[R] Absolute path in gdata library

[Prof Brian Ripley]

On 07/11/2012 23:12, Marc Schwartz wrote:
> On Nov 7, 2012, at 4:58 PM, r <ric.romoli at gmail.com> wrote:
>
>> Dear list, I have some .xls files that I need to read into R. I am
>> able to do so using read.xls in the gdata package, however the
>> helper functions sheetNames and sheetCount fail. This is the
>> error:
>>
>> Unable to open file '~/SharedFolder/MyData/mydata.xls'. Warning:
>> running command ''/usr/bin/perl'
>> '/usr/local/lib/R/site-library/gdata/perl/sheetCount.pl'
>> '~/SharedFolder/MyData/mydata.xls'' had status 2
>>
>> Googling I found that the problem is caused by the use of the
>> absolute path ("~/SharedFolder/MyData/") instead of
>> "/home/r/SharedFolder/MyData/". I use the absolute path because I
>> work from different computer connected to a shared folder.

>>
>> This is the discussion I found:
>> http://stackoverflow.com/questions/11737906/path-specification-when-using-the-r-package-gdata
>>
>>
>>
Is there a way to solve this problem??
>>
>> Best Riccardo
>
>
> You can contact the package maintainer (cc'd here) and suggest that
> the use of:
>
> normalizePath()
>
> be implemented in the code, which would then do tilde expansion, etc.
> when relative file paths are passed rather than absolute paths are
> used.

If you just want tilde expansion, it is usually better to use path.expand().

normalizePath() is more drastic and can lead to paths the user will not 
recognize on file systems with complex use of links.

R itself uses normalizePath() only where it needs to work hard to check 
that paths are the same.  One instance is .libPaths() (and it has led to 
puzzlement there).

>
> A workaround for now, would be to wrap your filename in that function
> in your code, so that when you use relative paths, the appropriate
> expansion is used and passed to the gdata function as the filename
> argument.
>
> I just made this change myself in the WriteXLS package at the request
> of another useR.
>
> Regards,
>
> Marc Schwartz
>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595