R: Dimensions of an Object

dim {base} | R Documentation

## 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).

### Details

The functions `dim` and `dim<-` are internal generic primitive functions.

`dim` has a method for `data.frame`s, which returns the lengths of the `row.names` attribute of `x` and of `x` (as the numbers of rows and columns respectively).

### 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.

### 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]

[Package base version 3.5.1 Index]