1 Introduction

R is a popular programming language used for statistical computing and graphical presentation.

Its most common use is to analyze and visualize data.

1.1 Why to Use R?

  • It is a great resource for data analysis, data visualization, data science and machine learning
  • It provides many statistical techniques (such as statistical tests, classification, clustering and data reduction)
  • It is easy to draw graphs in R, like pie charts, histograms, box plot, scatter plot, etc++
  • It works on different platforms (Windows, Mac, Linux)
  • It is open-source and free
  • It has a large community support
  • It has many packages (libraries of functions) that can be used to solve different problems*

1.2 Install R in your system

To install R, go to https://cloud.r-project.org/ and download the latest version of R for Windows, Mac or Linux.

When you have downloaded and installed R, you can run R on your computer.

1.3 Some Exercise

After installation of R

If you type 5 + 5, and press enter, you will see that R outputs 10.

5+5
## [1] 10

To output text in R, use single or double quotes:

"Hello World!"
## [1] "Hello World!"

To output numbers, just type the number (without quotes):

5
## [1] 5
10
## [1] 10
25
## [1] 25

To do simple calculations, add numbers together:

10-7
## [1] 3

1.3.0.1 Comments

Comments can be used to explain R code, and to make it more readable. It can also be used to prevent execution when testing alternative code.

Comments starts with a #. When executing code, R will ignore anything that starts with #.

This example uses a comment before a line of code:

## Adding 23 and 56
23+56
## [1] 79

1.3.1 Creating Variables in R

Variables are containers for storing data values.

R does not have a command for declaring a variable. A variable is created the moment you first assign a value to it. To assign a value to a variable, use the <- sign (or = sign). To output (or print) the variable value, just type the variable name:

name <- "Bijay Lal Pradhan"
age <- 50

name   # output "Bijay Lal Pradhan"
## [1] "Bijay Lal Pradhan"
age    # output 50
## [1] 50

1.4 Concatenate Elements

You can also concatenate, or join, two or more elements, by using the paste() [or cat] function.

To combine both text and a variable, R uses comma (,):

text <- "awesome"

paste("R is", text)
## [1] "R is awesome"

1.4.1 Variable Names

A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume). Rules for R variables are: A variable name must start with a letter and can be a combination of letters, digits, period(.) and underscore(). If it starts with period(.), it cannot be followed by a digit. A variable name cannot start with a number or underscore () Variable names are case-sensitive (age, Age and AGE are three different variables) Reserved words cannot be used as variables (TRUE, FALSE, NULL, if…)

1.4.2 Type of Data in R

Basic data types in R can be divided into the following types:

numeric - (10.5, 55, 787)

integer - (1L, 55L, 100L, where the letter “L” declares this as an integer)

complex - (9 + 3i, where “i” is the imaginary part)

character (a.k.a. string) - (“k”, “R is exciting”, “FALSE”, “11.5”)

logical (a.k.a. boolean) - (TRUE or FALSE)

We can use the class() function to check the data type of a variable:

# numeric
x <- 10.5
class(x)
## [1] "numeric"
# integer
x <- 1000L
class(x)
## [1] "integer"
# complex
x <- 9i + 3
class(x)
## [1] "complex"
# character/string
x <- "R is exciting"
class(x)
## [1] "character"
# logical/boolean
x <- TRUE
class(x)
## [1] "logical"