[R] R package creation: Confused about how to handle text data

Uwe Ligges ligges at statistik.tu-dortmund.de
Sat Jan 10 16:42:54 CET 2015

You do not want to access these data files by standard mechnisms, and 
that's what the ./data folder is good for. See Writing R Extensions, it 
suggests to use the ./extdata directory in your case, then the data is 
unchanged and you can access those data by your own functions.

Uwe Ligges

On 09.01.2015 09:32, Marine Rohmer wrote:
> Dear R team,
> I am currently creating my first R package and I am getting confused
> with the way to handle text data.
> I've well understood that datasets have to be placed in the ./data
> subdirectory, saved into one of the .rda, .txt or .csv format, and then
> can be loaded with the data() function.
> However, the data() function is the same as the read.table() function,
> that is to say it reads the text file (.txt or .csv) and loads it into a
> data.frame.
> That is not what I want : I just want to access to my text file (.txt or
> .csv) and load it with my own reading function that I developped in my R
> source code of the package. (it's a special reading function with
> special checks according to what the package expects).
> After reading plenty of topics on the web, I found the system.file()
> function useful and used it in this way, in my test file:
> current_dir=system.file(package="MYPACKAGE")
> myTextFile=paste(current_dir,"/data/myTextFile.csv",sep="")
> # Then I use my own function to load it:
> myOwnReadingFunction(myTextFile)
> This worked fine and my "R CMD check" went well.... Until I follow the
> advise of the R CMD check log:
> "Note: significantly better compression could be obtained by using R CMD
> build --resave-data"
> Tiping "R CMD build --resave-data" before "R CMD check" moves my .csv
> files into .csv.bz2 and .csv.xz!
> So that what I wrote in my test file (see above) now does not work.
> Of course I guess I could, for example, change it by:
> myTextFile=paste(current_dir,"/data/myTextFile.csv.bz2",sep="")
> But I really wonder if this is the good way to handle text files in a R
> package. This seems to me a little "tricky".
> Is this a "good practice"?
> Isn't another way to simply access to text files without loading it?
> Have someone already had the same situation?
> Bonus question: why doesn't "R CMD build --resave data" use the same
> compression for my two .csv files? (that is: .bz2 and .xz)
> Thank you in advance for your advices,
> Kind regards,
> Marine
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