Hello, > After computing a set of communities, using a multi-cut algorithm like > infomap.community(), I understand it computes the modularity of the best > (highest modularity) community. Errrmm… not sure if we are completely on the same page here, so let me try to clarify things and sorry if I’m stating the obvious.
First of all, modularity is a measure that quantifies the quality of a community structure “as a whole”, so there is no such thing as the modularity of a single community - the measure always refers to the quality of the entire partition. Actually, the formula of the modularity measure can be rearranged such that the outermost sum in the formula iterates over each of the communities one by one, so one could theoretically say that whatever is within the outermost sum is the modularity of an individual community, but the problem is that the individual contributions of the communities to the modularity score as a whole are not normalized; larger communities contribute more to the modularity score than small ones. If you are looking for a measure that helps you to select the “important” communities out of a community structure that infomap.community or whatever other algorithm gives to you, read the following paper - I think it’s a good starting point: http://arxiv.org/abs/0907.3708 The measure that the authors describe in this paper is not implemented in igraph, but they seem to provide their own implementation. All the best, Tamas _______________________________________________ igraph-help mailing list [email protected] https://lists.nongnu.org/mailman/listinfo/igraph-help
