Matrix or Array Rotation by 90 Degrees

rotate90(img, direction = "positive")

Arguments

img: an array or a matrix
direction: The direction of rotation by 90 degrees. The value can be "positive" (default) or "negative". Aliases are "counterclockwise" and "clockwise", respectively.

Value

an array or a matrix (rotated by 90 degrees)

Details

The function takes an array or matrix as input object (img) and returns the object rotated by 90 degrees. Per default, the rotation is done in the mathematically positive direction (i.e., counterclockwise). Clockwise rotation (i.e., mathematically negative) can be specified by passing the value "negative" to the direction argument.

Examples

# sample matrix
img <- matrix(1:6, ncol = 2)
img
#>      [,1] [,2]
#> [1,]    1    4
#> [2,]    2    5
#> [3,]    3    6

rotate90(img) # counterclockwise
#>      [,1] [,2] [,3]
#> [1,]    4    5    6
#> [2,]    1    2    3
rotate90(img, direction = "negative") # clockwise
#>      [,1] [,2] [,3]
#> [1,]    3    2    1
#> [2,]    6    5    4