CODEWITHSUNDEEP
python-3.xnetworkx
MissBleu
MissBleu

Reputation: 175

networkx and dict_values causing float argument error

I am trying to follow the tutorial given here code posted below for "reproducibility" but I get stuck when I try the draw() for the first visualization

import networkx as nx
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors
def draw(G, pos, measures, measure_name):
    nodes = nx.draw_networkx_nodes
        (G, pos, node_size=250,cmap=plt.cm.plasma, 
        node_color=measures.values(),
        nodelist=measures.keys())
    nodes.set_norm(mcolors.SymLogNorm(linthresh=0.01, linscale=1))
    edges = nx.draw_networkx_edges(G, pos)
    plt.title(measure_name)
    plt.colorbar(nodes)
    plt.axis('off')
    plt.show()
G = nx.karate_club_graph()
pos = nx.spring_layout(G)
draw(G, pos, nx.degree_centrality(G), 'Degree Centrality')

The traceback keeps showing the error: float() argument must be a string or a number, not 'dict_values'

based on this question

I think that it is a python 3 problem. I tried

draw(G, np.array(list(pos.values())).astype(float), 
nx.degree_centrality(G), 'Degree Centrality')

but I am still getting the same error. Any advice?

Upvotes: 0

Views: 891

Answers (1)

abc
abc

Reputation: 11929

The code works fine with python2.7.
The reason is the type of measures.values() which is different between Python 2 and 3.
Indeed, while in python 2.7 dict.values returns list, in python 3.x it returns a view of the dictionary’s values.

d={"k":"v"}
#python 2.7
type(d.values())  --->  <type 'list'>
#python 3.x
type(d.values())  --->  <class 'dict_values'>

Thus, you have a TypeError exception raised as node_color is expected to be a string or an array of floats and the argument has type dict_values. See the documentation here for more details.

To solve the problem you only need to change the way the node colors are passed to the draw_networkx_nodes function.
For instance, you could use a list as follows:

nodes = nx.draw_networkx_nodes(G, pos, node_size=250, cmap=plt.cm.plasma, node_color=list(measures.values()),nodelist=measures.keys())

Upvotes: 3

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