How can I create an infix %between% operator?

Question

I would like to have an infix operator %between% in R -- to check to see if x is between lower bound l and upper bound u.

I have created the following simple function -- but it's not an infix operation.

# between function - check to see if x is between l and u is.between <- function(x, l, u) { x > l & x < u } 

My aim is to replace this with: x %between% c(l, u)

Is it possible to define new infix operations? If so, how does one do this?

thanks in advance

Answer 1

You can define infix operators as functions:

`%between%`<-function(x,rng) x>rng[1] & x<rng[2] 1 %between% c(0,3) # [1] TRUE 1 %between% c(2,3) # [1] FALSE 

As pointed out by @flodel, this operator is vectorized:

1:5 %between% c(1.5,3.5) # [1] FALSE  TRUE  TRUE FALSE FALSE 

Answer 2

This function exists in the package data.table (with the slight difference that the bounds are included), implemented as:

between <- function(x,lower,upper,incbounds=TRUE) {   if(incbounds) x>=lower & x<=upper   else x>lower & x<upper }  "%between%" <- function(x,y) between(x,y[1],y[2],incbounds=TRUE) 

It can be used as between(x,lower,upper) or x %between% c(lower, upper)