# dim

0th

Percentile

##### Dimensions of an Object

Retrieve or set the dimension of an object.

Keywords
array
##### 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.frames, 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.

ncol, nrow and dimnames.

##### Aliases
• dim
• dim.data.frame
• dim<-
##### Examples
library(base) 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] 
Documentation reproduced from package base, version 3.3, License: Part of R @VERSION@

### Community examples

richie@datacamp.com at Jan 17, 2017 base v3.3.2

For matrices, dim() returns the number of rows and columns as an integer vector. {r} m <- matrix(1:12, 3, 4) dim(m) # 3 4  The same is true for data frames. {r} d <- data.frame(a = 1:3, b = 4:6, c = 7:9, d = 10:12) dim(d) # 3 4  For arrays, dim() can be longer than 2 values. {r} a <- array(1:24, dim = 2:4) dim(a) # 2 3 4  Vectors don't have a dimension attribute; dim() will always return NULL. {r} v <- 1:12 dim(v) # NULL