# [R] Combine matrix

Moshe Olshansky m_olshansky at yahoo.com
Fri Aug 17 04:00:49 CEST 2007

```This does not work in the general case. To see this,
try:
rownames(a}[5] <- "a"
and see what happens then.

--- François Pinard <pinard at iro.umontreal.ca> wrote:

> [Gianni Burgin]
> >let say something like this
>
> >>a=matrix(1:25, nrow=5)
>
> >>rownames(a)=letters[1:5]
> >> colnames(a)=rep("A", 5)
>
> >> a
> >  A  A  A  A  A
> >a 1  6 11 16 21
> >b 2  7 12 17 22
> >c 3  8 13 18 23
> >d 4  9 14 19 24
> >e 5 10 15 20 25
>
> >> b=matrix(1:40, nrow=8)
> >> rownames(b)=c(rep("a",4),rep("b",4))
> >> colnames(b)=rep("B", 5)
>
> >> b
> >  B  B  B  B  B
> >a 1  9 17 25 33
> >a 2 10 18 26 34
> >a 3 11 19 27 35
> >a 4 12 20 28 36
> >b 5 13 21 29 37
> >b 6 14 22 30 38
> >b 7 15 23 31 39
> >b 8 16 24 32 40
>
> >as a results I wold like something like
>
> >  A  A  A  A  A  B  B  B  B  B
> >a 1  6 11 16 21  1  9 17 25 33
> >a 1  6 11 16 21  2 10 18 26 34
> >a 1  6 11 16 21  3 11 19 27 35
> >a 1  6 11 16 21  4 12 20 28 36
> >b 2  7 12 17 22  5 13 21 29 37
> >b 2  7 12 17 22  6 14 22 30 38
> >b 2  7 12 17 22  7 15 23 31 39
> >b 2  7 12 17 22  8 16 24 32 40
>
> >does it is clear? is there a function that automate
> this operation?
>
> Like, maybe:
>
>    cbind(a[rownames(b),], b)
>
>
>
> --
> François Pinard   http://pinard.progiciels-bpi.ca
>
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