[R] permutations from vectors out of a matrix

[Meyners, Michael, LAUSANNE, AppliedMathematics]

Sorry, wrong button. Below a hopefully more helpful solution...

Etienne,
I don't see the point in avoiding some 'special' packages. If you are
willing to change your mind in this regard, try one of the following
solutions that work for me:

library(combinat)
apply(mat, 2, function(x) unique(permn(x)))

# each object in the list contains the permutations from once column of
mat:
apply(mat, 2, function(x) do.call(rbind, unique(permn(x))))		

# all vectors you wanted in one matrix; note that they are in the rows,
so you might want to transpose this:
do.call(rbind, apply(mat, 2, function(x) do.call(rbind,
unique(permn(x)))))	

Not sure about the size of your original problem, though, it might take
a while. If you still want to avoid the (small!) package, you might
consider copying the code for permn from combinat to define the function
within your file. I guess it works (but didn't check) as it does not
seem to require any of the other functions of the package.

HTH, Michael


> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Etienne Stockhausen
> Sent: Montag, 18. Januar 2010 19:20
> To: r-help at r-project.org
> Subject: [R] permutations from vectors out of a matrix
> 
> Dear R-Users,
> I'm relativley new to R and have the following problem. I 
> need all permutations of the vectors created by the collumns 
> of a matrix. I will give a small example:
>    
>     p=3
>     
> n=2^p-1                                                       
>                   
> #number of obtainable vectors
>     mat=matrix(0,p,p)
>     for(i in 1:p)
>      {
>        mat[i:1,i]=1/i
>      }
> 
> mat is now a quadratic matrix and n is the number of the 
> vectors I try to get when I compute all permutations of the 
> vectors built by the individual columns. It should work for 
> all quadratic matrix and I want to avoid using some 'special' 
> packages.
> In the example I need the following vectors at the end:
> (1,0,0); (0,1,0); (0,0,1); (0.5,0.5,0); (0.5,0,0.5); 
> (0,0.5,0.5); (1/3,1/3,1/3).
> I hope my intention becomes clear.
> 
> I'm looking foward to any ideas and clues that might help me.
> Thanks in advance and best regards.
> 
> Etienne
> 
> ______________________________________________
> R-help at r-project.org 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.
>