Hi Gabor, Thanks for your reply.
Here are 4 different commands and their result, I guess I am just a bit confused how they relate to each other. The first two are using the cluster_leading_eigen alone, the second two use that command to find the communities and then the modularity function to get the modularity value out of it Would I be right in understanding that cluster_leading_eigen only uses the weights argument after the communities have been found - but then why does it return the same value below for the first two commands - and why is it different to the third command Thanks > cluster_leading_eigen(net, weights = E(net)$weight) IGRAPH clustering leading eigenvector, groups: 2, mod: 0.055 + groups: $`1` [1] "YV" "B" "P" $`2` [1] "DG" "V" > cluster_leading_eigen(net, weights = NULL) IGRAPH clustering leading eigenvector, groups: 2, mod: 0.055 + groups: $`1` [1] "YV" "B" "P" $`2` [1] "DG" "V" > modularity(net,membership(cluster_leading_eigen(net, weights = > E(net)$weight)),weights=NULL) [1] 0.03061224 > modularity(net,membership(cluster_leading_eigen(net, weights = > E(net)$weight)),weights=E(net)$weight) [1] 0.0546875 > On 25 May 2017, at 06:51, Gábor Csárdi <[email protected]> wrote: > > IIRC the original algorithm can be extended easily to take weights > into account. > > If you think the igraph is not doing that (and the docs say that it > would), can you please provide a small example that gives you the same > results with or without (large enough) weights? Thanks. > > Gabor > > On Wed, May 24, 2017 at 10:11 AM, Edmund Hunt <[email protected]> wrote: >> Hello, >> >> I have a question/comment about the leading.eigenvector.community function >> in igraph >> >> It has an argument for weights, but this seems to make no difference to the >> calculated clusters/resulting modularity >> >> Indeed I don’t think Newman’s algorithm takes edge weights into account? >> >> Is it the case that the weights are only used after the community detection >> has taken place, to calculate a modularity value? Is it appropriate to use >> the weights to calculate modularity, can anyone advise me what is the >> ‘right’ thing to do with a weighted, undirected network - is it definitely >> to use the weights in the modularity calculation, or is there a free choice >> >> Perhaps these issues could be made clearer in the function help >> >> Thanks >> >> _______________________________________________ >> igraph-help mailing list >> [email protected] >> https://lists.nongnu.org/mailman/listinfo/igraph-help >> > > _______________________________________________ > igraph-help mailing list > [email protected] > https://lists.nongnu.org/mailman/listinfo/igraph-help
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