base (version 3.3.3)

dim: Dimensions of an Object

Description

Retrieve or set the dimension of an object.

Usage

dim(x)
dim(x) <- value

Arguments

x

an R object, for example a matrix, array or data frame.

value

For the default method, either NULL or a numeric vector, which is coerced to integer (by truncation).

Value

For an array (and hence in particular, for a matrix) dim retrieves the dim attribute of the object. It is NULL or a vector of mode integer. The replacement method changes the "dim" attribute (provided the new value is compatible) and removes any "dimnames" and "names" attributes.

Details

The functions dim and dim<- are internal generic primitive functions. dim has a method for data.frames, which returns the lengths of the row.names attribute of x and of x (as the numbers of rows and columns respectively).

References

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

See Also

ncol, nrow and dimnames.

Examples

x <- 1:12 ; dim(x) <- c(3,4)
x

# simple versions of nrow and ncol could be defined as follows
nrow0 <- function(x) dim(x)[1]
ncol0 <- function(x) dim(x)[2]