# asplit: Split Array/Matrix By Its Margins

Description Usage Arguments Details Value Examples

## Description

Split an array or matrix by its margins.

## Usage

 `1` ```asplit(x, MARGIN) ```

## Arguments

 `x` an array, including a matrix. `MARGIN` a vector giving the margins to split by. E.g., for a matrix `1` indicates rows, `2` indicates columns, `c(1, 2)` indicates rows and columns. Where `x` has named dimnames, it can be a character vector selecting dimension names.

## Details

The values of the splits can also be obtained (less efficiently) by `split(x, slice.index(x, MARGIN))`.

`apply` always simplifies common length results, so attempting to split via `apply(x, MARGIN, identity)` does not work (as it simply gives `x`). By chaining `asplit` with `lapply` or `vapply`, one can obtain variants of `apply` which do not auto-simplify.

## Value

A “list array” with dimension dv and each element an array of dimension de and dimnames preserved as available, where dv and de are, respectively, the dimensions of `x` included and not included in `MARGIN`.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20``` ```## A 3-dimensional array of dimension 2 x 3 x 4: d <- 2 : 4 x <- array(seq_len(prod(d)), d) x ## Splitting by margin 2 gives a 1-d list array of length 3 ## consisting of 2 x 4 arrays: asplit(x, 2) ## Spltting by margins 1 and 2 gives a 2 x 3 list array ## consisting of 1-d arrays of length 4:a asplit(x, c(1, 2)) ## Compare to split(x, slice.index(x, c(1, 2))) ## A 2 x 3 matrix: (x <- matrix(1 : 6, 2, 3)) ## To split x by its rows, one can use asplit(x, 1) ## or less efficiently split(x, slice.index(x, 1)) split(x, row(x)) ```