Hi Alireza, Thank you so much for your reply. I'm not sure whether concave hull of the community would be the solution here or not , (by what do we mean by boundary ). here I meant that one vertex is in one community and the, other one is in the other community, and I would like to calculate the number of the edges between these two vertices for each community.
Regards, Fatemeh ᐧ On Thu, Nov 27, 2014 at 10:25 AM, Alireza Norouzzadeh < [email protected]> wrote: > Hi! > > On solution is to find the concave hull of the community. Then count the > number of edges. > This is not in igraph. But there are solutions in c++, R as far as i know. > > Regards > Alireza > > >> Date: Tue, 25 Nov 2014 23:52:52 +0330 >> From: Fatemeh a <[email protected]> >> To: Help for igraph users <[email protected]> >> Subject: [igraph] calculating the number of edges on the boundary of S >> Message-ID: >> <CABzwCXNNrWvKqY= >> [email protected]> >> Content-Type: text/plain; charset="iso-8859-1" >> >> >> Hi, >> >> I would appreciate if some one could help me to speed up this piece of >> code >> : >> >> what I am trying to do is to calculate the number of edges on the boundary >> of community S but it is really slow. >> >> numberofedge<-function(graph,community) >> { >> cs <- data.frame(combn(unique(membership(community)),2)) #----considering >> a >> combination of communities two by two >> cx <- sapply(cs, function(x) { #calculating edges in between two >> communities >> es<-E(graph)[V(graph)[membership(community)==x[1]] %--% >> V(graph)[membership(community)==x[2]]] >> length(es)}) >> y=cbind(t(cs),cx) >> i=1 >> CS=array( data=0,dim = length(unique(membership(community)))) >> while (i<length(y[,1])+1){ # calculating the edges on the boundary for >> each community >> CS[y[i,1]]=CS[y[i,1]]+y[i,3] >> CS[y[i,2]]=CS[y[i,2]]+y[i,3] >> i=i+1 >> } >> >> >> -- >> regards >> F..A >> >> > _______________________________________________ > igraph-help mailing list > [email protected] > https://lists.nongnu.org/mailman/listinfo/igraph-help > > -- regards F..A
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