Operator Precedence | R Operator Precedence and Associativity - r - learn r - r programming
Operator Precedence
- When multiple operators are used in a single expression, we need to know the precedence of these operators to figure out the sequence of operation that will take place.
- Precedence defines the order of execution, i.e., which operator gets the higher priority.
Example 1: Operator Precedence in R
>3 + 7 * 6
[1] 45
- Here, the * operator gets higher priority than + and hence 3 + 7 * 6 is interpreted as 3 + (7 * 6).
- This order can be changed with the use of parentheses ().
> (3 + 7) * 6
[1] 60
Operator Associativity
- It is possible to have multiple operators of same precedence in an expression. In such case the order of execution is determined through associativity.
- The associativity of operators is given in the table above.
- We can see that most of them have left to right associativity.
Example 2: Operator Associativity in R
>5 / 6 / 7
[1] 0.11904
- In the above example, 5 / 6 / 7is evaluated as (5 / 6) / 7 due to left to right associativity of the / operator. However, this order too can be changed using parentheses ().
>5 / (6 / 7)
[1] 5.83
Precedence and Associativity of different operators in R from highest to lowest
| Operator | Description | Associativity |
|---|---|---|
| ^ | Exponent | Right to Left |
| -x, +x | Unary minus, Unary plus | Left to Right |
| %% | Modulus | Left to Right |
| *, / | Multiplication, Division | Left to Right |
| +, - | Addition, Subtraction | Left to Right |
| <, >, <=, >=, ==, != | Comparisions | Left to Right |
| ! | Logical NOT | Left to Right |
| &, && | Logical AND | Left to Right |
| |, || | Logical OR | Left to Right |
| ->, ->> | Rightward assignment | Left to Right |
| <-, <<- | Leftward assignment | Right to Left |
| = | Leftward assignment | Right to Left |