[R] Combinatorial problem
David Scott
d.scott at auckland.ac.nz
Wed Aug 12 23:27:19 CEST 2009
Bernd Bischl wrote:
> Dimitris Rizopoulos wrote:
>> you could try something like the following:
>>
>> groups <- list(gp1 = 1:3, gp2 = 4:5, gp3 = 6:7,
>> gp4 = 8:10, gp5 = 11)
>>
>> combn(5, 2, function (x) expand.grid(groups[x]), simplify = FALSE)
>> combn(5, 3, function (x) expand.grid(groups[x]), simplify = FALSE)
>> combn(5, 4, function (x) expand.grid(groups[x]), simplify = FALSE)
>>
> and this transforms it nicely into a single matrix
>
> y <- combn(5, 2, function (x) as.matrix(expand.grid(groups[x])),
> simplify = FALSE)
> Reduce(rbind, y)
>
>
> Bernd
>
This is absolutely, totally awesome guys. Thanks very much.
For the benefit of other readers, here is what happened.
I spent 10 minutes composing a question (tried to make it easy to set
up). Went off and did some other emailing, decided to check R-help and
there were two replies answering my question perfectly.
Thanks again
David Scott
_________________________________________________________________
David Scott Department of Statistics
The University of Auckland, PB 92019
Auckland 1142, NEW ZEALAND
Phone: +64 9 923 5055, or +64 9 373 7599 ext 85055
Email: d.scott at auckland.ac.nz, Fax: +64 9 373 7018
Director of Consulting, Department of Statistics
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