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R Programming : Operators

Tutorial by:Maria Ghoste      Date: 2016-06-10 00:18:07

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

Type of operators in R
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.

Arithmetic Operators 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.

Relational Operators 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.

Logical Operators in R
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.

Assignment Operators in R
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

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