How to append a plot to an existing pdf file

You could use recordPlot to store each plot in a list, then write them all to a pdf file at the end with replayPlot. Here's an example:

num.plots <- 5my.plots <- vector(num.plots, mode='list')for (i in 1:num.plots) {    plot(i)    my.plots[[i]] <- recordPlot()}graphics.off()pdf('myplots.pdf', onefile=TRUE)for (my.plot in my.plots) {    replayPlot(my.plot)}graphics.off()

If you are willing to install the small, free, platform-independent pdftk utililty, you could use a system call from R to have it stitch all of your figures together:

## A couple of example pdf docspdf("Append to me.1.pdf")plot(1:10,10:1)dev.off()pdf("Append to me.2.pdf")plot(1:10,rep(5,10)) dev.off()## Collect the names of the figures to be glued togetherff <- dir(pattern="Append to me")## The name of the pdf doc that will contain all the figuresoutFileName <- "AllFigs.pdf"## Make a system call to pdftksystem2(command = "pdftk",        args = c(shQuote(ff), "cat output", shQuote(outFileName)))## The command above is equiv. to typing the following at the system command line## pdftk "Append to me.1.pdf" "Append to me.2.pdf" cat output "AllFigs.pdf"

This is horribly hacky and probably belies my limited UNIX shell fu, but it works for me on a Fedora 17 box with the pdfjam package installed (not an R package, but from the YUM repos)

pdf("pdf1.pdf")plot(1:10)dev.off()pdf("| pdfjoin --outfile \"pdf2.pdf\" && pdfjoin pdf1.pdf pdf2.pdf --outfile pdf1.pdf && rm pdf2.pdf")plot(10:1)dev.off()

The output in R is:

> pdf("| pdfjoin --outfile \"pdf2.pdf\" && pdfjoin pdf1.pdf pdf2.pdf --outfile pdf1.pdf && rm pdf2.pdf")## && pdfunite joined.pdf tmp.pdf joined.pdf && rm tmp.pdf")> plot(10:1)> dev.off()          ----  pdfjam: This is pdfjam version 2.08.  pdfjam: Reading any site-wide or user-specific defaults...          (none found)  pdfjam: No PDF/JPG/PNG source specified: input is from stdin.  pdfjam: Effective call for this run of pdfjam:          /usr/bin/pdfjam --fitpaper 'true' --rotateoversize 'true' --suffix joined --outfile pdf2.pdf -- /dev/stdin -   pdfjam: Calling pdflatex...  pdfjam: Finished.  Output was to 'pdf2.pdf'.          ----  pdfjam: This is pdfjam version 2.08.  pdfjam: Reading any site-wide or user-specific defaults...          (none found)  pdfjam: Effective call for this run of pdfjam:          /usr/bin/pdfjam --fitpaper 'true' --rotateoversize 'true' --suffix joined --outfile pdf1.pdf -- pdf1.pdf - pdf2.pdf -   pdfjam: Calling pdflatex...  pdfjam: Finished.  Output was to 'pdf1.pdf'.null device           1

Basically, pdfjoin will take input from stdin if it is the only input file so I pipe the output from pdf() to the pdfjoin program and specify the output file using the --outfile argument. Then using && is join the original pdf1.pdf with the pdf2.pdf just created, specifying that the output PDF is pdf1.pdf, the name of the original PDF.