[R] All permutations

[kjetil halvorsen]

As frequently in R, when something can be done it can be done in more
ways. There is also the combinat package on CRAN. Here is a comparision:

> system.time(permn(1:5))
[1]   NA   NA 0.16   NA   NA
> system.time(permutations(5,5))
[1]   NA   NA 0.17   NA   NA
> system.time(permn(1:8))
[1]    NA    NA 52.68    NA    NA
> system.time(permutations(8,8))
[1]   NA   NA 71.5   NA   NA

so the permn function from combinat seemxs to be marginally faster.

This is a slow windows 98  machine.

Kjetil Halvorsen

Juan Ramon Gonzalez wrote:
> 
> Ravi,
> 
> Look at the gregmisc package and  "permutations" function
> 
> Juan
> 
> ----- Original Message -----
> From: "David Meyer" <david.meyer at ci.tuwien.ac.at>
> To: "Ravi Varadhan" <rvaradha at jhsph.edu>
> Cc: "R-Help (E-mail)" <r-help at stat.math.ethz.ch>
> Sent: Wednesday, September 18, 2002 7:24 PM
> Subject: Re: [R] All permutations
> 
> > v <- 1:2
> > expand.grid(v,v,v)
> >
> > g.,
> > -d
> >
> > Ravi Varadhan wrote:
> > >
> > > Hi:
> > >
> > >  I would like to obtain all permutations of size n containing the k
> distinct
> > > objects. For example, for size n=3 and k=2 objects (1 and 2), I want the
> > > following 8x3 matrix:
> > >
> > >  1 1 1
> > >  1 1 2
> > >  1 2 1
> > >  2 1 1
> > >  1 2 2
> > >  2 2 1
> > >  2 1 2
> > >  2 2 2
> > >
> > >  Is there any R function to accomplish this?
> > >
> > >  Thanks for the help,
> > >  Ravi.
> > >
> >
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