[igraph] Can not plot community structure

[Zhige Xin]

Hi I tried to plot the community structure by using label propagation algorithm but got some errors. First, the value of modularity is none. Second, it produced IndexError: color index must be non-negative.

My idea:

1. Read from a csv file with the format of weighted adjacency matrix 

2. Convert the data into a graph object in igraph

3. Applying label propagation algorithm to find communities

4. Plot the result

My code is following:

from igraph import *

from numpy import genfromtxt

import numpy as np

my_data = genfromtxt('CBSNews.csv', delimiter=',')

conn_indices = np.where(my_data)

weights = my_data[conn_indices]

edges = zip(*conn_indices)

g = Graph(edges=edges, directed=False)

g.es['weight'] = weights

result = g.community_label_propagation()

print result.modularity

plot(result)

The erros message is:

Traceback (most recent call last):

  File "plot_community.py", line 25, in <module>

    plot(result)

  File "/usr/local/lib/python2.7/site-packages/igraph/drawing/__init__.py", line 475, in plot

    result.show()

  File "/usr/local/lib/python2.7/site-packages/igraph/drawing/__init__.py", line 316, in show

    self.redraw(ctx)

  File "/usr/local/lib/python2.7/site-packages/igraph/drawing/__init__.py", line 269, in redraw

    plotter(ctx, bbox, palette, *args, **kwds)

  File "/usr/local/lib/python2.7/site-packages/igraph/clustering.py", line 509, in __plot__

    return self._graph.__plot__(context, bbox, palette, *args, **kwds)

  File "/usr/local/lib/python2.7/site-packages/igraph/__init__.py", line 3152, in __plot__

    drawer.draw(self, palette, *args, **kwds)

  File "/usr/local/lib/python2.7/site-packages/igraph/drawing/graph.py", line 259, in draw

    vertex_builder = vertex_drawer.VisualVertexBuilder(graph.vs, kwds)

  File "/usr/local/lib/python2.7/site-packages/igraph/drawing/metamagic.py", line 222, in __init__

    values = self._collect_attributes(attr_spec)

  File "/usr/local/lib/python2.7/site-packages/igraph/drawing/metamagic.py", line 340, in _collect_attributes

    result = [transform(x) for x in result]

  File "/usr/local/lib/python2.7/site-packages/igraph/drawing/colors.py", line 93, in get

    raise IndexError("color index must be non-negative")

I do appreciate it if anyone can help.

Best,

Zhige