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

Marine Rohmer Marine.Rohmer at mgx.cnrs.fr
Mon Jan 12 09:42:27 CET 2015

Hi Uwe and Hadley,

Thank you a lot for your answer.
The ./inst/extdata folder seems to work fine, accessing my text files in 
this way :
myFile=system.file("extdata", "myFile.csv", package="MyPackage")
I've read the Writing R Extension so many times without understanding 
well the 1.1.6 section, so thank you for your help, now this seems 
obvious !

Kind regards,


Le 2015-01-10 16:42, Uwe Ligges a écrit :
> 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.
> Best,
> 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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