Many thanks Jim for your help. I am trying to apply the permutations with a sequence of 20 but I obtain the error message:
Error in matrix(NA, nrow = nrows, ncol = lenx) : invalid 'nrow' value (too large or NA) In addition: Warning message: In matrix(NA, nrow = nrows, ncol = lenx) : NAs introduced by coercion to integer range Here is the code: library(partitions) library(crank) r <- t(restrictedparts(10, 20)) r <- split(r, seq(nrow(r))) rp <- crank::permute(r[[sample(1:length(r), 1)]]) rp[sample(1:dim(rp)[1],1),] In this case, Is it correct to permute the elements of a vector rather than to permute a vector ? Many thanks for your time. Have a nice day Nell ________________________________ De : Jim Lemon <drjimle...@gmail.com> Envoyé : mardi 10 juillet 2018 17:44:13 À : Nelly Reduan Objet : Re: [R] Generate N random numbers with a given probability and condition Hi Nell, I may not have the right idea about this, but I think you need to do this in two steps if it can be done. Let's say you want a sequence of 20 (N) numbers between 0 and 10 that sums to 10 (M). You can enumerate the monotonically increasing sequences like this: c(0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1) c(0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,2) ... c(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,10) So if you select one of these sequences at random, there will be a further set of sequences that are permutations of it. By randomly selecting one of those permutations, I think you can solve your problem. However, this is going to be computationally intensive, with the set of permutations being very large for large N. Here is an example using N = M = 5: # enumerate the sequences = M rs5<-list(c(1,1,1,1,1),c(0,1,1,1,2),c(0,0,1,1,3),c(0,0,0,1,4), c(0,0,1,2,2),c(0,0,0,2,3),c(0,0,0,0,5)) library(crank) # generate the permutations for one sequence (120 in this case) rs5_s1<-permute(rs5[[sample(1:length(rs5),1)]]) # select one of the permutations at random rs5_s1[sample(1:dim(rs5_s1)[1],1),] [1] 4 0 1 0 0 Jim On Wed, Jul 11, 2018 at 10:11 AM, Nelly Reduan <nell.r...@hotmail.fr> wrote: > Thank you very much for your reply. > > > By omitting the probability, the expected results could be: > > > c(2, 0, 0, 0, 0, 0, 1, 0, 5, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0) > > > c(0, 0, 1, 0, 0, 1, 1, 0, 6, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0) > > > If I omit the probability, I would like to generate N random positive > integers that sum to M and the integers would be selected from a uniform > distribution. > > > Many thanks for your time > > Nell > > > ________________________________ > De : Rolf Turner <r.tur...@auckland.ac.nz> > Envoyé : mercredi 4 juillet 2018 16:11:11 > À : Nelly Reduan > Cc : r-help@r-project.org > Objet : Re: [R] Generate N random numbers with a given probability and > condition > > > On 05/07/18 10:21, Nelly Reduan wrote: > >> Dear all, >> >> I would like to generate N random numbers with a given probability and >> condition but I'm not sure how to do this. >> For example, I have N = 20 and the vector from which to choose is seq(0, 10, >> 1). I have tested: >> >> x <- sample(seq(0, 10, 1), 20, replace=TRUE, prob=rep(0.28, >> times=length(seq(0, 10, 1)))) >> >> But I don�t know how to put the condition sum(x) <= max(seq(0, 10, 1)). >> Many thanks for your time. > > Your thinking requires considerable clarification. > > (1) Note that seq(0,10,1) is just 0, 1, 2, ..., 10. > > (2) Hence length(seq(0,10,1)) is 11. > > (3) Likewise max(seq(0,10,1)) is 10. > > (4) Your prob vector is *constant* --- so specifying "prob" makes > no difference --- the result is the same as if you omitted "prob". > > (5) You need to think carefully about what you really mean by "random". > In what way do you want the final result to be "random"? > > I expect that the lecturer who assigned this problem to you needs to > clarify his/her thinking as well. > > cheers, > > Rolf Turner > > -- > Technical Editor ANZJS > Department of Statistics > University of Auckland > Phone: +64-9-373-7599 ext. 88276 > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
