rustworkx.digraph_bellman_ford_shortest_path_lengths#

digraph_bellman_ford_shortest_path_lengths(graph, node, edge_cost_fn, /, goal=None)#

Compute the lengths of the shortest paths for a PyDiGraph object using the Bellman-Ford algorithm with the SPFA heuristic.

Parameters:

  • graph (PyDiGraph) – The input graph to use

  • node (int) – The node index to use as the source for finding the shortest paths from

  • edge_cost_fn – A python callable that will take in 1 parameter, an edge’s data object and will return a float that represents the cost/weight of that edge. It can be negative.

  • goal (int) – An optional node index to use as the end of the path. When specified the output dictionary will only have a single entry with the length of the shortest path to the goal node.

Returns:

A read-only dictionary of the shortest paths from the provided node where the key is the node index of the end of the path and the value is the cost/sum of the weights of path

Return type:

PathLengthMapping

Raises:

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