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

Emmanuel Levy emmanuel.levy at gmail.com
Tue Aug 21 23:49:36 CEST 2007

```Thanks for all your suggestions!

I guess I'll have to make tests to see which one is faster :)

Will come back to you when it's done.

On 8/21/07, Liaw, Andy <andy_liaw at merck.com> wrote:
> 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
> > > guide.html
> > > and provide commented, minimal, self-contained, reproducible code.
> >
> > ______________________________________________
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> > and provide commented, minimal, self-contained, reproducible code.
> >
> >
> >
>
>
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