Clip values between a minimum and maximum allowed value in R

Question

In Mathematica there is the command Clip[x, {min, max}] which gives x for min<=x<=max, min for x<min and and max for x>max, see

http://reference.wolfram.com/mathematica/ref/Clip.html (mirror)

What would be the fastest way to achieve this in R? Ideally it should be a function that is listable, and should ideally work on either a single value, vector, matrix or dataframe...

Answer 1

Rcpp has clamp for this:

cppFunction('NumericVector rcpp_clip( NumericVector x, double a, double b){     return clamp( a, x, b ) ; }') 

Here is a quick benchmark showing how it performs against other methods discussed :

pmin_pmax_clip <- function(x, a, b) pmax(a, pmin(x, b) ) ifelse_clip <- function(x, a, b) {   ifelse(x <= a,  a, ifelse(x >= b, b, x)) } operations_clip <- function(x, a, b) {   a + (x-a > 0)*(x-a) - (x-b > 0)*(x-b) } x <- rnorm( 10000 ) require(microbenchmark)  microbenchmark(    pmin_pmax_clip( x, -2, 2 ),    rcpp_clip( x, -2, 2 ),    ifelse_clip( x, -2, 2 ),    operations_clip( x, -2, 2 ) ) # Unit: microseconds #                        expr      min        lq   median        uq       max # 1     ifelse_clip(x, -2, 2) 2809.211 3812.7350 3911.461 4481.0790 43244.543 # 2 operations_clip(x, -2, 2)  228.282  248.2500  266.605 1120.8855 40703.937 # 3  pmin_pmax_clip(x, -2, 2)  260.630  284.0985  308.426  336.9280  1353.721 # 4       rcpp_clip(x, -2, 2)   65.413   70.7120   84.568   92.2875  1097.039