[R] load data for mypkg-Ex.R

[Prof Brian Ripley]

On Fri, 27 Feb 2004, Jason Sinnwell wrote:

> Using R 1.7.1 in Solaris
> 
> I'm developing a package for both Splus and R, and I'm trying to use all the 
> same files for R and Splus, both function files and help files.  I have two 
> questions.
> 
> 1) The file made by R CMD check to run .Rd-examples posts examples from files in 
> alphabetical order.  Is it okay/recommended/common-practice to set up all the 
> example data in the first two (alphabetically-sorted) examples and assume that 
> data exists for the rest of the examples?  

That does not work: the workspace is cleared after each help file.  As 
from the next release, the search path is restored too.

> 2)  Since data() is not understood by Splus, I don't want to put a 
> 	     > data(example.data) 
> in the sgml file because then the Splus example would not run as data() doesn't 
> exist there.  Is there a spot I can make sure this data is loaded when running 
> the examples, but not to load the data every time you load the library, as it 
> would take up unnecessary space.  It is a ~~220 x 25 data.frame, is that enough 
> size to worry about this?

Probably not: but use object.size() to find out.
 
> I'm considering using the NAMESPACE or .First.lib() within zzz.R but that would 
> load the data every time the library is loaded.  Also considering something 
> like:
> >if (<check for R using is.R()>)
> >  data(example.data)
> > <run example>
> 
> In the example but that would create confusion for users.  

Take a look at how package MASS does this, via a promise.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595