As Erich points out, there is some question as to what the original problem really is but lets assume its as Erich describes. Then, to get a random ordered permutation we just get a random permutation of 12 elements and sort the intra-block elements like this:
c(apply(matrix(sample(12,12),3),2,sort)) Note that there are 12! = 479,001,600 permutations of 12 elements and 3!^4 = 1,296 of those permutations correspond to each ordered permutation so there are 479,001,600 / 1,296 = 369,600 ordered permutations in all. Erich Neuwirth <erich.neuwirth <at> univie.ac.at> writes: : : Perhaps what you want might better be described as : ordered partitions? : : Is what you want the following: : : We study sequences of length 12 and divide them in : 4 segments : position 1 2 3, position 4 5 6, : position 7 8 9, position 10 11 12, : : Find all permutation sequences of the numbers 1 to 12 : with the property that all segment sequences : are monotonically increasing. : : I think that produces what you need. : Since the segments are ordered, you avoid intra-block permutations. : : If that is what you want, writing a recursive function should not be : too hard. : : Jordi Altirriba GutiÃrrez wrote: : : > Dear R users, : > Iâm a beginner user of R and Iâve a problem with permutations that I : > donât know how to solve. Iâve 12 elements in blocks of 3 elements and I : > want only to make permutations inter-blocks (no intra-blocks) (sorry if : > the terminology is not accurate), something similar to: : > : > 1 2 3 | 4 5 6 | 7 8 9 | 10 11 12 ----------1st permutation : > : > 1 3 2 | 4 5 6 | 7 8 9 | 10 11 12 NO : > - - : > 3 2 1 | 4 5 6 | 7 8 9 | 10 11 12 NO : > - - - : > 1 2 4 | 3 5 6 | 7 8 9 | 10 11 12 YES-----2nd permutation : > - - : > 4 5 6 | 1 2 3 | 7 8 9 | 10 11 12 YES-----3rd permutation : > - - - - - - : > 4 5 6 | 2 1 3 | 7 8 9 | 10 11 12 NO : > - - : > .... : > : > Thanks for your time, : > : > Jordi Altirriba : > Ph D student : > : > Hospital Clinic â Barcelona - Spain : > : > : > MSN Motor. http://motor.msn.es/researchcentre/ : > : > ______________________________________________ : > R-help <at> 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 : > : ______________________________________________ [EMAIL PROTECTED] 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