1. Introduction to R

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

2. Basics of R

a. R as Calculator

## [1] 15
## [1] 10
## [1] 50
## [1] 20

b. Function

A function performs a specific task when called.

Types of Function:

Types Functions
Built-in print(), sum(), mean()
User-defined eg: add.me()
## [1] "My name is Binod"
## [1] 5050
## [1] 5
## [1] 10
## [1] 10
## [1] 4
## [1] 3

c. Assignment

  • Process to store values
  • The <- operator is used for assignment.
  • We assign values in a variable.
## [1] 1275
## [1] 5

d. Mutiplication Table

## Type a number:
## [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. Data Structures in R

To make best out of R, you need solid basics of data structures and how to operate on those.

To understand computations in R, two slogans are helpful:

Dimension Type
- Homogeneous Heterogeneous
1D Vector List
2D Matrix Data Frame
nD Array* -

Note: Homogeneous allow only single data types.

3.1 Vector

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

Type Example
Logical TRUE, FALSE
Integer 2L, 5L (L defines as integer)
Numeric 2, 5.5 (Double i.e ‘real number’)
Complex 1+3i
Character “apple”, “ball”

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

Function Description
class() what kind of object is it (high-level)?
typeof() what is the object’s data type (low-level)?
length() how long is it? What about two dimensional objects?
attributes() does it have any metadata?

a. Creating a vector

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

3.2 List

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

a. Creating a list

c. Creating student’s list

## $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

d. Checking the list elements

## $name
## [1] "Anu"    "Bikash" "Saroj"
## [1] 20 24 27

3.3 Matrix

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

b. Create two vectors x and y

c. Combine two vectors by row or col

d. Check dimension of vectors

## [1]  2 10
## [1] 10  2

3.4 Data Frame

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

a. Creating data frame

b. Creating student data frame

c. Useful functions for Data Frame

Functions Description
head() see first 6 rows
tail() see last 6 rows
dim() see dimensions
nrow() number of rows
ncol() number of columns
str() structure of each column
names() will list the names attribute for a data frame (or any object really), which gives the column names.