Thank you Tamas! I've tried what you suggested (it looks exactly what I was looking for) but for some reason it gives me an error: Error: unexpected '==' in "E(g)[V(g)$color == "red" %--% V(g)$color =="
I really don't understand what's wrong... l. ________________________________________ From: igraph-help <igraph-help-bounces+lucr=itu...@nongnu.org> on behalf of Tamas Nepusz <nta...@rmki.kfki.hu> Sent: 11 October 2016 17:09 To: Help for igraph users Subject: Re: [igraph] listing edges connecting nodes with same attributes Hello, Use the "%--%" operator when indexing the edge sequence; see this page for more details (under the heading "Special functions"): http://igraph.org/r/doc/igraph-es-indexing.html Example: g <- grg.game(100, 0.2) V(g)$color <- c("red", "green") E(g)[V(g)$color == "red" %--% V(g)$color == "red"] This will give you all the edges between red nodes; you can then use length() to figure out how many such edges there are. T. On Tue, Oct 11, 2016 at 11:52 AM, Luca Rossi <l...@itu.dk> wrote: > Hello, > > I’m sure this is a very simple question but for some reason I can’t figure > out how to do it. > I need to list all the edges connecting nodes with a specific attribute. > (e.g. nodes can be “red” or “green”). So i want to now how many dyads > red-red, red-green, green-green. > I’ve tried with edge_connectivity but it doesn’t work when source and target > are the same node (as it happens in this case: > > edge_connectivity(g,source = V(g)[V(g)$color == "green"],target = > V(g)[V(g)$color=="green”]) > > > is there any way to do this? > > Thank you ! > > Luca > > > _______________________________________________ > igraph-help mailing list > igraph-help@nongnu.org > https://lists.nongnu.org/mailman/listinfo/igraph-help _______________________________________________ igraph-help mailing list igraph-help@nongnu.org https://lists.nongnu.org/mailman/listinfo/igraph-help _______________________________________________ igraph-help mailing list igraph-help@nongnu.org https://lists.nongnu.org/mailman/listinfo/igraph-help