a. What is R?

R is an open source programming language designed for statistical computing & graphics.

• Free to use
• Reproducible
• Community support
• Great libraries
• Diverse industries (health, academia to business sector)

Note: Whatever you’re trying to do, you’re probably not the first to try doing it R. Chances are good that someone has already written a package for that.

b. Creating a New file

1. Go to File > R Script

a. R as Calculator

# ADD
5 + 10

## [1] 15

# Subtract
15 - 5

## [1] 10

# Multiply
5 * 10

## [1] 50

# Divide
100 / 5

## [1] 20

b. Function

A function performs a specific task when called.

# print your name
print("My name is Binod")  # what's yours?

## [1] "My name is Binod"

#add 1 to 100
sum(1:100)

## [1] 5050

# mean of 5, 10, 15
mean(5, 10, 15)

## [1] 5

# median 
median(c(5, 10, 15)) 

## [1] 10

# answer
sum(5, 10, 15)/3

## [1] 10

# square root
sqrt(16)

## [1] 4

# User-defined function - add.me()

add.me <- function (x, y) {
   print(x + y)
}

add.me(1, 2)

## [1] 3

c. Assignment

• Process to store values
• The <- operator is used for assignment.
• We assign values in a variable.

total <- sum(1:50)
total

## [1] 1275

avg <- mean(5, 10, 15)
avg

## [1] 5

d. Mutiplication Table

num = as.integer(readline(prompt = "Type a number: "))

## Type a number:

for(i in 1:10) {
  print(paste(num,'x', i, '=', num * i))
}

## [1] "NA x 1 = NA"
## [1] "NA x 2 = NA"
## [1] "NA x 3 = NA"
## [1] "NA x 4 = NA"
## [1] "NA x 5 = NA"
## [1] "NA x 6 = NA"
## [1] "NA x 7 = NA"
## [1] "NA x 8 = NA"
## [1] "NA x 9 = NA"
## [1] "NA x 10 = NA"

3.1 Vector

Vector is one-directional sequence of elements having same data types.

R provides many functions to examine features of vectors and other objects, for example

color <- c("red", "orange", "blue")
color

## [1] "red"    "orange" "blue"

student.name <- c("Anu", "Bikash", "Saroj")
student.age <- c(20, 24, 27)
student.gender <- c("Female", "Male", "Male")
student.married <- c(FALSE, FALSE, TRUE)
student.id <- 1:length(student.name)

typeof(student.age)

## [1] "double"

class(student.age)

## [1] "numeric"

3.2 List

A list is sequence of elements having same or different data types.

lst <- list("Hello", 2, "All")

x <- 1:10
x <- as.list(x)

length(x) # check length of x

## [1] 10

typeof(x) # check type of x

## [1] "list"

student <- list(id = student.id, 
                name = student.name, 
                age = student.age, 
                gender = student.gender, 
                marital.status = student.married)

student

## $id
## [1] 1 2 3
## 
## $name
## [1] "Anu"    "Bikash" "Saroj" 
## 
## $age
## [1] 20 24 27
## 
## $gender
## [1] "Female" "Male"   "Male"  
## 
## $marital.status
## [1] FALSE FALSE  TRUE

student[2] # shows header and values

## $name
## [1] "Anu"    "Bikash" "Saroj"

student[[3]] # shows age

## [1] 20 24 27

3.3 Matrix

Matrix is a collection of data elements arranged in a two-dimensional rectangular layout.

m <- matrix(1:9, nrow = 3)

# other ways to create matrix
m <- 1:10
dim(m) <- c(2, 5)

x <- 1:10
y <- 11:20

z_rowbind <- rbind(x, y)
z_colbind <- cbind(x, y)

dim(z_rowbind)

## [1]  2 10

dim(z_colbind)

## [1] 10  2

3.4 Data Frame

Data frame is a list of vector having equal length and used for storing data tables.

df <- data.frame(id = 1:5, 
                 name= c("Apple", "Ball", 
                         "Cat", "Dog", "Elephant"))
df

student.df <- data.frame(student, stringsAsFactors = F)

student.df