all_pairs_bellman_ford_shortest_paths(graph, edge_cost_fn)[source]#

For each node in the graph, finds the shortest paths to all others.

This function will generate the shortest path from all nodes in the graph using the Bellman-Ford algorithm. This function is multithreaded and will run launch a thread pool with threads equal to the number of CPUs by default. You can tune the number of threads with the RAYON_NUM_THREADS environment variable. For example, setting RAYON_NUM_THREADS=4 would limit the thread pool to 4 threads.

  • graph – The input graph to use. Can either be a PyGraph or PyDiGraph

  • edge_cost_fn – A callable object that acts as a weight function for an edge. It will accept a single positional argument, the edge’s weight object and will return a float which will be used to represent the weight/cost of the edge


A read-only dictionary of paths. The keys are source node indices and the values are a dict of target node indices and a list of node indices making the path. For example:

    0: {1: [0, 1],  2: [0, 1, 2]},
    1: {2: [1, 2]},
    2: {0: [2, 0]},

Return type:



NegativeCycle: when there is a negative cycle and the shortest path is not defined