[Qgis-developer] More ideas about package installation in R for SEXTANTE

[Victor Olaya]

Hi all

We have been discussing some issues with packages in R, and I would
like to share some ideas wth you

The goal is to make package installation as easy and practical as
possible, so scripts can run with minor settings

I am thinking that a good solution would be to check for packages
needed by a script, checking calls to library(). With that, package
installation commands could be included, as it is done now with rgdal
and raster, with a code like this

'tryCatch(find.package("rgdal"), error=function(e)
install.packages("rgdal", dependencies=TRUE))')

replace "rgdal" with the lib the script uses...and it should be fine, right?

two problems in here:

1) if the user has no permissions that will not work, but I can
implement a way of checking what is needed and what is installed in
case the algorithm fails, so I can inform the user to manually install
the reuqired packages

2)to avoid installing things automatically, for users that might not
like that behaviour, this can be turned off, so manual intallation is
required.

All this would go on the default lib path, since we agreed that it is
a better option than having a custom one that might duplicate packages

Comments are welcome

Thanks in advance!

Victor