[R] R packages and assess to data in packages

[Uwe Ligges]

Sharpie wrote:
> 
> Tariq Perwez wrote:
>> Hi Everyone,
>>
>> I have two very basic questions and would appreciate your help.
>> 1. I would like to see/access the data that comes with a given R package
>> by
>> using a function like read.table(). For example, I just installed car
>> package from CRAN. I know that somewhere within the package, there is
>> Duncan.txt file. 
>>
> 
> This is not necessarily true.  Most packages distribute data sets in the
> .rda format.  Text files are usually only distributed if the package
> implements some method of parsing them, such as the example .xml files in
> the XML package.
> 
> 
> 
> Tariq Perwez wrote:
>> I would not only like to look at it from file browser (or
>> using ls command in shell)  but also to access it as:
>>
>>> Duncan <- read.table("path/to/data/Duncan.txt", header = T)
>> I can certainly use:
>>
>>> data(Duncan)
>> and
>>
>>> attach(Duncan)
>> after loading the package car. However, I would like to see all the data
>> that come with a package as separate files. Where are these files located?
>> I
>> installed the car package under Mac OSX  under the user level (if this
>> detail is important). However, I do use R under Ubuntu linux also and
>> general solution to this problem will be great. 
>>
> 
> The system.file() command provides a platform-independent method for
> recovering the path to files distributed in packages.  For example, to list
> all files in the "data" folder of the car package:
> 
>   system.file( 'data', package = 'car' )


Well, not quite platform independent. For an installed package under 
Windows, the data files might be zipped in a container given some 
heuristics is fulfilled and the package maintainer has not explicitly 
asked declared ZipData=no in the DESCRIPTION file of a package.

Uwe Ligges


> To get the path to the .rda file containing all the datasets:
> 
>   system.file( 'data', 'Rdata.rda', package = 'car' )
> 
> 
> Tariq Perwez wrote:
>> I even downloaded the car binaries and unpacked the zipped file on desktop
>> but I just see .rda files
>> within the data folder; there are no .txt files anywhere.  I do see
>> Duncan.rda file (I believe this contains the Duncan.txt data). How can I
>> access the data files from such package, say using a text editor??
>>
> 
> Package datasets are usually only distributed as binary .Rda files.  If you
> want to view them using a text editor you will have to translate them to a
> plain text format-- something like load() followed by write.csv().
> 
> 
> 
> Tariq Perwez wrote:
>> 2. What is the safest/preferred place to install an R package that I want
>> to
>> delete/remove once I do not need it. Sometimes, I just need to install a
>> package from a book's website so that I can work on the exercises etc but
>> do
>> not need the package permanently hanging around. Removing such a package
>> and
>> all the associated files etc would be nice.
>>
>> I would appreciate any help and comments on my questions. Regards,
>>
>> Tariq
>>
> 
> Just install it normally.  You can remove it by running:
> 
>   R CMD REMOVE packageName
> 
>>From the command line.
> 
> Hope this helps!
> 
> -Charlie
>