[igraph] igraph in R/Rscript error

[Michael Krein]

Hello community!

I have (hopefully) a very simple question to you all, but it's leaving 
me very frustrated here.  :-P

I'm trying to call igraph from an Rscript, and the error is as follows:
--
Error in graph.adjacency(c, mode = "undirected", diag = FALSE) :
 could not find function "is"
Execution halted
--

Below is the sample code, which executes fine from the interactive R 
session:
--
library(igraph)

a<-c(1,2,3,4,5,6,7,8,9)
dim(a) <- c(3,3)

b <- as.matrix(dist(a))
c <- (b < 2)

d<-graph.adjacency(c, mode="undirected", diag=FALSE)
print(transitivity(d))
--

And gives me the transitivity/cluster coefficient of 0, which is expected.


I'm using R version 2.9.2 (2009-08-24) for x86-64, on CentOS 5.4 (I'm 
using the R version from the EPEL repository.)
I installed igraph via install.packages("igraph", dependencies=TRUE) 
today, so I believe I am using the current version.


Any help would be much appreciated.

Thanks!
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Michael Krein
Breneman Research Group
Rensselaer Exploratory Center for Cheminformatics Research
Rensselaer Polytechnic Institute
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