[R] Odp: Matrix

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 02.02.2009 16:52:06:

> 
> Hi,
> 
> I have a very basic question on merging two matrices by alternating the
> rows. For illustration, assume two matrices -
> 
> A looks like:
> 
> 10 10
> 10 10
> 
> B looks like:
> 
> 20 20
> 20 20 
> 
> How do I combine them such that I get alternating rows from A and B? My
> final result should be C which looks like:
> 
> 10 10 
> 20 20
> 10 10
> 20 20

I would rbind both matrices and then indexed the resulting matrix.

x<-rep(10,4)
y<-rep(20,4)
dim(x)<-c(2,2)
dim(y)<-c(2,2)
z<-rbind(x,y)
> z
     [,1] [,2]
[1,]   10   10
[2,]   10   10
[3,]   20   20
[4,]   20   20

ind<-c(seq(1,4,2), seq(2,4,2))
z[ind,]
 
> z[ind,]
     [,1] [,2]
[1,]   10   10
[2,]   20   20
[3,]   10   10
[4,]   20   20

Regards
Petr


> 
> Thanks very much, and I am sorry for such a newbie question.
> 
> Shruthi
> -- 
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