[igraph] Number of isolated nodes in the network

[Claudia Muller-Birn]

Dear all,

I might have a fairly simple question but I have difficulties to solve my 
problem this time. I'd like to compute the number of isolates nodes in a 
network. This function is available in the sna package which I normally avoid 
to use. And now I know once again why:

Error: cannot allocate vector of size 902.3 Mb

Okay, but let's start from the beginning, here are my commands:

library(igraph)
library(sna)

path <- 'timeframe40_edgelist.ncol'

el <- matrix(scan(path), byrow=TRUE, ncol=3)
g <- as.edgelist.sna(el)
i <- isolates(g, diag=FALSE)
length(i)

My edge list has the following format (extract):

4372  4375  2
4372  4372  1
4375  4372  2
4375  4375  6

Well, I'd really appreciate if anyone has an idea what I can do.

Thank you.

Claudia