vertex labels in igraph from adjacency matrix
Looks like I turned an "off my one error" into an "off by two error" by adding rather than subtracting. Clearly a logic error on my part. Also, which.max is clearly superior as it results in half as many function calls. Thanks guys! As an aside, although igraph may use the C indexing convention, R users and their code, is much more in tune with indexing beginning at 1. Adjusting this in the R interface to igraph may solve many headaches down the road. Mark Mark W. Kimpel MD ** Neuroinformatics ** Dept. of Psychiatry Indiana University School of Medicine 15032 Hunter Court, Westfield, IN 46074 (317) 490-5129 Work, & Mobile & VoiceMail (317) 204-4202 Home (no voice mail please) mwkimpel<at>gmail<dot>com ******************************************************************
Gabor Csardi wrote:
On Wed, Mar 05, 2008 at 02:27:21AM -0500, Charilaos Skiadas wrote: [...]
Btw, you will likely want to take the betweenness call out, and call it once and store the result, instead of calling it twice (well, assuming the graph is largish). Or even better, use which.max: which.max(betweenness(graph = my.graph, v=V(my.graph), directed = FALSE))
This is almost good, but there is a catch, in igraph vertices are numbered from zero. So if you want an igraph vertex id, then you need to subtract one from this, i.e.: maxb <- which.max(betweennness(my.graph, directed=FALSE))-1 You can double check it: betweenness(my.graph, maxb, directed=FALSE) Gabor PS. there is also an igraph mailing list, see the igraph homepage at igraph.sf.net
Haris Skiadas Department of Mathematics and Computer Science Hanover College
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