single_source_bellman_ford_path_length(G, source, weight='weight')[source]#

Compute the shortest path length between source and all other reachable nodes for a weighted graph.

GNetworkX graph
sourcenode label

Starting 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.


Dictionary of shortest path length keyed by target


If source is not in G.


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


>>> G = nx.path_graph(5)
>>> length = nx.single_source_bellman_ford_path_length(G, 0)
>>> length[4]
>>> for node in [0, 1, 2, 3, 4]:
...     print(f"{node}: {length[node]}")
0: 0
1: 1
2: 2
3: 3
4: 4

Additional backends implement this function

graphblas : OpenMP-enabled sparse linear algebra backend.