generate combination multiset (set with repetition)
Dear Reuben,
On Thu, Dec 11, 2008 at 12:53 PM, baptiste auguie <ba208 at exeter.ac.uk> wrote:
Hi, Perhaps you can use expand.grid and then remove the mirror combinations,
values <- 1:3 tmp <- expand.grid(values, values) unique.combs <- tmp[tmp[, 1]<=tmp[, 2], ] unique.combs[do.call(order, unique.combs), ] # reorder if you wish Var1 Var2 1 1 1 4 1 2 7 1 3 5 2 2 8 2 3 9 3 3
I vaguely recall a discussion a few months ago on extending this approach to a variable number of arguments to expand.grid. Hope this helps, baptiste
Here is another way: library(prob) urnsamples(1:3, size = 2, ordered = FALSE, replace = TRUE) You can convert to a matrix with as.matrix(), if desired. Regards, Jay
*************************************************** G. Jay Kerns, Ph.D. Associate Professor Department of Mathematics & Statistics Youngstown State University Youngstown, OH 44555-0002 USA Office: 1035 Cushwa Hall Phone: (330) 941-3310 Office (voice mail) -3302 Department -3170 FAX E-mail: gkerns at ysu.edu http://www.cc.ysu.edu/~gjkerns/