| asplit {base} | R Documentation |
Split an array or matrix by its margins.
asplit(x, MARGIN)
x |
an array, including a matrix. |
MARGIN |
a vector giving the margins to split by.
E.g., for a matrix |
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.
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.
## 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))