# [R] rearrange data columns

(Ted Harding) Ted.Harding at manchester.ac.uk
Thu Oct 11 14:46:10 CEST 2007

```On 11-Oct-07 12:09:19, Robin Hankin wrote:
>
> On 11 Oct 2007, at 12:55, Martin Ivanov wrote:
>
>> Dear R users,
>>  I need to to the the following. Let a= 1 2 3
>>                                         4 5 6
>>  and b= -1 -2 -3  be (2x3) matrices.
>>         -4 -5 -6
>>  I need to combine the two matrices into a new (2x6) matrix like this:
>>
>>  ab = ( 1 -1 2 -2 3 -3 )
>>         4 -4 5 -5 6 -6
>>
>>  How can this be done in R?
>
>  > a
>       [,1] [,2] [,3]
> [1,]    1    2    3
> [2,]    4    5    6
>  > b
>       [,1] [,2] [,3]
> [1,]   -1   -2   -3
> [2,]   -4   -5   -6
>
>  > x <- cbind(a,b)+NA
>  > x
>       [,1] [,2] [,3] [,4] [,5] [,6]
> [1,]   NA   NA   NA   NA   NA   NA
> [2,]   NA   NA   NA   NA   NA   NA
>  > x[,seq(from=1,by=2,len=3)] <- a
>  > x[,seq(from=2,by=2,len=3)] <- b
>  > x
>       [,1] [,2] [,3] [,4] [,5] [,6]
> [1,]    1   -1    2   -2    3   -3
> [2,]    4   -4    5   -5    6   -6
>  >
>
>
> HTH
>
> rksh

What's wrong with

a
##     [,1] [,2] [,3]
##[1,]    1    2    3
##[2,]    4    5    6

b
##     [,1] [,2] [,3]
##[1,]   -1   -2   -3
##[2,]   -4   -5   -6

cbind(a,b)[,c(1,4,2,5,3,6)]
##     [,1] [,2] [,3] [,4] [,5] [,6]
##[1,]    1   -1    2   -2    3   -3
##[2,]    4   -4    5   -5    6   -6

??

Of course, for a more general case, you'd need a method for
generating the appropriate version of c(1,4,2,5,3,6) -- e.g.
something like Robin's "seq".

Best wishes,
Ted.

--------------------------------------------------------------------
E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 11-Oct-07                                       Time: 13:46:06
------------------------------ XFMail ------------------------------

```