networkx.algorithms.shortest_paths.generic.shortest_path

shortest_path(G, source=None, target=None, weight=None, method='dijkstra')[source]

Compute shortest paths in the graph.

Parameters:
  • G (NetworkX graph)
  • source (node, optional) – Starting node for path. If not specified, compute shortest paths for each possible starting node.
  • target (node, optional) – Ending node for path. If not specified, compute shortest paths to all possible 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.
  • method (string, optional (default = ‘dijkstra’)) – The algorithm to use to compute the path. Supported options: ‘dijkstra’, ‘bellman-ford’. Other inputs produce a ValueError. If weight is None, unweighted graph methods are used, and this suggestion is ignored.
Returns:

path – 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].

Return type:

list or dictionary

Raises:
  • NodeNotFound – If source is not in G.
  • ValueError – If method is not among the supported options.

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]

Notes

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

See also

all_pairs_shortest_path(), all_pairs_dijkstra_path(), all_pairs_bellman_ford_path(), single_source_shortest_path(), single_source_dijkstra_path(), single_source_bellman_ford_path()