Functions

Overview

Teaching: min
Exercises: min

Questions

Objectives

• Understand the use of functions in R

• Understand how to use built in functions in R

• Understand how to create your own functions in R

FUNCTIONS

Function arelines of codes which are executed in a sequential order in order to perform a certain task. In other words, it is a set of statements which are executed together to accomplish a certain task. R like any programming language, has many built in functions (also called pre-defined functions) but also allows users to create their own functions which are known as user defined functions.

BUILT IN FUNCTIONS

These are functions which are built inside R which are readily available for all users with access to R. E.g.:
seq()-Print a sequence of numbers
mean()-Find the mean value of a set of numbers
sum()-Find the sum of a set of numbers

seq(25,35)

results in:

[1] 25 26 27 28 29 30 31 32 33 34 35

You can refer Link1[FIXME link] & Link2 [FIXME link] for some of the most frequently used bult in R functions.

USER DEFINED FUNCTION

These are functions which are manually defined by user and are not available in R by default. Users can create a function based on their own requirements. These functions are useful when a block of code is required to be performed repetitively.
Syntax:

function_name <- function(argument1,argument2, .............)
  {
  Body of the function (or) statements
  return()
  }

Calling the function:

function_name()

Key Points

• First key point. Brief Answer to questions. (FIXME)