CODEWITHSUNDEEP
pythonubuntuubuntu-14.04igraphglpk
Abderrahmane Boulgheraif
Abderrahmane Boulgheraif

Reputation: 33

igraph cannot use GLPK

I just wrote a python script to do optimal_modularity using the igraph module, this function makes use of the GLPK library, but I'm getting this error even after installing python-glpk and practically all glpk related packages :

 root@ubuntu:/home/abdou/Desktop/graphs# python graph.py
Traceback (most recent call last):
  File "graph.py", line 49, in <module>
    print g.community_optimal_modularity()
  File "/usr/lib/python2.7/dist-packages/igraph/__init__.py", line 1076, in community_optimal_modularity
    GraphBase.community_optimal_modularity(self, *args, **kwds)
NotImplementedError: Error at optimal_modularity.c:81: GLPK is not available, Unimplemented function call

This is the script :

    from igraph import *


g = Graph()

    g.add_vertex(1)
.
.
.
    g.add_vertex(20)

g.add_edge(1,2)

g.add_edge(12,0)

plot(g)
print g.community_optimal_modularity()
verClus = VertexClustering(g)

plot(verClus.cluster_graph())

Upvotes: 0

Views: 1458

Answers (2)

Thara
Thara

Reputation: 1

I am using clustering methods and get membership instead. Hope this may help for MacOS user since I also had trouble with GLPK.

Upvotes: 0

Tam&#225;s
Tam&#225;s

Reputation: 48071

python-igraph depends on the igraph library, which is written in C. Depending on how you installed python-igraph, it may or may not be compiled with GLPK support. Since the code that uses GLPK from python-igraph is in the C layer, it does not matter if you install GLPK after the compilation of python-igraph or if you install python-glpk; the only thing that matters is whether GLPK was present on your machine when you compiled python-igraph for the first time.

So, assuming that you installed python-igraph using pip and you did not have the C core of igraph in advance on your machine, you will need to:

  1. Uninstall python-glpk (it won't be needed).
  2. Uninstall python-igraph.
  3. Ensure that all the GLPK libraries are installed (make sure to install the development headers as well).
  4. Reinstall python-igraph.

python-igraph should then detect that GLPK itself is installed (look for a line containing GLPK support -- yes or something similar in the early stages when python-igraph downloads the corresponding C core and tries to compile it) and you will be able to use Graph.optimal_modularity() from then on.

Upvotes: 2

Related Questions