Beginners Guide to R

Beginners Guide to R – R Operators

By on Monday, May 10, 2021

R Operators

Operators are used to perform operations on values and variables. The R operators are classified into six different categories:

  • Arithmetic operators
  • Comparison operators
  • Logical operators
  • Element-wise Logical operators
  • Membership operators
  • Assignment operators

 

Arithmetic Operators

Arithmetic operators are used to perform simple mathematical operations on numeric values and vectors.

Operator Meaning Example
+ Addition x + y
– Subtraction x – y
* Multiplication x * y
/ Division x / y
%% Modulus x %% y
^ Exponents x ^ y
%/% Integer division x %/% y

Here are some examples:

# Operations on numeric values
x <- 6
y <- 2

# addition
x + y
[1] 8

# subtraction
x - y
[1] 4

# multiplication
x * y
[1] 12

# division
x / y
[1] 3

# modulus
x %% y
[1] 0

# exponents
x ^ y
[1] 36

# integer division
x %/% y
[1] 3

All the basic arithmetic operators can be performed on pairs of vectors. Each operation is performed in an element-by-element manner.

# Operations on vectors
v1 <- c(11,12,13,14,15)
v2 <- c(1,2,3,4,5)

# addition
v1 + v2
[1] 12 14 16 18 20

# subtraction
v1 - v2
[1] 10 10 10 10 10

# multiplication
v1 * v2
[1] 11 24 39 56 75

# division
v1 / v2
[1] 11.000000  6.000000  4.333333  3.500000  3.000000

# exponents
v1 ^ v2
[1]     11    144   2197  38416 759375

Comparison Operators

Comparison operators are used to compare two values or vectors.

Operator Meaning Example
== Equal to x == y
!= Not equal to x != y
> Greater than x > y
< Less than x < y
>= Greater than or equal to x >= y
<= Less than or equal to x <= y

Here are some examples:

# Operations on numeric values
x <- 6
y <- 2

# equal to
x == y
[1] FALSE

# not equal to
x != y
[1] TRUE

# greater than
x > y
[1] TRUE

# less than
x < y
[1] FALSE

# greater than or equal to
x >= y
[1] TRUE

# less than or equal to
x <= y
[1] FALSE
# Operations on vectors
v1 <- c(11,2,13,4,15)
v2 <- c(1,12,3,14,5)

# equal to
v1 == v2
[1] FALSE FALSE FALSE FALSE FALSE

# not equal to
v1 != v2
[1] TRUE TRUE TRUE TRUE TRUE

# greater than
v1 > v2
[1]  TRUE FALSE  TRUE FALSE  TRUE

# less than
v1 < v2
[1] FALSE  TRUE FALSE  TRUE FALSE

# greater than or equal to
v1 >= v2
[1]  TRUE FALSE  TRUE FALSE  TRUE

# less than or equal to
v1 <= v2
[1] FALSE  TRUE FALSE  TRUE FALSE

Logical Operators

Logical operators are used to join two or more conditions.

Operator Description Example
&& Returns True if both statements are true x > 0 && y < 0
|| Returns True if one of the statements is true x > 0 || y < 0
! Reverses the result, returns False if the result is true !(x > 0 && y < 0) 
x <- 2
y <- -2

# and
x > 0 && y < 0
[1] TRUE

# or
x > 0 || y < 0
[1] TRUE

# not
!(x > 0 && y < 0)
[1] FALSE

Element-wise Logical Operators

These operators are used to perform logical operations on vectors in an element-by-element manner.

Operator Description Example
& Returns True if respective elements of both vectors are true v1 && v2
| Returns True if one of the respective elements of both vectors is true v1 || v2

Here are some examples:

v1 <- c(0,1,2,3,4)
v2 <- c(0,1,0,1,0)

# and
v1 & v2
[1] FALSE  TRUE FALSE  TRUE FALSE

# or
v1 | v2
[1] FALSE  TRUE  TRUE  TRUE  TRUE

Membership Operator

Membership operator is used to check if a specific item is present in the vector or the list.

Operator Description Example
%in% Returns True if a value is present in the vector or the list x %in% y

Here are some examples:

v <- list("red", "green", "blue")

"red" %in% v
[1] TRUE

"blue" %in% v
[1] TRUE

Assignment Operators

Assignment operators are used to assign new values to variables.

Operator Meaning Example
= Assignment x = 3
<-, <<-, = Leftwards assignment x <- 3, x <<- 3, x = 3
->, ->> Rightwards assignment 3 -> x, 3 ->> x

Here are some examples:

x <- 3
x
[1] 3

x = 5
x
[1] 5

9 -> x
x
[1] 9

Miscellaneous Operators

These operators are used to for special purposes.

Operator Description Example
: Generates a number sequence from a to b 1:10
%*% Multiplies two matrices m1 %*% m2

Here are some examples:

# create a sequence
1:10
[1]  1  2  3  4  5  6  7  8  9 10

# multiplies two matrices
m1 <- matrix( c(1,2,3,4), nrow=2, ncol=2, byrow=TRUE)
m2 <- matrix( c(10,20,30,40), nrow=2, ncol=2, byrow=TRUE)
m1 %*% m2
     [,1] [,2]
[1,]   70  100
[2,]  150  220

Operator Precedence (Order of Operations)

In R, every operator is assigned precedence. Operator Precedence determines which operations are performed before which other operations.

Operators of highest precedence are performed first.

Operator Description
highest precedence ( { Function calls and grouping expressions (respectively)
[ [[ Indexing
:: ::: Access variables in a namespace
$ @ Component / slot extraction
^ Exponentiation (right to left)
– + Unary minus and plus
: Sequence operator
%any% Special operators
* / Multiply, divide
+ – (Binary) add, subtract
< > <= >= == != Ordering and comparison
! Negation
& && And
| || Or
~ As in formulas
-> ->> Rightward assignment
= Assignment (right to left)
<- <<- Assignment (right to left)
lowest precedence ? Help (unary and binary)

 

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