Rotate a Matrix in R

Question

I have a matrix in R like this:

|1|2|3|
|1|2|3|
|1|2|3|

Is there an easy way to rotate the entire matrix by 90 degrees clockwise to get the

Answer 1

An easy way to rotate a matrix by 180° is this:

m <- matrix(1:8,ncol=4)
#      [,1] [,2] [,3] [,4]
# [1,]    1    3    5    7
# [2,]    2    4    6    8


rot <- function(x) "[<-"(x, , rev(x))

rot(m)
#      [,1] [,2] [,3] [,4]
# [1,]    8    6    4    2
# [2,]    7    5    3    1

rot(rot(m))
#      [,1] [,2] [,3] [,4]
# [1,]    1    3    5    7
# [2,]    2    4    6    8