[R] using loops to create multiple images

Deepayan Sarkar deepayan.sarkar at gmail.com
Mon Aug 6 02:23:59 CEST 2007

On 8/4/07, Donatas G. <dgvirtual at akl.lt> 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?)

(Yes, but) Why are you using dev.copy? See ?png, in particular how the
``page number'' can be encoded in the 'filename' argument for
multi-page output.


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