R Programming Language

History and Introduction
 R is a programming language and free software environment for statistical
computing and graphics supported by the R Foundation for Statistical Computing.
 R is widely used by statisticians, data analysts and researchers for developing
statistical software and data analysis.
 It compiles and runs on a wide variety of UNIX platforms, Windows and Mac OS.
 The copyright for the primary source code for R is held by the R Foundation and is
published under the GNU General Public License version 2.0.
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 R was created by Ross Ihaka and Robert Gentleman at the University of Auckland, New
Zealand.
 Currently R is developed & maintained by the R Development Core Team.
 The Applications of R programming language includes :
1.Statical Computing
2.Machine Learning
3.Data Science
 R can be downloaded and installed from CRAN(Comprehensive R Archive Network) website.
 R language is cross platform interoperable and fully portable which means R program that
you write on one platform can be carried out to other platform and run there.(Platform
independent)

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Top Tier companies using R – companies all over the world use R language for statical analysis.
These are some of top tier companies that uses R.
Company Name Applications
Facebook For behavior analysis related to status updates and profile pictures.
Google For advertising effectiveness and economic forecasting.
Twitter For data visualization and semantic clustering
Microsoft
Acquired Revolution R company and use it for a variety of
purposes.
Uber For statistical analysis
Airbnb Scale data science.

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Evolution of R
R is a dialect of S language…
 It means that R is an implementation of the S programming language combined
with lexical scoping semantics & inspired by Scheme.
 S language was created by John Chambers in 1976 at Bell Labs.
 A commercial version of S was offered as S-PLUS starting in 1988.
S version1
S version 2
S version 3
S version4

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Features of R
These are the some of important features of R -
 R is a simple, effective and well-developed, programming language which
includes conditionals, loops, user defined & recursive functions and input &
output facilities.
 R provides a large, coherent and integrated collection of tools for data
analysis.
 R has an effective data handling and storage facility.
 R provides a suite of operators for calculations on arrays, lists, vectors and
matrices.
 R provides graphical facilities for data analysis and display either directly at
the computer or printing at the papers.

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Features of R
Fast Calculation
Extremely Compatible
Open Source
Cross Platform Support
Wide Packages
Large Standard Library
 Fast Calculation - R can be used to perform complex mathematical
and statistical calculations on data objects of a wide variety.
 Extreme Compatibility - R is an interpreted language which means
that it does not need a compiler to make a program from the code.
 Open Source - R is an open-source software environment. You can
make improvements and add packages for additional functionalities
 Cross Platform Support - R is machine-independent. It supports
the cross-platform operation. Therefore, it can be used on many
different operating systems.
 Wide Packages - CRAN houses more
than 10,000 different packages and extensions that help solve all
sorts of problems in data science.
 Large Standard Library - R can produce static graphics with
production quality visualizations and has extended libraries
providing interactive graphic capabilities.

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Syntax of R
Once we have R environment setup, then it’s easy to start our R command prompt by just
typing R in command prompt.
Hello World Program –
>myString <- “Hello world !”
>print(myString)
Output :
[1] “Hello World !”
The [ ] in the output of R can be used
to reference data frame columns
In the Syntax of R we will discuss –
 Data Types
 Variables
 Keywords
 Operators
 Data Structures

Data Types
Logical
Integer
Character
Numeric
raw
Complex
Data
Types
In R there are basically 6 data types –
Data Type Examples
Integer 2L,5L,8L
Numeric 6,2,1,9
Logical true,false,0,1
raw Raw Bytes
complex Z=3+7i
Character ‘A’ , ”Aditya” , ”AB12”
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Variables
Rules For Naming Variables in R –
1. In R variable name must be a combination of letters, digits, period(.) and
underscores.
2. It must start with a letter or period(.) and if it starts with period then it period
should not be followed by number.
3. Reserved words in R cannot be used in variable name.
Valid variables Invalid Variables
 myValue
 .my.value.one
 my_value_one
 Data4
 .1nikku
 TRUE
 vik@sh
 _temp

Keywords
Reserved Keywords in R – Reserved words are set of words that have special meaning
and cannot be used as names of identifiers.
If Else Repeat While Function
For In Next Break TRUE
FALSE NULL inf NaN -
Reserved Keywords in R
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Operators
In any programming language, an operator is a symbol which is used to represent an
action. R has several operators to perform tasks including arithmetic, logical and bitwise
operations.
Operators in R can mainly be classified into the following categories –
1.Arithmetic Operators = {+ , - , * , / , %% , %/%}
2.Logical Operators = { ! , & , && , | , ||}
3.Assignment operators = { <- , <<- , = , -> , ->>}
4.Relational Operators = { < , > , <= , >= , != , ==}

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Functions
Functions are used to incorporate sets of instructions that you want to use repeatedly. There are two types of functions.
Function
Built In User Defined

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Built - In
Built-in functions are those functions which are provided by R so that we can use directly
within the language and its standard libraries.
In R there are so many built-in functions which make our programming fast and easy.
For Example :
1.The sum(a,b) function will return (a+b)
>print(sum(10,20))
[1] 30
2.The seq(a,b) function is used to get sequence from a to b.
>print(seq(5,15))
[1] 5 6 7 8 9 10 11 12 13 14 15

User Defined
User defined functions are those functions which we define in our code and use them
repeatedly. These functions can be defined with two types.
1.Without Arguments 2.With Arguments
Without Arguments With Arguments
myFunction <- function()
{
#This will be printed on calling this funcition
print(“Without Arguments”)
}
myFunction <- function(a,b)
{
#This function will print sum of passed args
print(a+b)
}

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Conditional Statements
 Conditional Statements in R programming are used to make decisions based on the conditions.
 Conditional statements execute sequentially when there is no condition around the statements.
In R language we’ll discuss 3 types of Conditional Statements –
1.If - else statements
2.If – else if – else statements
3.Switch statements

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If-else
Start
Execute
Else block
End
Execute
If Block
Condition
True?
yes no
Syntax –
If(condition) {
expression 1
}
Else {
expression 2
}
Example –
If(a>b) {
print(“a is greater than b”)
}
Else {
print(“ a is less than b”)
}

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Switch statement
 In switch() function we pass two types of arguments one is value and others is list of
items.
 The expression is evaluated based on the value and corresponding item is returned.
 If the value evaluated from the expression matches with more than one item of the
list then switch() function returns the item which was matched first.
Examples:
> switch(2,”Delhi”,”Jaipur”,”Mumbai”) > a=3
>[1] “Jaipur” > switch(a,”red”,”blue”,”green”,”yellow”)
> [1] “green”

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Loops
Loops
In
R
Loops are used When we need to
execute particular code
repeatedly.
In R Language there are 3 types
of Loops –
1.For Loop
2.While Loop
3.Repeat Loop

For Loop
Example to count the number of even numbers in a
vector.
Program -
x <- c(2,5,3,9,8,11,6)
count <- 0
for (i in x) {
if(i %% 2 == 0) {
count=count+1
}
}
print(count)
Output -
[1] 3
No
Last item
Reached??
Body of
For Loop
Exit Loop
Yes
For each item
in Sequence
A for loop is used to iterate over a vector in R programming.
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While Loop
In R programming, while loops are used to loop until a specific condition is met.
Program –
i <- 1
while(i<5) {
print(i)
i=i+1
}
Output –
[1] 1
[1] 2
[1] 3
[1] 4
Yes
No
Condition
True??
Execute code
of while block
Start
Execute code
outside while block

Repeat Loop
 A repeat loop is used to iterate over a block of code multiple number of times.
 There is no condition check in repeat loop to exit the loop.
 We must ourselves put a condition explicitly inside the body of the loop and use the break statement to
exit the loop. Failing to do so will result into an infinite loop.
Example –
x <- 1
repeat {
print(x)
x = x+1
if (x == 4) {
break
}
}
Output –
[1] 1
[1] 2
[1] 3
Body of
Loop
Break
?
Remaining
body of loop Exit
Enter Loop
Yes
No
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Data Structures
Data
Structures
Vectors
Factors
Data
Frames
Lists
Matrices
Arrays
A data structure is a particular way of
organizing data in a computer so that it can
be used effectively. The idea is to reduce
the space and time complexities of different
tasks. Data structures in R programming are
tools for holding multiple values.
The most essential data structures used in R include :
 Vectors
 Arrays
 Factors
 Lists
 Matrices
 Data Frames

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Vector
 Vector is the one of basic data structure of R which supports integer,
double, Character, logical, complex and raw data types.
 The elements in a vector are known as components of a vector.
Vector Creation
Vector can be created using these two methods :-
1.By Using Colon(:) Operator –
a <- 2:8
print(a) # 2 3 4 5 6 7 8
2.By Using seq() function–
a <- seq(2,10,by=2)
print(a) # 2 4 6 8 10

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Vector
Vector Operations
1.Combining Vectors 2.Arithmetic Operations
a <- c(4,3,5) a <- c(1,2,3)
b <- c(‘x’,’y’,’z’) b <- c(4,5,6)
c <- c(a,b) d <- a+b
print(c) o/p= 4 3 5 x y z print(d) o/p = 5 7 9
3.Numeric Indexing 4.Duplicate Indexing
a <- c(4,3,5) a <- c(4,3,5)
Print(a[2]) op = 5 print(a[1,2,2,3,3]) o/p=4 3 3 5 5
5.Logical Indexing 6.Range Indexing
a <- c(4,3,5) a <- c(1,2,3,4,5,6,7)
print(a[true,false,true]) o/p = 4 5 print(a[2:6]) o/p = 2 3 4 5 6

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Array
Arrays allow us to store data in multi - dimensions and use in efficient way.
array Creation
Syntax -
Array_Name <- array(data, dim=(row_size,column_size,matrices), dim_names)
array Operations
1.Accessing Array Elements –
Accessing array in R is similar to other programming languages like c,c++ and java.
Eg. Print(Arr[2,2])
2.Arithmetic Operations –
Eg. Arr3 <- Arr2 + Arr1
Or
Arr3 = Arr1 – Arr2

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Data Frame
Data Frame is a table or a two dimensional Array type structure.
Important Considerations
 The Column names should be non-empty.
 The row names should be unique.
 The Data stored in Data Frames can be only Numeric, Factor or Character Type.
 Each column should contain same number of data types.
Data Frame Creation
products <-data.frame(
product_number = seq(1:4)
product_name = c(“Apple”,”Samsung”,”Redmi”,”Oppo”))
print(products)
Product_number Product_name
1 Apple
2 Samsung
3 Redmi
4 Oppo

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Lists
 List is a data structure which have components of Mixed data types.
 So a vector having elements of different data types is called a list.
 List can be created using list() function.
Eg. –
x <- list( a=“amba”,b=9.23,c=TRUE) #list storing 3 different data types
Accessing List Elements
print(x[‘b’]) o/p = 9.23
print(x[‘a’]) o/p = “amba”
Manipulating List Elements
x[‘a’] <- “nitin”
print([‘a’]) o/p = “nitin”

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Matrices
 In R two dimensional rectangular data set is known as Matrix.
 A Matrix is created with the help of the input vector to the matrix() function.
 We can Perform addition, subtraction, multiplication and division operations on matrices.
Creating matrix -
Matrix1 <- matrix (2:7,nrow=2,ncol=3)
print(Matrix1)
o/p = 2 4 6
3 5 7
Accessing Elements –
Matrix1[2,3] # 7
Assigning Value –
Matrix1[2,3]=1

Matrices
Operations On Matrices
1.Addition :
Matrix3=Matrix1+Matrix2
2.Subtraction :
Matrix3 = Matrix2 – Matrix1
3.Multiply by a Constant :
Ex : 7*Matrix1
4.Identity Matrix :
Ex – diag(5)
5.Transposition
Ex – t(Matrix1)
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Factors
Factors are data objects which are used to categorise the data and store it as levels.
For example: a data field such as marital status may contain only values from single, married,
separated, divorced, or widowed.
>x
[1] single married married single
Levels : married single
Here, we can see that factor x has four elements and two levels. We can check if a variable is a
factor or not using class() function.
>class(x)
[1] “factor”
>levels(x)
[1] married single

R - Studio
Interacting with R Studio –
 R-Studio is a free and open-source integrated development
environment (IDE) for R, a programming language for statistical
computing and graphics.
 R-Studio was founded by JJ Allaire,creator of the programming
language ColdFusion.
 There are 4 main sections in R-Studio IDE…
1.Code Editor
2.Workspace and History
3.R console
4.Plots and Files

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R - Studio
 RStudio is available in two editions:
1.RStudio Desktop, where the program is run
locally as a regular desktop application.
2.RStudio Server, Prepackaged distributions of
RStudio Desktop are available for Windows, OS
X, and Linux.
 RStudio is written in the C++ programming
language and uses the Qt framework for its
graphical user interface.

R Programming Language

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