array {base}

R Documentation

Multi-way Arrays

Description

Creates or tests for arrays.

Usage

array(data = NA, dim = length(data), dimnames = NULL)
as.array(x, ...)
is.array(x)

Arguments

data	a vector (including a list) giving data to fill the array.
dim	the dim attribute for the array to be created, that is a vector of length one or more giving the maximal indices in each dimension.
dimnames	either NULL or the names for the dimensions. This is a list with one component for each dimension, either NULL or a character vector of the length given by dim for that dimension. The list can be named, and the list names will be used as names for the dimensions. If the list is shorter than the number of dimensions, it is extended by NULLs to the length required
x	an R object.
...	additional arguments to be passed to or from methods.

Value

array returns an array with the extents specified in dim and naming information in dimnames. The values in data are taken to be those in the array with the leftmost subscript moving fastest. If there are too few elements in data to fill the array, then the elements in data are recycled. If data has length zero, NA of an appropriate type is used for atomic vectors (0 for raw vectors) and NULL for lists.

as.array is a generic function for coercing to arrays. The default method does so by attaching a dim attribute to it. It also attaches dimnames if x has names. The sole purpose of this is to make it possible to access the dim[names] attribute at a later time.

is.array returns TRUE or FALSE depending on whether its argument is an array (i.e., has a dim attribute of positive length) or not. It is generic: you can write methods to handle specific classes of objects, see InternalMethods.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

aperm, matrix, dim, dimnames.

Examples

dim(as.array(letters))
array(1:3, c(2,4)) # recycle 1:3 "2 2/3 times"
#     [,1] [,2] [,3] [,4]
#[1,]    1    3    2    1
#[2,]    2    1    3    2

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