1), ('u', 'x', 2),
|
||
|
('v', 'y', 1), ('x', 'u', 3),
|
||
|
('x', 'v', 5), ('x', 'y', 2),
|
||
|
('y', 's', 7), ('y', 'v', 6)])
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(XG)
|
||
|
assert dist['s']['v'] == 9
|
||
|
assert path['s']['v'] == 'u'
|
||
|
assert (dist ==
|
||
|
{'y': {'y': 0, 'x': 12, 's': 7, 'u': 15, 'v': 6},
|
||
|
'x': {'y': 2, 'x': 0, 's': 9, 'u': 3, 'v': 4},
|
||
|
's': {'y': 7, 'x': 5, 's': 0, 'u': 8, 'v': 9},
|
||
|
'u': {'y': 2, 'x': 2, 's': 9, 'u': 0, 'v': 1},
|
||
|
'v': {'y': 1, 'x': 13, 's': 8, 'u': 16, 'v': 0}})
|
||
|
|
||
|
GG = XG.to_undirected()
|
||
|
# make sure we get lower weight
|
||
|
# to_undirected might choose either edge with weight 2 or weight 3
|
||
|
GG['u']['x']['weight'] = 2
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(GG)
|
||
|
assert dist['s']['v'] == 8
|
||
|
# skip this test, could be alternate path s-u-v
|
||
|
# assert_equal(path['s']['v'],'y')
|
||
|
|
||
|
G = nx.DiGraph() # no weights
|
||
|
G.add_edges_from([('s', 'u'), ('s', 'x'),
|
||
|
('u', 'v'), ('u', 'x'),
|
||
|
('v', 'y'), ('x', 'u'),
|
||
|
('x', 'v'), ('x', 'y'),
|
||
|
('y', 's'), ('y', 'v')])
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(G)
|
||
|
assert dist['s']['v'] == 2
|
||
|
# skip this test, could be alternate path s-u-v
|
||
|
# assert_equal(path['s']['v'],'x')
|
||
|
|
||
|
# alternate interface
|
||
|
dist = nx.floyd_warshall(G)
|
||
|
assert dist['s']['v'] == 2
|
||
|
|
||
|
# floyd_warshall_predecessor_and_distance returns
|
||
|
# dicts-of-defautdicts
|
||
|
# make sure we don't get empty dictionary
|
||
|
XG = nx.DiGraph()
|
||
|
XG.add_weighted_edges_from([('v', 'x', 5.0), ('y', 'x', 5.0),
|
||
|
('v', 'y', 6.0), ('x', 'u', 2.0)])
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(XG)
|
||
|
inf = float("inf")
|
||
|
assert (dist ==
|
||
|
{'v': {'v': 0, 'x': 5.0, 'y': 6.0, 'u': 7.0},
|
||
|
'x': {'x': 0, 'u': 2.0, 'v': inf, 'y': inf},
|
||
|
'y': {'y': 0, 'x': 5.0, 'v': inf, 'u': 7.0},
|
||
|
'u': {'u': 0, 'v': inf, 'x': inf, 'y': inf}})
|
||
|
assert (path ==
|
||
|
{'v': {'x': 'v', 'y': 'v', 'u': 'x'},
|
||
|
'x': {'u': 'x'},
|
||
|
'y': {'x': 'y', 'u': 'x'}})
|
||
|
|
||
|
def test_reconstruct_path(self):
|
||
|
with pytest.raises(KeyError):
|
||
|
XG = nx.DiGraph()
|
||
|
XG.add_weighted_edges_from([('s', 'u', 10), ('s', 'x', 5),
|
||
|
('u', 'v', 1), ('u', 'x', 2),
|
||
|
('v', 'y', 1), ('x', 'u', 3),
|
||
|
('x', 'v', 5), ('x', 'y', 2),
|
||
|
('y', 's', 7), ('y', 'v', 6)])
|
||
|
predecessors, _ = nx.floyd_warshall_predecessor_and_distance(XG)
|
||
|
|
||
|
path = nx.reconstruct_path('s', 'v', predecessors)
|
||
|
assert path == ['s', 'x', 'u', 'v']
|
||
|
|
||
|
path = nx.reconstruct_path('s', 's', predecessors)
|
||
|
assert path == []
|
||
|
|
||
|
# this part raises the keyError
|
||
|
nx.reconstruct_path('1', '2', predecessors)
|
||
|
|
||
|
def test_cycle(self):
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(
|
||
|
nx.cycle_graph(7))
|
||
|
assert dist[0][3] == 3
|
||
|
assert path[0][3] == 2
|
||
|
assert dist[0][4] == 3
|
||
|
|
||
|
def test_weighted(self):
|
||
|
XG3 = nx.Graph()
|
||
|
XG3.add_weighted_edges_from([[0, 1, 2], [1, 2, 12], [2, 3, 1],
|
||
|
[3, 4, 5], [4, 5, 1], [5, 0, 10]])
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(XG3)
|
||
|
assert dist[0][3] == 15
|
||
|
assert path[0][3] == 2
|
||
|
|
||
|
def test_weighted2(self):
|
||
|
XG4 = nx.Graph()
|
||
|
XG4.add_weighted_edges_from([[0, 1, 2], [1, 2, 2], [2, 3, 1],
|
||
|
[3, 4, 1], [4, 5, 1], [5, 6, 1],
|
||
|
[6, 7, 1], [7, 0, 1]])
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(XG4)
|
||
|
assert dist[0][2] == 4
|
||
|
assert path[0][2] == 1
|
||
|
|
||
|
def test_weight_parameter(self):
|
||
|
XG4 = nx.Graph()
|
||
|
XG4.add_edges_from([(0, 1, {'heavy': 2}), (1, 2, {'heavy': 2}),
|
||
|
(2, 3, {'heavy': 1}), (3, 4, {'heavy': 1}),
|
||
|
(4, 5, {'heavy': 1}), (5, 6, {'heavy': 1}),
|
||
|
(6, 7, {'heavy': 1}), (7, 0, {'heavy': 1})])
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(XG4,
|
||
|
weight='heavy')
|
||
|
assert dist[0][2] == 4
|
||
|
assert path[0][2] == 1
|
||
|
|
||
|
def test_zero_distance(self):
|
||
|
XG = nx.DiGraph()
|
||
|
XG.add_weighted_edges_from([('s', 'u', 10), ('s', 'x', 5),
|
||
|
('u', 'v', 1), ('u', 'x', 2),
|
||
|
('v', 'y', 1), ('x', 'u', 3),
|
||
|
('x', 'v', 5), ('x', 'y', 2),
|
||
|
('y', 's', 7), ('y', 'v', 6)])
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(XG)
|
||
|
|
||
|
for u in XG:
|
||
|
assert dist[u][u] == 0
|
||
|
|
||
|
GG = XG.to_undirected()
|
||
|
# make sure we get lower weight
|
||
|
# to_undirected might choose either edge with weight 2 or weight 3
|
||
|
GG['u']['x']['weight'] = 2
|
||
|
path, dist = nx.floyd_warshall_predecessor_and_distance(GG)
|
||
|
|
||
|
for u in GG:
|
||
|
dist[u][u] = 0
|
||
|
|
||
|
def test_zero_weight(self):
|
||
|
G = nx.DiGraph()
|
||
|
edges = [(1, 2, -2), (2, 3, -4), (1, 5, 1),
|
||
|
(5, 4, 0), (4, 3, -5), (2, 5, -7)]
|
||
|
G.add_weighted_edges_from(edges)
|
||
|
dist = nx.floyd_warshall(G)
|
||
|
assert dist[1][3] == -14
|
||
|
|
||
|
G = nx.MultiDiGraph()
|
||
|
edges.append((2, 5, -7))
|
||
|
G.add_weighted_edges_from(edges)
|
||
|
dist = nx.floyd_warshall(G)
|
||
|
assert dist[1][3] == -14
|