Warning

This documents an unmaintained version of NetworkX. Please upgrade to a maintained version and see the current NetworkX documentation.

networkx.algorithms.shortest_paths.weighted.dijkstra_path_length

dijkstra_path_length(G, source, target, weight='weight')

Returns the shortest weighted path length in G from source to target.

Uses Dijkstra’s Method to compute the shortest weighted path length between two nodes in a graph.

Parameters

• G (NetworkX graph)

• source (node label) – starting node for path

• target (node label) – ending node for path

• weight (string or function) – If this is a string, then edge weights will be accessed via the edge attribute with this key (that is, the weight of the edge joining u to v will be G.edges[u, v][weight]). If no such edge attribute exists, the weight of the edge is assumed to be one.

  If this is a function, the weight of an edge is the value returned by the function. The function must accept exactly three positional arguments: the two endpoints of an edge and the dictionary of edge attributes for that edge. The function must return a number.

Returns

length – Shortest path length.

Return type

number

Raises

• NodeNotFound – If source is not in G.

• NetworkXNoPath – If no path exists between source and target.

Examples

>>> G=nx.path_graph(5)
>>> print(nx.dijkstra_path_length(G,0,4))
4

Notes

Edge weight attributes must be numerical. Distances are calculated as sums of weighted edges traversed.

The weight function can be used to hide edges by returning None. So weight = lambda u, v, d: 1 if d['color']=="red" else None will find the shortest red path.

The function single_source_dijkstra() computes both path and length-of-path if you need both, use that.

See also

bidirectional_dijkstra(), bellman_ford_path_length(), single_source_dijkstra()