CODEWITHSUNDEEP
pythonnetworkx
Alfredo Bellisario
Alfredo Bellisario

Reputation: 13

Example from NetworkX documentation gets an error (all_pairs_shortest_path)

I tried to copy and paste an example from NetworkX package documentation. This is the example:

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

Unfortunately, instead of the expected output, I get the following error message:

'generator' object has no attribute '__getitem__'

Upvotes: 1

Views: 940

Answers (2)

Joel
Joel

Reputation: 23827

So your error is due to the fact that in Python 2.x many of the methods that used to return dicts now return generators. Among them is all_pairs_shortest_path. You're using this new version of networkx, but looking at an out-of-date tutorial. So the error message you saw comes from the fact that you have a generator path and you're trying to access path[0], which doesn't make sense to Python. The easiest fix here is to simply follow the answer provided by Walter and say

path = dict(nx.all_pairs_shortest_path(G))

In general, when using code that was written for networkx 1.x, but you are using version 2.x, you should consult the migration guide (though in your case it's not particularly useful).

Upvotes: 2

Walter Iannini
Walter Iannini

Reputation: 21

Looks like path is a generator: convert it into a dictionary and it works:

path = dict(nx.all_pairs_shortest_path(G))

Upvotes: 1

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