R help - Oct 2005 - Generalised rbind/cbind

Dear list,

Is there a generalised form of rbind/cbind for combining
matrices/arrays into higher-D structures?  ie. if I have:

a <- matrix(2,2,2)
b <- matrix(3,2,2)

how can I get

array(rep(c(3,2), each=4), c(2,2,2))

?

It seems like this would be the job of a generalised abind function:
abind(a,b, along=1) == rbind(a,b)
abind(a,b, along=2) == cbind(a,b)
abind(a,b, along=3) ==array(rep(c(3,2), each=4), c(2,2,2))

Thanks,

Hadley

On Fri, 2005-10-21 at 17:42 -0500, hadley wickham wrote:
> Dear list,
> 
> Is there a generalised form of rbind/cbind for combining
> matrices/arrays into higher-D structures?  ie. if I have:
> 
> a <- matrix(2,2,2)
> b <- matrix(3,2,2)
> 
> how can I get
> 
> array(rep(c(3,2), each=4), c(2,2,2))
> 
> ?
> 
> It seems like this would be the job of a generalised abind function:
> abind(a,b, along=1) == rbind(a,b)
> abind(a,b, along=2) == cbind(a,b)
> abind(a,b, along=3) ==array(rep(c(3,2), each=4), c(2,2,2))
> 
> Thanks,
> 
> Hadley
Hadley,

You just described the abind() function in the 'abind' package by Tony
Plate and Richard Heiberger.

HTH,

Marc Schwartz