dim
Dim Attribute of an Object

### Description

Returns or changes the dim attribute, which describes the dimensions of a matrix, a data frame, or an array.

### Usage

    dim(x)
    dim(x) <- value

### Arguments

x | any object.
value | must be a vector of integers (or anything that can be coerced to a vecter of integers). The product of value should be equal to the length of x. Missing values or negative integers are not allowed. If NULL, the dim attribute is removed.

### Details

This is a generic function. dim has a method for data frames that counts the length of the row.names attribute and the number of columns. You cannot change the dimensions of a data frame.
Arrays and matrices have a dim attribute that is an integer vector, with the property that prod(dim(x))==length(x). This attribute identifies an object as an array.
Value

dim(x) | returns an integer vector of the dimensions of x, if any. It returns NULL if x does not have dimensions.
dim(x) <- value | returns value.

Side Effects
Adding or removing the "dim" attribute typically affects the class of x.
Assigning dim to a vector, a matrix, or an array removes the names and dimnames attributes. (No re-ordering of the elements of x is implied.)
See Also
dimnames, ncol, array, matrix, data.frame, length.
Examples

    x <- matrix(1:12, nrow = 3)
    dim(x)  #   c(3, 4)
    length(dim(x)) # 2
    x
    #      [,1] [,2] [,3] [,4]
    # [1,]    1    4    7   10
    # [2,]    2    5    8   11
    # [3,]    3    6    9   12
    dim(x) <- c(2, 6)
    class(x)  #  matrix
    x
    #         [,1] [,2] [,3] [,4] [,5] [,6]
    #  [1,]    1    3    5    7    9   11
    #  [2,]    2    4    6    8   10   12
    # dim(x) <- c(2, 5)
    #  Error in dim(x) <- c(2, 5) :
    #   dims [product 10] do not match the length of object [12]
    dim(x) <- c(2, 3, 2)
    class(x)  #  array
    length(dim(x)) # 3
    x
    #  , , 1
    #      [,1] [,2] [,3]
    #  [1,]    1    3    5
    #  [2,]    2    4    6
    #  , , 2
    #      [,1] [,2] [,3]
    #  [1,]    7    9   11
    #  [2,]    8   10   12
    dim(x) <- NULL
    class(x)  #  integer
    x
    #  [1]  1  2  3  4  5  6  7  8  9 10 11 12

Package base version 6.1.5-18
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