Donatas G. wrote:
> 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?)
Oh yes, very easy. two options:
1) Use sprintf, e.g. filename=sprintf("/my/dir/barplot.%d.png",i)
2) Use paste, i.e., filename=paste('/my/dir/barplot.',i,'.png',sep='')
> 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?
Well sure! Just loop over each column of your data frame. The column
names are gotten from the names() function. I don't see a data frame in
your code so I assume d is below:
for (i in names(d)){
barplot(d[,i],filename=sprintf("/my/dir/barplot.%s.png",i))
}
Notice that names(d) returns a character vector, thus i is a string,
whereas in my sprintf example in 1) presumed it an int. Also, be sure to
read up on the apply family of functions as an alternative to using
loops in R code.
Jeff
--
http://biostat.mc.vanderbilt.edu/JeffreyHorner
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