[R] code to find all distinct subsets of size r from a set of size n

I'm doing a permutation test and need to efficiently generate all distinct subsets of size r from a set of size n. P 138 of MASS (4th ed) notes that The code to generate this efficiently is in the scripts. I was unable to find this code on quick inspection of the \library\MASS\scripts file for

Re: [R] code to find all distinct subsets of size r from a set of size n

For permutations a couple of options are 'permutations' in package gtools, and 'urnsamples' in package prob hth, Kingsford Jones On Fri, Mar 13, 2009 at 6:35 AM, Dale Steele dale.w.ste...@gmail.com wrote: I'm doing a permutation test and need to efficiently generate all distinct subsets of

Re: [R] code to find all distinct subsets of size r from a set of size n

If your subsets are to be taken from the rows of a dataframe, df, and the size is r, then something like this could satisfy: apply(combn(nrow(df), r), 2, function(x) df[x, ]) (Although these are not really permutations as I understand that term.) -- David Winsemius On Mar 13, 2009, at 8:35