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# dijkstra_path

dijkstra_path(G, source, target, weight='weight')

  Returns the shortest weighted path from source to target in G.

  Uses Dijkstra’s Method to compute the shortest weighted path between two nodes in a graph.

  Parameters:
    G NetworkX graph
    source node

      Starting node

    target node

      Ending node

    weight string 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` to `v` will be `G.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 or None to indicate a hidden edge.

  Returns:
    path list

      List of nodes in a shortest path.

  Raises:
    NodeNotFound

      If `source` is not in `G`.

    NetworkXNoPath

      If no path exists between source and target.

  See also

  `bidirectional_dijkstra`
  `bellman_ford_path`
  `single_source_dijkstra`

  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.

  The weight function can be used to include node weights.

      >>> def func(u, v, d):
      ...     node_u_wt = G.nodes[u].get("node_weight", 1)
      ...     node_v_wt = G.nodes[v].get("node_weight", 1)
      ...     edge_wt = d.get("weight", 1)
      ...     return node_u_wt / 2 + node_v_wt / 2 + edge_wt

  In this example we take the average of start and end node weights of an edge and add it to the weight of the edge.

  The function `single_source_dijkstra()` computes both path and length-of-path if you need both, use that.

  Examples

      >>> G = nx.path_graph(5)
      >>> print(nx.dijkstra_path(G, 0, 4))
      [0, 1, 2, 3, 4]

  Find edges of shortest path in Multigraph

      >>> G = nx.MultiDiGraph()
      >>> G.add_weighted_edges_from([(1, 2, 0.75), (1, 2, 0.5), (2, 3, 0.5), (1, 3, 1.5)])
      >>> nodes = nx.dijkstra_path(G, 1, 3)
      >>> edges = nx.utils.pairwise(nodes)
      >>> list(
      ...     (u, v, min(G[u][v], key=lambda k: G[u][v][k].get("weight", 1)))
      ...     for u, v in edges
      ... )
      [(1, 2, 1), (2, 3, 0)]