[R] Problem with colormodel in pdf driver

[Luis Torgo]

I'm trying to create figures in PDF that use the 'gray' colormodel 
instead of the default 'RGB' model, by requirements of a publisher.

My problem has to do with the fact that I'm not being able to get gray 
colors with this option on the pdf() driver. Here is a small example for 
problem replication:

 > R.version
               _                          
platform       i486-pc-linux-gnu          
arch           i486                       
os             linux-gnu                  
system         i486, linux-gnu            
status                                    
major          2                          
minor          8.1                        
year           2008                       
month          12                         
day            22                         
svn rev        47281                      
language       R                          
version.string R version 2.8.1 (2008-12-22)

 > pdf('exp.pdf',colormodel='gray')
 > barplot(table(subset(iris,Petal.Width>1)$Species))
 > dev.off()

Contrary to what I was expecting the bars appear in black and not gray 
as they are supposed to. This is not particularly serious for this toy 
graph but for others it creates more problems.

Interesting enough this problem does not occur with the same option on 
the postscript() driver as it can be observed by running:
 > postscript('exp.eps',colormodel='gray')
 > barplot(table(subset(iris,Petal.Width>1)$Species))
 > dev.off()

Any help is most appreciated.

Luis Torgo

-- 
Luis Torgo
   FEP/LIAAD - INESC Porto, LA   Phone : (+351) 22 339 20 93
   University of Porto           Fax   : (+351) 22 339 20 99
   R. de Ceuta, 118, 6o          email : ltorgo at liaad.up.pt
   4050-190 PORTO - PORTUGAL     WWW   : http://www.liaad.up.pt/~ltorgo