nx.shortest_path w/ weight

[ilter yüksel]

Hi all,

I'd like to calculate the shortest path according to edge weight but couldn't succeed. Could you please explain what I miss here?

As far as I know. weight of the edges w/out weight value should be considered as 1. The shortest path should be [0, 1, 2, 3, 4] since the weight of edge 1-5 is assigned as 50. 

import networkx as nx

G = nx.path_graph(5)

G.add_node(5)

print(nx.shortest_path(G, source=0, target=4))

G.add_edge(1,5)

G.add_edge(5,4, weight=50)

print(nx.shortest_path(G,0,4))

print(G.edges.data())

Output;

[0, 1, 2, 3, 4]

[0, 1, 5, 4]

[(0, 1, {}), (1, 2, {}), (1, 5, {}), (2, 3, {}), (3, 4, {}), (4, 5, {'weight': 50})]

Thanks,

İlter

[Ross Barnowski]

According to the [shorest_path docstring](http://networkx.org/documentation/latest/reference/algorithms/generated/networkx.algorithms.shortest_paths.generic.shortest_path.html), the default value for the `weight` attribute is `weight=None`, meaning that edge weight attributes are not considered in the calculation. In order to get the weighted calculation, you must explicitly specify the edge attribute name containing the weights, e.g. `nx.shortest_path(G, source=0, target=4, weight="weight")`

Hope that helps!

[ilter yüksel]

Thanks Ross, it works! 

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--ilter