Not sure why the columns are all headed "i"! The use of rbind and
cbind
makes this horribly memory-intensive, so much so that the practical
limit on my system was n=9. Of course, beyond n=10 you would have trouble
storing the answer in a single matrix. But, do try to avoid repeated
rbind-ing like this as it means the vector of matrix entries has to
be re-mapped every time. Grow it in blocks (i rows at a tiem, here).
On Sun, 17 Dec 2000, Trenkler, Dietrich wrote:
> Niels Waller wrote:
>
> > Does anyone know of an R (or S-PLUS) function for delineating all
possible
> > combinations and permutations?
>
> The following function delivers all permutations of 1:n.
>
> all.perm <- function(n) {
> p <- matrix(1, ncol = 1)
> for (i in 2:n) {
> p <- pp <- cbind(p, i)
> v <- c(1:i, 1:(i - 1))
> for (j in 2:i) {
> v <- v[-1]
> p <- rbind(p, pp[, v[1:i]])
> }
> }
> p
> }
>
>
>
> Regards,
>
> *** D.Trenkler ***
>
> ===================================================================>
Dietrich Trenkler (trenkler at nts6.oec.uni-osnabrueck.de)
> Statistik / Empirische Wirtschaftsforschung
> Universitaet Osnabrueck
> Rolandstrasse 8 Phone: +49(0) 541-969-2753
> D-49069 Osnabrueck Fax : +49(0) 541-969-2745
> GERMANY
> ===================================================================>
> >
>
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
> r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
> Send "info", "help", or "[un]subscribe"
> (in the "body", not the subject !) To: r-help-request at
stat.math.ethz.ch
>
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
>
--
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 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !) To: r-help-request at
stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._