# [R] permutation within rows of a matrix

R. Michael Weylandt michael.weylandt at gmail.com
Wed Nov 16 20:29:08 CET 2011

```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
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>
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