Re: [igraph] Community in networks with many nodes but low link-density

[Gábor Csárdi]

Hi Charles,

On Wed, Oct 31, 2012 at 9:04 PM, Charles Novaes de Santana
<address@hidden> wrote:
> Dear igraph-users,
>
> I am trying to study the modularity of networks with many nodes but
> low link-density (48082 nodes and 12869 edges). I tried to use
> walktrap.community and fastgreedy.community functions, but those
> methods didn't work (segmentation fault).

really? They might give an error, but they should not segfault. Which
version of igraph is this?

> I also tried the
> edge.betweenness.community and it works, but of course it is very
> slow.

Well, yes, this is kind of expected.

> Just for curiosity: which of the implemented methods do you suggest me
> to use? Am I right in using the edge.betweenness?

I would check the fastgreedy and the spinglass algorithms, these tend
to give better results in terms of modularity (if that's what you are
going for), with the newest version of igraph (0.6.x).

Maybe it would be better to extract the connected components from your
graph, and run the algorithm(s) of them. It does not really make sense
to run community detection on a disconnected graphs, at least not the
algorithms that are currently implemented in igraph.

Best,
Gabor

> Thanks in advance for any help.
>
> Best,
>
> Charles
>
> --
> Um axé! :)
>
> --
> Charles Novaes de Santana
> http://www.imedea.uib-csic.es/~charles
> PhD student - Global Change
> Laboratorio Internacional de Cambio Global
> Department of Global Change Research
> Instituto Mediterráneo de Estudios Avanzados(CSIC/UIB)
> Calle Miquel Marques 21, 07190
> Esporles - Islas Baleares - España
>
> Office phone - +34 971 610 896
> Cell phone - +34 660 207 940
>
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-- 
Gabor Csardi <address@hidden>     MTA KFKI RMKI