cross-platform zip file creation

Question

hi all, i'd like to create a zip archive from within R, and need maximal cross-platform compatibility, so I would prefer not to use a system("zip") command.

Within utils there's zip.file.extract (aka unzip), which uses [a lot of] c code, derived from zlib 1.1.3 within a file called dounzip.c I couldn't find any similar capabilities for creating zip files.

it's also tricky to construct a specific google query for "cran create zip" or equivalent!

Also, a tar will not suffice, I need to creating zip's to use as input for another set of non-R tools.

i'd appreciate any pointers?

cheers, mark

Answer 1

As usual the amazing Omega Project for Statistical Computing is a valuable resource! Take a look at the Rcompression package and try, for example, something like:

?gzip    
txt <- paste(rep("This is a string", 40), collapse = "\n")
v <- gzip(txt))
writeBin(v, "test.txt.zip")

HTH

Answer 2

I think the command gzfile() may also do what you're looking for. Also note that in the upcoming version 2.10.0 there are some enhancements to compression functions that may be relevant. (see https://svn.r-project.org/R/trunk/NEWS -- the svn server may ask you to accept a certificate)