Introduction and Installation of R

R is:

• A programing language developed at AT&T Bell Laboratories by Robert Gentleman and Ross Ihaka
• An alternative to S language
• A free, open source language, with highly active community members
• Available across all platforms (Linux, Mac, Windows)
• The RStudio program can run on a desktop or through a web browser.

Due to its underlying philosophy and design; R is useful for statistical computation and graphic visualization. R has a worldwide repository system—Comprehensive R Archive Network (CRAN). It can be accessed at http://cran.r-project.org. As of 2011, there were more than 3,000 such packages hosted on CRAN and many more on other websites.

You can install R from the following two sources:
CRAN Website: http://cran.r-project.org/
RStudio: https://www.rstudio.com/products/rstudio/download/

R Installation: 
First, you will learn how to install R on Windows from the CRAN website. You can download the package from: https://cran.r-project.org/bin/windows/base/.

1. Download R 3.X.X for Windows executable file (.exe).
2. Click “Next” in the Setup Wizard. (You may leave the setting as default.)
3. Finally, open R console (RGUI from your desktop).

Now, you will learn how to install R on Windows from the RStudio website.

1. Download RStudio from https://www.rstudio.com/products/rstudio/download/.
2. Run the installation file.
3. Open RStudio.

The different areas of RStudio are depicted below:

In RStudio, you can set the workspace by clicking Tools -> Global Options.

• getwd() -return working directory
• setwd() -set working directory

Many data scientist programmers and statisticians use R to design tools for analyzing data and to contribute their codes as pre-assembled collections of functions and objects called packages. You can install an R package by clicking GUI RStudio ->Tools -> Install Packages or directly from packages tab in File/Package Panel

Getting Started : Quick Tour!!

R has many operators to perform different mathematical and logical operations. These can be categorized as follows:
Arithmetic Operators: used for mathematical operations like addition and multiplication, look at the table below:

Operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division
^	Exponent
%%	Modulus
%/%	Integer Division

Logical Operators: These operators are used to perform Boolean operations such as “AND” and “OR.”, look at the table below:

Operator	Description
!	Logical NOT
&	Element-wise logical AND
&&	Logical AND
|	Element-wise logical OR
||	Logical OR

Relational Operators: used to compare two values, look at the table below:

Operator	Description
<	Less than
>	Greater than
<=	Less than or equal to
>=	Greater than or equal to
==	Equal to
!=	Not equal to

Assignment Operator: These operators are used to assign values to variables. Variables are assigned using “<-”, although “=” also works.

Lets do a simply hello world program and execute as below.