如果我有一个非常简单的有向多重图
G = nx.MultiDiGraph()
G.add_edge('A', 'B', key=1)
G.add_edge('B', 'C', key=2)
G.add_edge('B', 'C', key=3)
--
(A) -1- (B) -2- (C)
\3/
我希望nx.all_shortest_paths(G, source='A', target='C')
返回
两条路径;
A-1-B-2-C
A-1-B-3-C
但是all_shortest_paths
(因为它目前正在实现)仅返回节点,而不返回节点和边,因此我们只能得到一条路径;
>>> list(nx.all_shortest_paths(G, source='A', target='C'))
[['A', 'B', 'C']]
是否有任何简单/通用的方法来返回实际路径,而不是简单的节点列表?
答案 0 :(得分:1)
networkx
没有内置函数来处理它,因此您必须手动执行所有操作。
nx.all_simple_paths()
返回节点列表,因此对于MultiDiGraph,将有很多重复。因此,我们首先通过将nx.all_simple_paths()
输出转换为set
来删除它们,然后对其进行迭代。对于每条路径,我们提取节点对(例如:[1,2,3,4] -> [[1,2],[2,3],[3,4]]
),对于每对路径,我们得到节点之间所有边的AtlasView
。这是该算法的代码:
import networkx as nx
from pprint import pprint
# Create the graph with unique edges to check the algorithm correctness
G = nx.MultiDiGraph()
G.add_edges_from([
[1,2],
[1,2],
[1,2],
[2,3],
[2,3],
[2,3],
[3,4],
[3,4],
[2,4]
])
G.add_edge(1,2,data='WAKA')
G.add_edge(2,3,data='WAKKA')
G.add_edge(2,4,data='WAKA-WAKA')
# Our source and destination nodes
source = 1
destination = 4
# All unique single paths, like in nx.DiGraph
unique_single_paths = set(
tuple(path) # Sets can't be used with lists because they are not hashable
for path in nx.all_simple_paths(G, source, destination)
)
combined_single_paths = []
for path in unique_single_paths:
# Get all node pairs in path:
# [1,2,3,4] -> [[1,2],[2,3],[3,4]]
pairs = [path[i: i + 2] for i in range(len(path)-1)]
# Construct the combined list for path
combined_single_paths.append([
(pair, G[pair[0]][pair[1]]) # Pair and all node between these nodes
for pair in pairs
])
pprint(combined_single_paths)
[[((1, 2), AtlasView({0: {}, 1: {}, 2: {}, 3: {'data': 'WAKA'}})),
((2, 3), AtlasView({0: {}, 1: {}, 2: {}, 3: {'data': 'WAKKA'}})),
((3, 4), AtlasView({0: {}, 1: {}}))],
[((1, 2), AtlasView({0: {}, 1: {}, 2: {}, 3: {'data': 'WAKA'}})),
((2, 4), AtlasView({0: {}, 1: {'data': 'WAKA-WAKA'}}))]]