This documents an unmaintained version of NetworkX. Please upgrade to a maintained version and see the current NetworkX documentation.


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

Compute shortest paths and lengths in a weighted graph G.

Uses Dijkstra’s algorithm for shortest paths.

  • 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.

distance,path – 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.

Return type:



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


Edge weight attributes must be numerical. Distances are calculated as sums of weighted edges traversed.

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).