R help - Jan 2010 - Rscript is not loading some of one of the standard R packages

Hi,


I have a script I can run step by step through the R interpreter and it works
fine. I then run as a shell script with Rscript and it fails.


The error message comes when I am creating a model matrix with
model.matrix.default().


Error in `contrasts<-`(`*tmp*`, value = "contr.Treatment") : 
  could not find function "is"
Calls: model.matrix.default -> contrasts<-


I included the following command at the beginning of my Rscript : 


cat("Looking for environment(is): ", environment(is), "\n")


and I received the same error message:


Error in environment(is) : object 'is' not found
Calls: cat -> environment




At the command line (through the R interpreter) the same command
returns:
> environment(is)
<environment: namespace:methods>


Rscript is not loading the methods package and I don't know how to fix this.


Why would this be happening and how can I prevent it in the future?




I am running the following R session at the command
line:
> sessionInfo()
R version 2.10.1 (2009-12-14) 
x86_64-pc-linux-gnu 

locale:
 [1] LC_CTYPE=en_CA.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_CA.UTF-8        LC_COLLATE=en_CA.UTF-8    
 [5] LC_MONETARY=C              LC_MESSAGES=en_CA.UTF-8   
 [7] LC_PAPER=en_CA.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_CA.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

Here is what I get when I run sessionInfo() from Rscript

R version 2.10.1 (2009-12-14) 
x86_64-pc-linux-gnu 

locale:
 [1] LC_CTYPE=en_CA.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_CA.UTF-8        LC_COLLATE=en_CA.UTF-8    
 [5] LC_MONETARY=C              LC_MESSAGES=en_CA.UTF-8   
 [7] LC_PAPER=en_CA.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_CA.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  base  



The version of Rscript I am running is:
$ Rscript --version
R scripting front-end version 49838





Thank you for your help
Peter


 		 	   		  
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