[R] using loops to create multiple images

[Donatas G.]

I have a data.frame with ~100 columns and I need a barplot for each column 
produced and saved in some directory.

I am not sure it is possible - so please help me.

this is my loop that does not work...

vars <- list (substitute (G01_01), substitute (G01_02), substitute (G01_03), 
substitute (G01_04))
results <- data.frame ('Variable Name'=rep (NA, length (vars)), 
check.names=FALSE)
for (i in 1:length (vars))  {
barplot(table(i),xlab=i,ylab="Nuomonės")
dev.copy(png, filename="/my/dir/barplot.i.png", height=600, width=600)
dev.off()
}

questions: 

Is it possible to use the i somewhere _within_ a file name? (like it is 
possible in other programming or scripting languages?)

Since I hate to type in all the variables (they go from G01_01 to G01_10 and 
then from G02_01 to G02_10 and so on), is it possible to shorten this list by 
putting there another loop, applying some programming thing or so? 

-- 
Donatas Glodenis
http://dg.lapas.info