networkx.single_source_dijkstra

single_source_dijkstra(G, source, target=None, cutoff=None, weight='weight')

Compute shortest paths and lengths in a weighted graph G.

Uses Dijkstra’s algorithm for shortest paths.

Parameters:

G : NetworkX graph

source : node label

Starting node for path

target : node label, optional

Ending node for path

cutoff : integer or float, optional

Depth to stop the search. Only paths of length <= cutoff are returned.

Returns:

distance,path : dictionaries

Returns a tuple of two dictionaries keyed by node. The first dictionary stores distance from the source. The second stores the path from the source to that node.

See also

single_source_dijkstra_path, single_source_dijkstra_path_length

Notes

Distances are calculated as sums of weighted edges traversed. Edges must hold numerical values for Graph and DiGraphs.

Based on the Python cookbook recipe (119466) at http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/119466

This algorithm is not guaranteed to work if edge weights are negative or are floating point numbers (overflows and roundoff errors can cause problems).

Examples

>>> G=nx.path_graph(5)
>>> length,path=nx.single_source_dijkstra(G,0)
>>> print length[4]
4
>>> print length
{0: 0, 1: 1, 2: 2, 3: 3, 4: 4}
>>> path[4]
[0, 1, 2, 3, 4]