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
--
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Josef Leydold | Vienna University of Economics and Business Administration
| Department of Statistics and Mathematics
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Augasse 2-6 | Tel. +43 1 31336 4695
A-1090 Vienna | FAX +43 1 31336 774
European Union | email [EMAIL PROTECTED]
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Alles Unglueck kam daher, dass die Denkenden nicht mehr handeln konnten,
und die Handelnden keine Zeit mehr fanden zu denken. (Marlen Haushofer)
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