From: Robin Hankin <rksh_at_soc.soton.ac.uk>

Date: Wed 14 Jul 2004 - 18:11:48 EST

[2,] 2 11 42 82

[3,] 3 12 43 83

R> jj <- t(apply(x,1,sample))

R> jj

R> as.vector(jj)

R>

Date: Wed 14 Jul 2004 - 18:11:48 EST

Jordi

try this

R> x <- c(1,2,3, 10,11,12, 41,42,43, 81,82,83) R> dim(x) <- c(3,4) R> x [,1] [,2] [,3] [,4] [1,] 1 10 41 81

[2,] 2 11 42 82

[3,] 3 12 43 83

R> jj <- t(apply(x,1,sample))

R> jj

[,1] [,2] [,3] [,4]

[1,] 1 41 10 81 [2,] 2 11 82 42 [3,] 12 3 43 83

R> as.vector(jj)

R>

[1] 1 2 12 41 11 3 10 82 43 81 42 83

and I think that does what you want...

We take the vector, rearrange it into a matrix with three rows, then
sample *within* the rows,

then rearrange into a vector again.

There will be one forbidden permutation, namely the identity (which
may or may not be

desirable).

This method doesn't allow "intra block" permutations.

> Dear R users,

*> First of all, thanks for the incredibly fast answers and help of
**>Rolf, Marc and Robert.
**> Yes, I noticed that it was a lot of permutacions, but my intention
**>was to make this process automatic and take only 5.000 - 10.000
**>permutations. Therefore, I wanted only to take that "interesting
**>permutations" with "some information" [inter-block permutations].
**> The reason why I'm interested in these permutations is because I'm
**>using some packages of Bioconductor to analyse my data from some
**>microarrays and I thought that perhaps could be interesting to see
**>what happens when I permute my data and I compare it against the not
**>permuted data.
**> Thanks again for your time and suggestions.
**>
**>Jordi Altirriba
**>Ph. D. Student
**>
**>Hospital Clinic-Barcelona-Spain
**>
**>______________________________________________
**>R-help@stat.math.ethz.ch mailing list
**>https://www.stat.math.ethz.ch/mailman/listinfo/r-help
**>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
*

-- Robin Hankin Uncertainty Analyst Southampton Oceanography Centre SO14 3ZH tel +44(0)23-8059-7743 initialDOTsurname@soc.soton.ac.uk (edit in obvious way; spam precaution) ______________________________________________ R-help@stat.math.ethz.ch mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.htmlReceived on Wed Jul 14 18:28:18 2004

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