all_pairs_bellman_ford_path

all_pairs_bellman_ford_path(G, weight='weight')

Compute shortest paths between all nodes in a weighted graph.

Parameters:

GNetworkX graph

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:

pathsiterator

(source, dictionary) iterator with dictionary keyed by target and shortest path as the key value.

See also

floyd_warshall, all_pairs_dijkstra_path

Notes

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

Examples

>>> G = nx.path_graph(5)
>>> path = dict(nx.all_pairs_bellman_ford_path(G))
>>> path[0][4]
[0, 1, 2, 3, 4]
----

Additional backends implement this function

cugraphGPU-accelerated backend.

Negative cycles are not yet supported. NotImplementedError will be raised if there are negative edge weights. We plan to support negative edge weights soon. Also, callable weight argument is not supported.

Additional parameters:

dtypedtype or None, optional

The data type (np.float32, np.float64, or None) to use for the edge weights in the algorithm. If None, then dtype is determined by the edge values.

parallelA networkx backend that uses joblib to run graph algorithms in parallel. Find the nx-parallel’s configuration guide here

The parallel implementation first divides the nodes into chunks and then creates a generator to lazily compute shortest paths for each node_chunk, and then employs joblib’s Parallel function to execute these computations in parallel across n_jobs number of CPU cores.

Additional parameters:

get_chunksstr, function (default = “chunks”)

A function that takes in an iterable of all the nodes as input and returns an iterable node_chunks. The default chunking is done by slicing the G.nodes into n_jobs number of chunks.

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