networkx.algorithms.shortest_paths.weighted.single_source_dijkstra_path_length¶
- single_source_dijkstra_path_length(G, source, cutoff=None, weight='weight')[source]¶
Find shortest weighted path lengths in G from a source node.
Compute the shortest path length between source and all other reachable nodes for a weighted graph.
- Parameters
- GNetworkX graph
- sourcenode label
Starting node for path
- cutoffinteger or float, optional
Length (sum of edge weights) at which the search is stopped. If cutoff is provided, only return paths with summed weight <= cutoff.
- weightstring or function
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
- lengthdict
Dict keyed by node to shortest path length from source.
- Raises
- NodeNotFound
If
source
is not inG
.
Notes
Edge weight attributes must be numerical. Distances are calculated as sums of weighted edges traversed.
The weight function can be used to hide edges by returning None. So
weight = lambda u, v, d: 1 if d['color']=="red" else None
will find the shortest red path.Examples
>>> G = nx.path_graph(5) >>> length = nx.single_source_dijkstra_path_length(G, 0) >>> length[4] 4 >>> for node in [0, 1, 2, 3, 4]: ... print(f"{node}: {length[node]}") 0: 0 1: 1 2: 2 3: 3 4: 4