python实现最短路径

1. python多个起点不交叉最短路径

1 针对给定的多个起点和终点，如果要求起点之间不交叉，那么存在最短运禅路径。

2 因为起点之间不交叉，可以将问题简化为多个单起点单终点的问题，可以使用 Dijkstra 算法或者 A* 算法等察汪求解最短路径的算法。

3 如果需要考虑多个起点之间的交叉情况，可以考虑使用遗传算法等旁没尘启发式算法，不过这样的算法复杂度较高，需要更长的计算时间。

2. python networkx模块里面计算最短路径时，如何处理等价路径我怎么测试只能显示1条路径，请大神赐教。

if source is None: if target is None: ## Find paths between all pairs. if weight is None: paths=nx.all_pairs_shortest_path(G) else: paths=nx.all_pairs_dijkstra_path(G,weight=weight) else: ## Find paths from all nodes co-accessible to the target. directed = G.is_directed() if directed: G.reverse(=False) if weight is None: paths=nx.single_source_shortest_path(G,target) else: paths=nx.single_source_dijkstra_path(G,target,weight=weight) # Now flip the paths so they go from a source to the target. for target in paths: paths[target] = list(reversed(paths[target])) if directed: G.reverse(=False) else: if target is None: ## Find paths to all nodes accessible from the source. if weight is None: paths=nx.single_source_shortest_path(G,source) else: paths=nx.single_source_dijkstra_path(G,source,weight=weight) else: ## Find shortest source-target path. if weight is None: paths=nx.bidirectional_shortest_path(G,source,target) else: paths=nx.dijkstra_path(G,source,target,weight)

3. Python中networkx中shortest_path使用的是哪一种最短路径方法

不全是。依据传入的参数决定调用哪种算法。

看源码：至少涉及了dijkstra、广乎灶度优先/深度优先算法。

ifsource岁迟扮isNone:
iftargetisNone:
##Findpathsbetweenallpairs.
ifweightisNone:
paths=nx.all_pairs_shortest_path(G)
else:
paths=nx.all_pairs_dijkstra_path(G,weight=weight)
else:
##Findpathsfromallnodesco-accessibletothetarget.
旦桐directed=G.is_directed()
ifdirected:
G.reverse(=False)

ifweightisNone:
paths=nx.single_source_shortest_path(G,target)
else:
paths=nx.single_source_dijkstra_path(G,target,weight=weight)

#.
fortargetinpaths:
paths[target]=list(reversed(paths[target]))

ifdirected:
G.reverse(=False)
else:
iftargetisNone:
##.
ifweightisNone:
paths=nx.single_source_shortest_path(G,source)
else:
paths=nx.single_source_dijkstra_path(G,source,weight=weight)
else:
##Findshortestsource-targetpath.
ifweightisNone:
paths=nx.bidirectional_shortest_path(G,source,target)
else:
paths=nx.dijkstra_path(G,source,target,weight)