1. 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 a programming language developed by Ross Ihaka and Robert Gentleman at the University of Auckland in 1993

Why use R for statistical computing and graphics?

Application of R programming in the real world

How to download & install R, R studio

1.1 R as a calculator

1.1.1 Performing variuos arithmetic operations: Addition(+),Subtraction(-), multiplication(*), exponent(^) etc

25+3
## [1] 28
25-3
## [1] 22
25*3
## [1] 75
25/3   # division
## [1] 8.333333
25%/%3 # given the integer value when 25 is divided by 3
## [1] 8
2**3
## [1] 8
2^3
## [1] 8

1.1.2 Builtin functions

Built-in functions refer to a set of pre-defined functions

exp(6)
## [1] 403.4288
sqrt(36) #square root of 36
## [1] 6
sum(2,3,4,5,6)
## [1] 20
log(64)
## [1] 4.158883
log(10,2) #log 10 to base 2
## [1] 3.321928
log(42,10)#log 42 to the base 10
## [1] 1.623249
log(5,3)
## [1] 1.464974
factorial(5) # 5!= 1*2*3*4*5
## [1] 120
abs(-8.5)#absolute value
## [1] 8.5
floor(3.8)  #greatest integer less than 3.8
## [1] 3
ceiling(3.2) #next integer to 3.2
## [1] 4
rep(35,times=10) #repeate 35 10 times
##  [1] 35 35 35 35 35 35 35 35 35 35
rep("Happy", times=5)
## [1] "Happy" "Happy" "Happy" "Happy" "Happy"
## [1] "Happy" "Happy" "Happy" "Happy" "Happy"
5:9  # display numbers from 5 to 9
## [1] 5 6 7 8 9
1:100
##   [1]   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18
##  [19]  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36
##  [37]  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54
##  [55]  55  56  57  58  59  60  61  62  63  64  65  66  67  68  69  70  71  72
##  [73]  73  74  75  76  77  78  79  80  81  82  83  84  85  86  87  88  89  90
##  [91]  91  92  93  94  95  96  97  98  99 100
seq(5,9) # generates a sequence of numbers from 5 to 9,
## [1] 5 6 7 8 9
seq(5,10,0.5) #generates a sequence of numbers starting from 5, incrementing by 0.5 till 10
##  [1]  5.0  5.5  6.0  6.5  7.0  7.5  8.0  8.5  9.0  9.5 10.0
seq(1,50,5)
##  [1]  1  6 11 16 21 26 31 36 41 46

1.1.3 Relational Operators

Relational operators in R are used to compare values and determine the relationship between them.

2<5
## [1] TRUE
3>9
## [1] FALSE
2+3==6 #to check whether 'is equal to'
## [1] FALSE
2!=3 #to check whether 'not equal to'
## [1] TRUE

1.2 Assigning value to a variable

we can assign a value to a variable using the assignment operator <- or the equal sign = syntax: variable_name <- value

x <- 48  # x is assigned the value 48
print(x)
## [1] 48
x/5
## [1] 9.6
x*2
## [1] 96
y<-"Happy"
rm(x) #to remove x from memory
rm(y)

1.3 Vectors

In R, a vector is a fundamental data structure that can hold a collection of values of the same data type. Vectors are essential in R and are used extensively in data analysis, statistics, and programming. c() is used to create vectors.

a<-c(20,30,40,45,56) #easiest way to create a vector in R

str(a)  #  it will provide information about the data type of a and its contents
##  num [1:5] 20 30 40 45 56
print(a)
## [1] 20 30 40 45 56
View(a)

Subsetting (operator [ ])

Subsetting using the [ ] operator in R allows you to extract specific elements or subsets of elements from an object

a[3] # to extract third value or subset of vector "a" with 3rd element
## [1] 40
a[5]
## [1] 56
a[c(1,3,5)] #to extract several values
## [1] 20 40 56
a[-2] #to drop second value
## [1] 20 40 45 56
a[-3]
## [1] 20 30 45 56
a[c(-2,-5)]# to drop 2nd and 5th value
## [1] 20 40 45
length(a) # To find number of elements
## [1] 5

Find the class of a vector

a1<-c(20,30,40,45,56) 
class(a) # To find class of a vector
## [1] "numeric"
m <- c(5, 'a', -1, 2)
class(m)
## [1] "character"
m<-c(TRUE,F,T,FALSE)
class(m) 
## [1] "logical"
sapply(m, class)  # display class of all elements
## [1] "logical" "logical" "logical" "logical"

#Operations on vectors

b<-c(1,2,3,4,5)
a+b
## [1] 21 32 43 49 61
a*b
## [1]  20  60 120 180 280
a-b
## [1] 19 28 37 41 51

Question 1

Construct a vector with elements -2,3,-6,10,7 and assign it as X and another vector with elements 11,23,14,52,16 and assign it as Y a) Find length of X and Y b) Remove 2 nd element from Y c) Find 4th element of X d) Find X+Y , X*Y e) Find Y/X and round to 1 decimal place

X<-c(-2,-3,-6,10,7)
Y<-c(11,23,14,52,16)
length(X)
## [1] 5
length(Y)
## [1] 5
Y[-2]
## [1] 11 14 52 16
X[4]
## [1] 10
X+Y
## [1]  9 20  8 62 23
X*Y
## [1] -22 -69 -84 520 112
round(Y/X,1) 
## [1] -5.5 -7.7 -2.3  5.2  2.3
data <- c("apple", 3.14, 42, TRUE)
class(data[2])
## [1] "character"

Practice Questions

Question 1:

Create a vector grades with elements “A”, “B”, “C”, “D”, “F”. Change the third element to “B+”.

Question 2:

Create a vector temperatures with elements 72, 68, 75, 80, 77. Convert the temperatures from Fahrenheit to Celsius using the formula (Fahrenheit - 32) * 5/9. Round the Celsius temperatures to one decimal place.

Question 3:

Create two vectors, vector1 with elements 1 to 5 and vector2 with elements 6 to 10. Calculate the product of these vectors.

Question 4:

Create a vector names with elements “John”, “Jane”, “Bob”, “Alice”, “Eve”. Extract the first three elements of the vector and store them in a new vector called subset_names.

Question 5:

Create a vector data with the following values: “apple”, 3.14, 42, TRUE. Find the class of each element in the vector and store the results in a new vector called data_classes.