On 21/05/12 10:52, Tamás Nepusz wrote:
Well, that's up to you ;) The dendrogram starts with N communities (each vertex in its own community). If you take 1 step, then two communities will be merged, yielding N-1 communities. If you take another step, you get N-2 communities, and so on. If you need, say, 4 communities in the end, you must perform N-4 merges. I guess that you would like to select the "optimal" number of communities with the modularity function, i.e. you want to take the division which yields the highest modularity. In this case, you can simply try steps=1, steps=2, steps=3, …, steps=N-1, calculate the modularity score for each, and keep the best one.
Hi Tamás, thanks for your reply. I'm not really sure if I would like to select the optimal number of communities based on the highest modularities.
All I've used so far is only "ready-made" implementations of the Girvan Neumann algorithm, and I don't remember having had to set the number of steps. All I remember getting was one community assignment presented to me as THE GN clustering for that undirected network.
Would you say that most of these implementations would basically output one "optimal" cluster assignment based the highest modularity function observed? Or based on something else?
Thanks, apologies if this does not make sense. Best Giuseppe -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. _______________________________________________ igraph-help mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/igraph-help
