# [R] Sorting rows in a matrix based on vector of indecies

Esmail Bonakdarian esmail.js at gmail.com
Sat Feb 21 00:55:09 CET 2009

```Hi David,

This was useful, thanks.

The example was just that, there are no "a"s, "b",s etc I was
just trying to show what I was trying to do.

Using m[v,]

where m was the matrix in my example and v the vector of
index values works great as you suggested Thanks.

R is quite a powerful language as I am starting to discover
(and folks on the list here are very helpful).

Regards,

Esmail

David Winsemius wrote:

> See if this helps:
>
>  > mtx<-matrix( rep(letters[1:4], 6), nrow=4)
>  > mtx
>      [,1] [,2] [,3] [,4] [,5] [,6]
> [1,] "a"  "a"  "a"  "a"  "a"  "a"
> [2,] "b"  "b"  "b"  "b"  "b"  "b"
> [3,] "c"  "c"  "c"  "c"  "c"  "c"
> [4,] "d"  "d"  "d"  "d"  "d"  "d"
>
>  > mtx[c(2, 4, 1, 3), ]
>
>      [,1] [,2] [,3] [,4] [,5] [,6]
> [1,] "b"  "b"  "b"  "b"  "b"  "b"
> [2,] "d"  "d"  "d"  "d"  "d"  "d"
> [3,] "a"  "a"  "a"  "a"  "a"  "a"
> [4,] "c"  "c"  "c"  "c"  "c"  "c"
>
> You can do with that result whatever you want:
>
> assign it,   m2 <- mtx[c(2, 4, 1, 3), ]

```