[BioC] how split a matrix

[Martin Morgan]

On 02/24/2012 05:27 AM, Ali Mohammadian wrote:
> Hi Sirs,
>
> I have a matrix, and I have written  a function to split it by its
> columns, the algorithm works manually, but does not work in R:
>
> A= matrix (rnorm (96),8,12)
> get.replicates = function (A, reps=reps){
> 	temp = array(-999,dim=c(dim (A) [2]/reps,dim(A) [1],reps))
> 	for (replicates.no in 1: (dim (A) [2]/reps)) {
> 	temp [replicates.no, , ] = A [ , reps*(replicates.no-1)+1:
> reps*(replicates.no) ]

Maybe you mean

   reps * (replicates.no - 1) + seq_len(reps)

? (seq_len(reps) is safer than 1:reps, e.g., when reps=0). If so then

   dim(A) = c(nrow(A), reps, ncol(A) / reps)

creates an array; if the first index of the updated A must be the 
replicate, then follow this with aperm(A, c(3, 1, 2)).

Martin

> 	}
> temp	
> }
>
> get.replicates (A,3)
>
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