R has many operators to carry out different mathematical and logical operations. Operators in R can mainly be classified into the following categories.

Arithmetic operators |

Relational operators |

Logical operators |

Assignment operators |

## Arithmetic Operators

These operators are used to carry out mathematical operations like addition and multiplication. Here is a list of arithmetic operators available in R.

Operator | Description |
---|---|

+ | Addition |

- | Subtraction |

* | Multiplication |

/ | Division |

^ | Exponent |

%% | Modulus (Remainder from division) |

%/% | Integer Division |

An example run

```
> x <- 5
> y <- 16
> x+y
[1] 21
> x-y
[1] -11
> x*y
[1] 80
> y/x
[1] 3.2
> y%/%x
[1] 3
> y%%x
[1] 1
> y^x
[1] 1048576
```

## Relational Operators

Relational operators are used to compare between values. Here is a list of relational operators available in R.

Operator | Description |
---|---|

< | Less than |

> | Greater than |

<= | Less than or equal to |

>= | Greater than or equal to |

== | Equal to |

!= | Not equal to |

An example run

```
> x <- 5
> y <- 16
> x<y
[1] TRUE
> x>y
[1] FALSE
> x<=5
[1] TRUE
> y>=20
[1] FALSE
> y == 16
[1] TRUE
> x != 5
[1] FALSE
```

### Operation on Vectors

The above mentioned operators work on vectors. The variables used above were in fact single element vectors. We can use the function `c()`

(as in concatenate) to make vectors in R. All operations are carried out in element-wise fashion. Here is an example.

```
> x <- c(2,8,3)
> y <- c(6,4,1)
> x+y
[1] 8 12 4
> x>y
[1] FALSE TRUE TRUE
```

When there is a mismatch in length (number of elements) of operand vectors, the elements in shorter one is recycled in a cyclic manner to match the length of the longer one. R will issue a warning if the length of the longer vector is not an integral multiple of the shorter vector.

```
> x <- c(2,1,8,3)
> y <- c(9,4)
> x+y # Element of y is recycled to 9,4,9,4
[1] 11 5 17 7
> x-1 # Scalar 1 is recycled to 1,1,1,1
[1] 1 0 7 2
> x+c(1,2,3)
[1] 3 3 11 4
Warning message:
In x + c(1, 2, 3) :
longer object length is not a multiple of shorter object length
```

## Logical Operators

Logical operators are used to carry out Boolean operations like `AND`

, `OR`

etc.

Operator | Description |
---|---|

! | Logical NOT |

& | Element-wise logical AND |

&& | Logical AND |

| | Element-wise logical OR |

|| | Logical OR |

Operators `&`

and `|`

perform element-wise operation producing result having length of the longer operand. But `&&`

and `||`

examines only the first element of the operands resulting into a single length logical vector. Zero is considered `FALSE`

and non-zero numbers are taken as `TRUE`

. An example run.

```
> x <- c(TRUE,FALSE,0,6)
> y <- c(FALSE,TRUE,FALSE,TRUE)
> !x
[1] FALSE TRUE TRUE FALSE
> x&y
[1] FALSE FALSE FALSE TRUE
> x&&y
[1] FALSE
> x|y
[1] TRUE TRUE FALSE TRUE
> x||y
[1] TRUE
```

## Assignment Operators

These operators are used to assign values to variables.

Operator | Description |
---|---|

<-, <<-, = | Leftwards assignment |

->, ->> | Rightwards assignment |

The operators `<-`

and `=`

can be used, almost interchangeably, to assign to variable in the same environment. `<<-`

is used for assigning to variables in the parent environments (more like global assignments). The rightward assignments, although available are rarely used.

```
> x <- 5
> x
[1] 5
> x = 9
> x
[1] 9
> 10 -> x
> x
[1] 10
```