shortest_path

shortest_path(G, source=None, target=None, weight=None)

Compute shortest paths in the graph.

Parameters :

G : NetworkX graph

source : node, optional

Starting node for path. If not specified, compute shortest paths using all nodes as source nodes.

target : node, optional

Ending node for path. If not specified, compute shortest paths using all nodes as target nodes.

weight : None or string, optional (default = None)

If None, every edge has weight/distance/cost 1. If a string, use this edge attribute as the edge weight. Any edge attribute not present defaults to 1.

Returns :

path: list or dictionary :

All returned paths include both the source and target in the path.

If the source and target are both specified, return a single list of nodes in a shortest path from the source to the target.

If only the source is specified, return a dictionary keyed by targets with a list of nodes in a shortest path from the source to one of the targets.

If only the target is specified, return a dictionary keyed by sources with a list of nodes in a shortest path from one of the sources to the target.

If neither the source nor target are specified return a dictionary of dictionaries with path[source][target]=[list of nodes in path].

See also

all_pairs_shortest_path, all_pairs_dijkstra_path, single_source_shortest_path, single_source_dijkstra_path

Notes

There may be more than one shortest path between a source and target. This returns only one of them.

For digraphs this returns a shortest directed path. To find paths in the reverse direction first use G.reverse(copy=False) to flip the edge orientation.

Examples

>>> G=nx.path_graph(5)
>>> print(nx.shortest_path(G,source=0,target=4))
[0, 1, 2, 3, 4]
>>> p=nx.shortest_path(G,source=0) # target not specified
>>> p[4]
[0, 1, 2, 3, 4]
>>> p=nx.shortest_path(G,target=4) # source not specified
>>> p[0]
[0, 1, 2, 3, 4]
>>> p=nx.shortest_path(G) # source,target not specified
>>> p[0][4]
[0, 1, 2, 3, 4]