Re: [R] vertex labels in igraph from adjacency matrix

From: Gabor Csardi <>
Date: Wed, 05 Mar 2008 09:45:38 +0100

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 =
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)


PS. there is also an igraph mailing list, see the igraph homepage at

> Haris Skiadas
> Department of Mathematics and Computer Science
> Hanover College

Csardi Gabor <>    UNIL DGM

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