how to subsample all possible combinations of n species taken 1:n at a time?
If you want 128 combinations, then generate 8 16-bit random numbers and concatenate them together. You will have to check for dups as you generate the sequence, but it is at least a start and should fit within the memory of the system. On Mon, Apr 6, 2009 at 7:39 PM, David Katz
<david at davidkatzconsulting.com> wrote:
This is very cool indeed until you want to use more than 32 or so terms and most operating systems force you to go to floating point.
x=sample(2^34,1000)
Error in sample(2^34, 1000) : invalid 'x' argument In addition: Warning message: In sample(2^34, 1000) : NAs introduced by coercion jholtman wrote:
Are you just trying to obtain a combination from 25 possible terms? If so, then just sample the number you want and convert the number to binary:
sample(33554432,100)
? [1] ?6911360 ?5924262 23052661 12888381 25831589 16700013 24079278 33282839 12751862 26086726 31363494 ?7118320 21866536 ?4212929
David Katz www.davidkatzconsulting.com -- View this message in context: http://www.nabble.com/how-to-subsample-all-possible-combinations-of-n-species-taken-1%3An-at-a-time--tp22911399p22919597.html Sent from the R help mailing list archive at Nabble.com.
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Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?