[R-pkg-devel] How to write example results to a tempdir()?

[Sarah Goslee]

Don't change the working directory! That has all kinds of unpleasant
side effects for the unsuspecting user, possibly even more so than
writing to a file.

Instead, write the file to the temp directory, and read it from there, with e.g.

wd <- tempdir()
write(dat, file.path(wd, 'Ttest_1981-2000.dat'))

Using file.path() means that the appropriate path delimiter for that
OS will be used.

Sarah


On Wed, Apr 25, 2018 at 12:30 PM, Jose A Guijarro <jguijarrop at aemet.es> wrote:
> Dear all,
>
> I am struggling to update my package climatol from version 3.0 to 3.1.
> The old version had all examples under a "dontrun" section because they
> needed files created by other examples that the user had to run first.
>
> As this is not acceptable anymore, I made the examples runnable and
> prepared small ad-hoc datasets, but then writing files to the user space
> is against the CRAN policy rules, and I was suggested to run them on a
> temporal directory. Therefore I changed all my examples to read/write
> files to a tempdir(), as in:
>
> \examples{
> #Set a temporal working directory and write input files:
> wd <- tempdir()
> setwd(wd)
> data(Ttest) #(This loads matrix 'dat' and data.frame 'est.c')
> write(dat,'Ttest_1981-2000.dat')
> write.table(est.c,'Ttest_1981-2000.est',row.names=FALSE,col.names=FALSE)
> rm(dat,est.c) #remove loaded data from memory space
> #Now run the example:
> dd2m('Ttest',1981,2000)
> #Input and output files can be found in directory:
> print(wd)
> }
>
> But now CRAN checks return this warning ten times (one for every example
> in the package):
>
> Warning: working directory was changed to ‘/tmp/RtmpWSRK2F’, resetting
>
> Any hint on how to solve the problem will be highly appreciated...
>
> Jose
>


-- 
Sarah Goslee
http://www.functionaldiversity.org