R – Functions

R Function consist of 4 parts:

  • Formals () – list of argument supplied to function
  • Environment () –which stores the function name as an object
  • Body () – contains list of statements that decides the task of this function name
  • Return() – it returns the result of function call immediately from the function.

Example:

> func_name <- function(a)

+ a=10

> func_name <- function(a)a=10

> environment(func_name)

<environment: R_GlobalEnv>

> body(func_name)

a = 10

> formals(func_name)

$a

> check <- function(t) {

+ if (t == red) {

+ return(“STOP”)

+ }

+ else if (t ==green) {

+ return(“GO”)

+ }

+ else {

+ return(“WAIT”)

+ }

+ }



R Functions are of 2 types:

  • User defined function
  • Built-in function

User Defined Function:

One of the useful feature of R programming is its ability to allow programmer to create user defined functions.

Example

Here I am defining a function “fun” which will add 2 numbers

> fun <- function (a, b) {

+ a + b

+ }

> fun (5, 12)

[1] 17

Built-in Functions:

R programming comes up with a number of built in functions. Mostly they are of the following types:

  • Numeric Functions
  • Character Functions
  • Statistical Functions

Numeric Functions:

  • Floor(x) – floor (5.7) gives 5
  • Ceiling(x) – ceiling (5.2) gives 6
  • Trunc(x) – trunc(2.137) gives 2
  • Abs(x) – abs(-3.4) gives 3.4
  • Sqrt(x) – sqrt(25) gives 5
  • Round(x, digit=n) – round(2.137, digit=2) gives 2.14
  • Log(x) – log(5) gives natural logarithm of 5 which is 1.609438
  • Log10(x) – log10(5) gives common logarithm of 5 which is 0.69897
  • Sum(x) – sum (5 +6) gives 11

Character Functions

  • Toupper(x) – toupper(“RamEswaRam”) gives “RAMESWARAM”
  • Tolower(x) – tolower(“RamEswaRam”) gives “rameswaram”
  • Grep() –used for keyword search.
  • > str <-c(“are” ,”Delaware is a malware”,” But its not a hardware”)
  • > total <- grep (“are”, str, value=F)
  • > total
  • [1] 1 2 3
  • sub()—used for keyword substitution
  • > total <- sub (“are”,”aks”, str)
  • > total
  • [1] “aks”                     “Delawaks is a malware”
  • [3] ” But its not a hardwaks”

Statistical Functions:

  • mean ()
  • median ()
  • mode ()
  • min ()
  • max ()
  • range()
  • sd()

Read more about Statistical use of R programming in the “Use of R Programming in Statistics” segment Click Here