aperm
Array Transposition
Transpose an array by permuting its dimensions and optionally resizing it.
- Keywords
- array
Usage
aperm(a, perm, …)
# S3 method for default
aperm(a, perm = NULL, resize = TRUE, …)
# S3 method for table
aperm(a, perm = NULL, resize = TRUE, keep.class = TRUE, …)
Arguments
- a
the array to be transposed.
- perm
the subscript permutation vector, usually a permutation of the integers
1:n
, wheren
is the number of dimensions ofa
. Whena
has named dimnames, it can be a character vector of lengthn
giving a permutation of those names. The default (used wheneverperm
has zero length) is to reverse the order of the dimensions.- resize
a flag indicating whether the vector should be resized as well as having its elements reordered (default
TRUE
).- keep.class
logical indicating if the result should be of the same class as
a
.- …
potential further arguments of methods.
Value
A transposed version of array a
, with subscripts permuted as
indicated by the array perm
. If resize
is TRUE
,
the array is reshaped as well as having its elements permuted, the
dimnames
are also permuted; if resize = FALSE
then the
returned object has the same dimensions as a
, and the dimnames
are dropped. In each case other attributes are copied from a
.
The function t
provides a faster and more convenient way of
transposing matrices.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
See Also
t
, to transpose matrices.
Examples
library(base)
# NOT RUN {
# interchange the first two subscripts on a 3-way array x
x <- array(1:24, 2:4)
xt <- aperm(x, c(2,1,3))
stopifnot(t(xt[,,2]) == x[,,2],
t(xt[,,3]) == x[,,3],
t(xt[,,4]) == x[,,4])
UCB <- aperm(UCBAdmissions, c(2,1,3))
UCB[1,,]
summary(UCB) # UCB is still a contingency table
# }