[R] rearrange data columns

[Peter Dalgaard]

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? 
>  
>   
Here's one way:

> a <- matrix(1:6, 2, byrow=T)
> b <- -a
> ab <- rbind(a,b); dim(ab)=c(2,6)
> ab
     [,1] [,2] [,3] [,4] [,5] [,6]
[1,]    1   -1    2   -2    3   -3
[2,]    4   -4    5   -5    6   -6

Here's another:

> ab <- matrix(,2,6)
> ab[,seq(1,,2,3)] <- a
> ab[,seq(2,,2,3)] <- b
> ab
     [,1] [,2] [,3] [,4] [,5] [,6]
[1,]    1   -1    2   -2    3   -3
[2,]    4   -4    5   -5    6   -6



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   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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