R help - Jan 2011 - how to cut a multidimensional array along a chosen dimension and store each piece into a list

Dear R-Helpers,

I wonder whether there is a function which cuts a multiple dimensional array
along a chosen dimension and then store each piece (still an array of one
dimension less) into a list.
For example,

arr <- array(seq(1*2*3*4),dim=c(1,2,3,4))  # I made a point to set the
length of the first dimension be 1to test whether I worry about drop=F
option.

brkArrIntoListAlong <- function(arr,alongWhichDim){
####
return(outlist)
}

I have tried splitter_a in plyr package but does not get what I want.

library(plyr)
plyr:::splitter_a(arr,3)

I understand that I can write a for loop to make it happen but I am
searching for a better solution.

Thanks in advance.

-Sean

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On Mon, Jan 17, 2011 at 2:20 PM, Sean Zhang <seanecon at gmail.com>
wrote:
> Dear R-Helpers,
>
> I wonder whether there is a function which cuts a multiple dimensional
array
> along a chosen dimension and then store each piece (still an array of one
> dimension less) into a list.
> For example,
>
> arr <- array(seq(1*2*3*4),dim=c(1,2,3,4)) ?# I made a point to set the
> length of the first dimension be 1to test whether I worry about drop=F
> option.
>
> brkArrIntoListAlong <- function(arr,alongWhichDim){
> ####
> return(outlist)
> }
>
> I have tried splitter_a in plyr package but does not get what I want.
>
> library(plyr)
> plyr:::splitter_a(arr,3)
We'll you're really not supposed to call internal functions - you
probably want:

alply(arr, 3)

but you don't say what is wrong with the output.

Hadley

-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/