Re: [Rd] Small modification of zip.file.extract in utils?

From: Martin Elff <>
Date: Sat, 01 Nov 2008 12:09:07 +0100

On Thursday 30 October 2008 (20:08:27), Jon Olav Skoien wrote:
> Dear list,
> I needed to extract a zip-archive, and found zip.file.extract in utils.
> My only problem was the use of tempdir(), since I wanted to permanently
> extract the archive at a fixed location for later use. My own fix was
> simple, adding an extra parameter zipdir (without default), and within
> the function change
> tmpd <- tempdir()
> to
> tmpd = ifelse(missing(zipdir),tempdir(),zipdir)
> This modification could maybe be useful also for other users, unless
> there are some problems I am not aware of?

I had similar problems with 'zip.file.extract' and implemented a function 'unzip' in my package 'memisc', which also works in a way that is probably more comprehensible for end-users like me:

unzip                 package:memisc                 R Documentation

Extract Files from Zip Files


     'unzip' extracts a file from a zip archive and puts them into a
     directory specified by the user or into the temporary directory of
     the current session.




 zipfile: a character string, the path to the zip file.

    item: a character string, full path (from the root of the zip file)

          to the file to extract.

     dir: path to the directory were to place the extracted file.

 package: optional package name, if given, the path to the zipfile

          starts in the package's root directory.


     # Extract American National Election Study of 1948
     # It is item "NES1948.POR" in zip file "anes/NES1948.ZIP"
     # where this path is relative to the packages'
     # root directory.
     nes1948.por <- unzip("anes/NES1948.ZIP","NES1948.POR",

All the best,

Martin mailing list Received on Sat 01 Nov 2008 - 11:16:02 GMT

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