R help - Nov 2011 - permutation within rows of a matrix

Hello
This is probably a basic question but I am quite new to R. 

I need to permute elements within rows of a binary matrix, such as

     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    0    0    0    0    1    0    0    0    0     0
 [2,]    0    0    1    1    0    0    0    1    1     0
 [3,]    0    1    0    0    0    0    1    0    0     0
 [4,]    0    0    0    0    0    0    1    1    0     0
 [5,]    0    0    0    1    0    0    0    0    1     0
 [6,]    0    0    1    1    0    0    0    0    0     1
 [7,]    0    0    0    0    0    0    0    0    0     0
 [8,]    1    1    0    1    0    0    0    1    0     1
 [9,]    1    0    0    1    0    1    0    1    0     0
[10,]    0    0    0    0    0    0    0    1    0     1


That is, elements within each row are permuted freely and independently from
the other rows. 

I see that is is workable by creating a array for each row, performing
sample and binding the arrays again, but I wonder whether there is a more
efficient way of doing the trick.

Any help will be much appreciated.



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Suppose your matrix is called X.

? sample
X[sample(nrow(X)),]

Michael

On Wed, Nov 16, 2011 at 11:45 AM, Juan Antonio Balbuena <balbuena at
uv.es> wrote:
> Hello
> This is probably a basic question but I am quite new to R.
>
> I need to permute elements within rows of a binary matrix, such as
>
> ? ? [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
> ?[1,] ? ?0 ? ?0 ? ?0 ? ?0 ? ?1 ? ?0 ? ?0 ? ?0 ? ?0 ? ? 0
> ?[2,] ? ?0 ? ?0 ? ?1 ? ?1 ? ?0 ? ?0 ? ?0 ? ?1 ? ?1 ? ? 0
> ?[3,] ? ?0 ? ?1 ? ?0 ? ?0 ? ?0 ? ?0 ? ?1 ? ?0 ? ?0 ? ? 0
> ?[4,] ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?1 ? ?1 ? ?0 ? ? 0
> ?[5,] ? ?0 ? ?0 ? ?0 ? ?1 ? ?0 ? ?0 ? ?0 ? ?0 ? ?1 ? ? 0
> ?[6,] ? ?0 ? ?0 ? ?1 ? ?1 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ? 1
> ?[7,] ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ? 0
> ?[8,] ? ?1 ? ?1 ? ?0 ? ?1 ? ?0 ? ?0 ? ?0 ? ?1 ? ?0 ? ? 1
> ?[9,] ? ?1 ? ?0 ? ?0 ? ?1 ? ?0 ? ?1 ? ?0 ? ?1 ? ?0 ? ? 0
> [10,] ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?0 ? ?1 ? ?0 ? ? 1
>
>
> That is, elements within each row are permuted freely and independently
from
> the other rows.
>
> I see that is is workable by creating a array for each row, performing
> sample and binding the arrays again, but I wonder whether there is a more
> efficient way of doing the trick.
>
> Any help will be much appreciated.
>
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/permutation-within-rows-of-a-matrix-tp4076989p4076989.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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> PLEASE do read the posting guide
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>