[R] (Most efficient) way to make random sequences of random sequences

Liaw, Andy andy_liaw at merck.com
Tue Aug 21 23:39:05 CEST 2007


Similarly:

s <- c(replicate(N, sample(3)))

Andy 

From: roger koenker
> One way:
> 
> 	N <- 10
> 	 s <- c(apply(matrix(rep(1:3,N),3,N),2,sample))
> 
> 
> url:    www.econ.uiuc.edu/~roger            Roger Koenker
> email    rkoenker at uiuc.edu            Department of Economics
> vox:     217-333-4558                University of Illinois
> fax:       217-244-6678                Champaign, IL 61820
> 
> 
> On Aug 21, 2007, at 3:49 PM, Emmanuel Levy wrote:
> 
> > Hi,
> >
> > I was wondering the what would be the (most efficient) way 
> to generate
> > a sequence
> > of sequences, i mean:
> >
> > if I have 1,2 and 3.
> >
> > I'd like to generate a sequence of length N*3 (N ~ 
> 1,000,000 or more)
> >
> > Where random permutations of the sequence 1,2,3 follow each other.
> >
> > i.e  1,2,3,1,3,2,3,2,1
> >
> > /!\ The thing is that there should never be twice the same number of
> > in the same sub-sequence, meaning that this is different from
> > generating a vector with the numbers 1,2 and 3 randomly distributed.
> >
> > Any suggestion very welcome! Thanks,
> >
> > Emmanuel
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > 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.
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> 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.
> 
> 
> 


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