[R] plot merging/compression with R

[Walther, Alexander]

Dear list,

i just encountered a problem concerning the export of multiple plots. is
it possible to merge several PNGs into one PDF document? i know that
this could be easily done by pdf(), but the outcome of this is /way/ too
huge (> 15 MB, four plots) and to my knowledge there's no way to
compress PDFs directly in R. Hence the PNGs that are saved one at a time
and afterwards merged by Adobe Acrobat.  Since i would like to
automatize this process, can this be done by R? Alternatively, is there
a way to compress a PDF of multiple pages right away?

cheers

Alex