Re: [Rd] Interface for package supplied random number generator

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Fri 01 Sep 2006 - 15:46:36 GMT

On Fri, 1 Sep 2006, Prof Brian Ripley wrote:

> This really is not a good time for us (and apparently you've know about
> this for a year). Could you come back to it once 2.4.0 is released (due
> Oct 23)?

Oops, a backspace failed: Oct 3.

>
> [We are busy with getting R-devel ready for 2.4.0, and I think that other
> mechanisms for this have been mooted, again at a time which was not
> opportune.]
>
> On Thu, 31 Aug 2006, Josef Leydold wrote:
>
> > Hi,
> >
> > As you probably know, there is a problem with the interface for adding uniform
> > random number generators in R (see by article in R News 5/2, November 2005).
> > There exists a mechanism called "user-supplied" that allows users of R
> > to run their own generator in R. However, there is no such mechanism for
> > package writers. Those who want to add their own generators abuse
> > RNGkind(kind="user-supplied") for their purpose.
> > The problem with this approach is that it relies on the unique existence of the
> > function "user_unif_rand". When two packages are loaded that use this interface,
> > then at least one package is broken. If the user herself loads a shared library
> > that contains such a function, some of the functionalities of all the
> > corresponding packages are broken.
> >
> > When writing my paper I found the following packages on CRAN that abuse this
> > interface (meanwhile there might be more packages):
> >
> > randaes_0.1.tar.gz
> > rlecuyer_0.1.tar.gz
> > rsprng_0.3-1.tar.gz
> > rstream_1.1.tar.gz
> > SuppDists_1.0-13.tar.gz
> >
> > what makes the situation even more complicated is the fact that some of these
> > packages are loaded automaticall by other packages.
> > For example, package 'rlecuyer' is loaded by
> >
> > snow_0.2-1.tar.gz
> > snowFT_0.0-1.tar.gz
> > varSelRF_0.6-2.tar.gz
> >
> > To solve this problem, Stefan Theussl and I have tried to extend the mechanism
> > for random number generators in the following way:
> >
> > - we have added a new kind of generators: "package-supplied"
> >
> > - this generator kind needs functions named 'package_unif_rand', 'package_unif_init',
> > 'package_unif_nseed', and 'package_unif_seedloc'
> > (analogously to the functions for kind "user-supplied")
> >
> > - RNGkind has an additional optional argument:
> > RNGkind <- function(kind = NULL, normal.kind = NULL, PACKAGE = "")
> > argument 'PACKAGE' is only used for the new generator kind "package-supplied"
> >
> > - similarly the function set.seed needs the optinal argument 'PACKAGE'
> >
> > Since I need such an extended interface (and I assume that other package
> > write do also) I ask whether this extension can be included into R.
> > We have implemented a first experimental version of this modified interface.
> > A patch against the development snapshot R-devel_2006-08-30.tar.gz is available.
> > However, it is a little bit too long (239 lines) to be posted here.
> >
> > Of course suggestions for an alternative approach are welcome.
> >
> > Josef
> >
> >
> >
>
>

-- 
Brian D. Ripley,                  ripley@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

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