How to sort a matrix by all columns

Question

Suppose I have

arr = 2 1 3
      1 2 3
      1 1 2

How can I sort this into the below?

arr = 1 1 2
      1 2 3
      2 1 3
         


        

Answer 1

I wrote this little func that does decreasing order as well cols allows to choose which columns to order and their order

ord.mat = function(M, decr = F, cols = NULL){
    if(is.null(cols))
      cols = 1: ncol(M)
    out = do.call( "order", as.data.frame(M[,cols]))
    if (decr)
      out = rev(out)
    return(M[out,])
}