7 Operators in R

Let us learn various operators in R.

7.1 Assignment Operators

So far we have been using = notation to assgin values to an object. For example age = c(10, 11, 12) indicates we are storing the age of three individuals to an object age with the assignment sign =. R has another way to assign object to its values.

Assignment Operators in R
Operator	Description	Example
`=`	Assign the value to the object on the left	`x = 10`
`<-`	Assign the value to the object on the left	`x <- 10`
`->`	Assign the value to the object on the right	`10 -> x`

We mostly use the = or the <- operators to assign values to ab object. It is recommended to use <- operator to avoid any confusion in cases such as the following.

x = 5
x = x == 3 # checking if the value of x is 3
x

[1] FALSE

Much readable with <- operator

x = 5
x <- x == 3 # checking if the value of x is 3
x

[1] FALSE

7.2 Arithmetic Operators

These are the operators for performing computation with numerical data type

Arithmetic Operators in R
Operator	Description	Sample Code	Output
+	Addition	`10 + 10`	20
-	Subtraction	`10 - 8`	2
*	Multiplication	`5 * 10`	50
/	Division	`50 / 10`	5
^	Exponent	`10 ^ 2`	100
%/%	Integer division	`20 %/% 3`	6
%%	Modulus (remainder)	`10 %% 3`	1
%*%	Matrix multiplication	see below	see below

Let us define the two matrices as follows

mat_a = matrix(c(10, 20, 30, 40), nrow = 2)
mat_b = matrix(c(1, 2, 3, 4), nrow = 2)

mat_a

     [,1] [,2]
[1,]   10   30
[2,]   20   40

mat_b

     [,1] [,2]
[1,]    1    3
[2,]    2    4

# Element wise multiplication
mat_a * mat_b

     [,1] [,2]
[1,]   10   90
[2,]   40  160

# True matrix multiplication
mat_a %*% mat_b

     [,1] [,2]
[1,]   70  150
[2,]  100  220

7.3 Relational Operators

Relational operators return boolean output.

Relational Operators in R
Operator	Description	Example	Output
>	Greater than	`5 > 2`	TRUE
<	Less than	`5 < 2`	FALSE
>=	Greater than or equal to	`10 >= 10`	TRUE
		`c(1, 10) >= c(-2, 20)`	TRUE, FALSE
<=	Less than or equal to	`100 <= 100`	TRUE
		`c(1, 10) <= c(-2, 20)`	FALSE, TRUE
==	Equal to	`10 == 10`	TRUE
		`'Male' == 'M'`	FALSE
		`'Male' == ' Male'`	FALSE
		`'Male' == 'male'`	FALSE
!=	Not equal to	`10 != 9`	TRUE
		`'Male' != 'male'`	TRUE

7.4 Logical Operators

Logical operators also return boolean values TRUE or FALSE

Logical Operators in R
Operator	Description	Example	Output
!	Logical NOT
&	Element-wise Logical AND
\|	Element-wise Logical OR
&&	Logical AND
\|\|	Logical OR

For the && and || operators, I will not discuss here. But if you are interested, read the documentation which reads.

The “short-circuit” operators && and || are often used as part of the condition in an if statement. Whereas & and | apply element-wise to vectors, && and || apply to vectors of length one, and only evaluate their second argument if necessary.

The full R official documentation can be accessed here.

7.5 Examples of logical operators

To negate the condition, we prefix with the ! sign. != means not equal to. That is, we are negating the equality. Lets see some examples

x = 3
x == 3 # its TRUE

[1] TRUE

!(x == 3) # when negated, it should be false

[1] FALSE

x != 3 # equivalent to the previous one

[1] FALSE

7.6 Element-wise Logical AND example

7.7 Logical AND

df = data.frame(
    serial = 1:5,
  age = c(10, 11, 20, 30, 32), 
  sex = c('M', 'F', 'F', 'M', 'M')
)

df

  serial age sex
1      1  10   M
2      2  11   F
3      3  20   F
4      4  30   M
5      5  32   M

df$age == 10 & df$sex == 'M'

[1]  TRUE FALSE FALSE FALSE FALSE