Python - TypeError: function takes 3 positional arguments but 4 were given

Question

I am trying to add edges between the cities and dictionary with the distance between them. When I try to compile the code I get to this error, can anyone help me?

import networkx as nx

cities = nx.Graph()
cities.add_edge('San Diego','LA',{'distance':0.4})
cities.add_edge('NY','Nashville',{'distance':5.6})
cities.add_edge('Boston','DC',{'distance':0.8})

Answer 1

I believe your code will work in.networkx 2.0 (it seems to work for me), but not in.networkx 1.11.

In reading through the documentation for.networkx 1.11, it looks like you need to do either

cities.add_edge('Boston', 'Nashville', distance=0.4)

or

cities.add_edge('Boston', 'Nashville', attr_dict = {'distance':0.4})

But I can't easily test it on my machine which has v2.0.

Answer 2

If you want to use a dictionary for attributes then you can do it with @Joel second example

cities.add_edge('Boston', 'Nashville', attr_dict = {'distance':0.4})

however in this case you will get 'attr_dict' as an attribute in which you will have your dictionary. Like this.

cities.edges(data=True) 

will return

EdgeDataView([('Boston', 'Nashville', {'attr_dict': {'distance': 0.4}})])

A way to get only your dictionary in attributes is add_edges_from() :

cities.add_edges_from([('San Diego','LA',{'distance':0.4})])
cities.add_edges_from([('NY','Nashville',{'distance':5.6}),
('Boston','DC',{'distance':0.8})])

cities.edges(data=True) 

will return

EdgeDataView([('San Diego', 'LA', {'distance': 0.4}), ('NY', 'Nashville', {'distance': 5.6}), ('Boston', 'DC', {'distance': 0.8})])