Re: [igraph] to attach edge weights

[Gabor Csardi]

The easiest is to use the 'weighted' argument of graph.adjacency:

m<- rbind(c(1, 0.2, 0.6), c(0.2, 1, 0.8), c(0.6, 0.8, 1))
diag(m) <- 0
m[ m<0.5 ] <- 0
g <- graph.adjacency(m, weighted=TRUE)

Although i just noticed that 'weighted' and 'upper' don't work
well together, so if you want to create an undirected graph
here is a workaround:

m<- rbind(c(1, 0.2, 0.6), c(0.2, 1, 0.8), c(0.6, 0.8, 1))
diag(m) <- 0
m[ m<0.5 ] <- 0
m[ lower.tri(m) ] <- 0
g <- graph.adjacency(m, weighted=TRUE, mode="undirected")

Gabor

On Thu, Nov 29, 2007 at 11:42:36AM +0900, MATSUDA, Noriyuki wrote:
> Hello:
> 
>    I'd be happy if any one can tell me how to attach edge weights on
> the basis of a connectedness/similarity matrix.  Suppose I do the
> following for a 3 by 3 correlation matrix
>    m<- rbind(c(1, 0.2, 0.6), c(0.2, 1, 0.8), c(0.6, 0.8, 1))
>    m(diag)<-NA;
>    m[m(a)<0.5] <-0;  m[m(a)>=0.5] <-1  #There must be a better way
>    g<-graph.adjacency(m, mode="upper"] #upper includes diagonals
>    E(g)$weight ???????
> 
> Thanks in advance
> -- 
> MATSUDA, Noriyuki　<in Kanji> 松 田 紀 之
> 
> 
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-- 
Csardi Gabor <address@hidden>    MTA RMKI, ELTE TTK