I've had a need for multinomial "random number generation"
occasionally. And other people too.
The following code is currently in the
(very small ``not very high importance'') CRAN package normix
--- which I will rename to "nor1mix" very seen because of a
``name registration'' problem
I want to add "this" (well the functionality) to a standard
package -- "mva" probably.
The reason for my post is to ask about importance for C code
(and a an official API to that).
1) I think we have no clear precedence of a C interface to
**multivariate** random numbers, and
2) It might be of too marginal importance.
If you (discussants) conclude that a C interface is not at all
desired, I consider using the R code as it is now -- which is
not optimal --- and most importantly:
If this should ever be changed, the change would hardly be
back-compatible.
In other words, calling the not-yet existing C interface would
produce different random numbers...
----
- Opinions ?
- Is there already C code around to do this ``in one step'' ?
Martin Maechler <[EMAIL PROTECTED]> http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum LEO C16 Leonhardstr. 27
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-1-632-3408 fax: ...-1228 <><
## This is based on rmultz2() from S-news by Alan Zaslavsky & Scott Chasalow;
## in R available from library(combinat) -- but it has
## Arg.names like rbinom(); returns n x p matrix
rmultinom <- function(n, size, prob) {
K <- length(prob) # #{classes}
matrix(tabulate(sample(K, n * size, repl = TRUE, prob) + K * 0:(n - 1),
nbins = n * K),
nrow = n, ncol = K, byrow = TRUE)
}
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