R Infix Operator

In this article, you’ll learn about infix operators; how they actually work in R and how you can create an infix operator yourself. Also, you’ll learn different predefined infix operators in R programming.

Most of the operators that we use in R are binary operators (having two operands). Hence, they are infix operators, used between the operands. Actually, these operators do a function call in the background.

For example, the expression a+b is actually calling the function `+`() with the arguments a and b, as `+`(a, b).

Note: the back tick (`), this is important as the function name contains special symbols.

Following are some example expressions along with the actual functions that get called in the background.

Example: How infix operators work in R?

> 5+3
[1] 8
> `+`(5,3)
[1] 8
> 5-3
[1] 2
> `-`(5,3)
[1] 2
> 5*3-1
[1] 14
> `-`(`*`(5,3),1)
[1] 14

It is possible to create user-defined infix operators in R. This is done by naming a function that starts and ends with %.

Following is an example of user-defined infix operator to see if a number is exactly divisible by another.

Example: User defined infix operator

`%divisible%` <- function(x,y)
if (x%%y ==0) return (TRUE)
else          return (FALSE)

This function can be used as infix operator a %divisible% b or as a function call `%divisible%`(a, b). Both are the same.

> 10 %divisible% 3
> 10 %divisible% 2
[1] TRUE
> `%divisible%`(10,5)
[1] TRUE

Things to remember while defining your own infix operators are that they must start and end with %. Surround it with back tick (`) in the function definition and escape any special symbols.

Predefined infix operators in R

Predefined infix operators in R
%% Remainder operator
%/% Integer division
%*% Matrix multiplication
%o% Outer product
%x% Kronecker product
%in% Matching operator