R is a open source statistical software. R software can be downloaded from the following link . https://www.r-project.org/
There are few GUI available for R software

1. R-Studio
2. Deducer
3. R-Commandar

Starting the R environment (This page uses the R-Studio GUI for examples )
Please double click the the R-Studio icon and the following window opens

The left top most window is called 'source' where the r codes are usually written and left bottom window is the R-Console
where the codes are executed. Press the run button in the source window to run the code

Basic Concepts

1. Package and Library
    R software uses the concept called packages for various operations which needs to be downloaded and installed in the space
    called R Library. To use the package, type the following syntax and press run
    library
   
2. Frequently used packages
    The following are the frequently used packages

S.No	Package	Type	remarks
1	stat	Basic Statistical function	Builtin
2	Randomforest	Classification and regression
3	foreign	Data Connection	Read and write data from other packages such as SPSS and SAS
4	XL connect	Data Connection	Read and write data from excel
5	RODBC	Data Connection	Connect to a database through ODBC
6	xtable	Data Handling
7	hmisc	Data Handling
8	rcurl	Data Handling
9	plyr	Data Handling
10	pastecs	Descriptive Statistics	Display summary statistics
11	ggplot2	Graphical display	Graphical display of data
12	lattice	Graphical Display	Graphical display of data
13	mlogit	Logit Model	Maximum Likelihood
14	nlme	Mixed Effects Model	Linear and Nonlinear
15	lme4	Mixed Effects Model	Linear and Generalized S4 models
16	caret	Predictive Modeling	Predictive Modeling
17	xml	Reading and creating xml and html files
18	Design	Regression
19	Survey	Survey
20	Survival	Survival Analysis	Survival Analysis
21	tm	Text Mining	Text Mining package

3. Data in R

    Data is stored and represented as vector in R software. The function "c" can be used to store the data as vector.
For example if want to store the age of 5 patients 
> age = c(50,45,30,41,24)          # R code

Here the age will be stored as vector age[].
> [1] 5  # R output
Age of first patient can be obtained by specifying the vector element age[1]. 

We can also use the following function to store data
1. Data entry through key in
    age = scan()
# R code 2. Entry through data editor
    age = c(0)   # R code initial value of  age to be changed in the editor
    Data.entry(age)  # R code
 
4. Basic Functions on Data

We can apply basic function on our data
>max(age)                  # R code maximum
>min(age)                  # R code minimum
>mean(age)               # R code mean
>sd(age)               # R code mean
>median(age)            # R code median
>table(age)              # R code frequency table
>summar(age)        # R code to list summary - mean,max,min,median,1st quartile, 3quartile