bellman_ford_path_length

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

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

Parameters

GNetworkX graph

sourcenode label

starting node for path

targetnode label

ending node for path

weightstring or function (default=”weight”)

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

lengthnumber

Shortest path length.

Raises

NodeNotFound

If source is not in G.

NetworkXNoPath

If no path exists between source and target.

See also

dijkstra_path_length, bellman_ford_path

Notes

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

Examples

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