[Rd] large sysdata.rda file --- strategies?

[Uwe Ligges]

On 07.02.2013 15:41, Dr. Peter Ruckdeschel wrote:
> Hi,
>
> to speed up computations in our RobASt family of packages, we use
> interpolation on a grid of precomputed values which we save together
> with the interpolating functions (results of splinefun essentially)
> in sysdata.rda in the R folder of our pkg.
>
> After adding grids for some more models, this file has grown
> considerably, even after application of tools::resaveRdaFiles.
> At the moment we are at about 2MB (compressed) and 8.8 MB
> (uncompressed) and hence R CMD check --as-cran issues a NOTE.
>
> We want to comply with cran policies,
>        http://cran.r-project.org/web/packages/policies.html
> in particular with
>> Where a large amount of data is required (even after compression),
>> consideration should be given to a separate data-only package which
>> can be updated only rarely (since older versions of packages are
>> archived in perpetuity).
>
> Q1: Are packages only consisting of a sysdata.rda file thinkable for
> submission on CRAN ? Are such pkgs the way to go for w.r.t. to the
> cited policy?

Yes, given this package needs less updates than the main package, one 
should consider such a data only package that needs rare updates and 
does not flood the space with archived versions.


> If this is the case, how  would one document such a package, in particular
> if we do not export any objects in the NAMESPACE file?
> In addition, with a sysdata.rda-only pkg,  R CMD check issues a warning
> "Found directory 'R' with no source files"  Of course a workaround is
> adding a comment-only file comment.R to the R folder.

If the checks will be changed not to warn in such a case, this can only 
happen for R >= 3.0.0, so your workaround to tell the checks you really 
intended such a package with R folder not containing any code sounds 
plausible for now.


> Q2: Is there a lazy load / lazy data mechanism available for
> sysdata.rda ? If so how would one enforce it?

It is lazy loaded. From WRE:
"if the ‘R’ subdirectory contains a file ‘sysdata.rda’ [...] this will 
be lazy-loaded into the namespace/package environment"


Best,
Uwe



> Any suggestions appreciated,
>
> Best, Peter
>