adrop

From abind v1.4-5 by Tony Plate

Drop dimensions of an array object

Drop degenerate dimensions of an array object. Offers less automaticity and more control than the base drop() function. adrop() is a S3 generic, with one method, adrop.default, supplied in the abind package.

Keywords: array , manip

Usage

adrop(x, drop = TRUE, named.vector = TRUE, one.d.array = FALSE, ...)

Arguments

x: An array (including a matrix)
drop: A logical or numeric vector describing exactly which dimensions to drop. It is intended that this argument be supplied always. The default is very rarely useful (drop=TRUE means drop the first dimension of a 1-d array).
named.vector: Optional, defaults to TRUE. Controls whether a vector result has names derived from the dimnames of x.
one.d.array: Optional, defaults to FALSE. If TRUE, a one-dimensional array result will be an object with a dim attribute of length 1, and possibly a dimnames attribute. If FALSE, a one-dimensional result will be a vector object (named if named.vector==TRUE).
...: There are no additional arguments allowed for adrop.default but other methods may use them.

Details

Dimensions can only be dropped if their extent is one, i.e., dimension i of array x can be dropped only if dim(x)[i]==1. It is an error to request adrop to drop a dimension whose extent is not 1.

A 1-d array can be converted to a named vector by supplying drop=NULL (which means drop no dimensions, and return a 1-d array result as a named vector).

Value

If x is an object with a dim attribute (e.g., a matrix or array), then adrop returns an object like x, but with the requested extents of length one removed. Any accompanying dimnames attribute is adjusted and returned with x.

Examples

x <- array(1:24,dim=c(2,3,4),dimnames=list(letters[1:2],LETTERS[1:3],letters[23:26]))
adrop(x[1,,,drop=FALSE],drop=1)
adrop(x[,1,,drop=FALSE],drop=2)
adrop(x[,,1,drop=FALSE],drop=3)
adrop(x[1,1,1,drop=FALSE],drop=1)
adrop(x[1,1,1,drop=FALSE],drop=2)
adrop(x[1,1,1,drop=FALSE],drop=3)
adrop(x[1,1,1,drop=FALSE],drop=1:2)
adrop(x[1,1,1,drop=FALSE],drop=1:2,one.d=TRUE)
adrop(x[1,1,1,drop=FALSE],drop=1:2,named=FALSE)
dim(adrop(x[1,1,1,drop=FALSE],drop=1:2,one.d=TRUE))
dimnames(adrop(x[1,1,1,drop=FALSE],drop=1:2,one.d=TRUE))
names(adrop(x[1,1,1,drop=FALSE],drop=1:2,one.d=TRUE))
dim(adrop(x[1,1,1,drop=FALSE],drop=1:2))
dimnames(adrop(x[1,1,1,drop=FALSE],drop=1:2))
names(adrop(x[1,1,1,drop=FALSE],drop=1:2))

Documentation reproduced from package abind, version 1.4-5, License: LGPL (>= 2)

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