bellman_ford_path_length#
- bellman_ford_path_length(G, source, target, weight='weight')[source]#
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
tov
will beG.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 inG
.- NetworkXNoPath
If no path exists between source and target.
See also
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 ----
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, callableweight
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.
graphblas : OpenMP-enabled sparse linear algebra backend.