Introduction to R

An Introduction to R Language

R language is an integrated suite for software facilities for data manipulation, calculation and graphical display.It can effectively handle data and also provide effective storage facility.R is very much a vehicle for newly developing methods of interactive data analysis. It has developed rapidly and has beeb extended by a large collection of packages.R can be regarded as an implementation of S language which was developed at Bell Laboratories by Ruck Becker, John Chambers and ALlen Wilks and also forms the basis of the S-PLUS systems.

R and Statistics

• Many people using R as a statisitics system. It is basically an environment within which many classical and modern statistical techniques has been implemented.
  • Some of them are built into the R base environment,but most of them are supplied as packages.
  • About 25 packages are supplied with R as standard and recommended packages.
  • Many more packages are available through the CRAN family of Internet Sites CRAN Packages

Many classical statistics and latest methodologies are available in R, bbut user always needs to prepare to do a little work to find it.As compared to other Statistical languages, R will give minimal output and store the results in a fit object for subsequent interrogation by further R functions.

Using R Interactively

• It always issue a prompt when it expects an input commands.
• The default prompt is “>” which is similar to UNIX and so it may appear that nothing is happening.

in using R under UNIX the suggested procedure for the first occasion is :

Create a sub-directory, say work by running the following few commads in terminal

  > mkdir work

make this directory a working directory

  > cd work

Start the R program with the command

 > R

To quit the R program, use

 > q()

Getting help with funtions and features

For getting help simply wirte help() in R console.

  > help()

For getting help about a specific topic write help(topic_name)

  > help(solve)

For getting help about features specified by special characters

 > help("[[")

For getting help in HTML format write

 > help.start()

R commands and case sensitivity

• R is an expression language with a very simple syntax.
• It is a case sensitive language which means “IS” and “is” are to different elements.
• R names can have aphanumeric symbols. And names are effectively unlimited in length.

Elementary Commands

• These are either expressions or assignments
• Expressions is given as a command,
  • it is evaluated,
  • Printed,
  • And the value is lost.
• Assignments also evaluates as an expression and passes the values to a variable but the result is not automatically printed.
• Commands are separated either by semi-colon(;) or by a newline.
• These commands can be grouped into compound experssions by usinf braces(‘{}’)
• Comments can be put almost everywhere by starting with a hashmark(‘#’).

Executing commands from diverting output to a file

• if commands are stored in external file, in the working directory you can use those commands using funtion source

 > source(filename.r)

• Window Source is also available in file menu.The function sink

  > sink("record.lis") # will store the output from console to external file
  > sink() # will restores the console once again.

Data Permanency and removing objects

Entities that are created in R are known as objects.These may be variables, arrays of numbers, character stings, functions or more general structure built from such components.During a R session, objects are created and stored by names and the R command

  > objects()
  # to display the name of the objects use
  > ls()

The collection of objects currently stored is called a workspace.

• To remove objects the function is rm:

  > rm(object_name)

Some Common and Important Commands

For installing packages

 > install.packages("package_name") 

For updating a particular package

  update.packages("package_name") 

Getting list of previously installed packages

  > old.packages() 

Unload package

 > detach("packagename") 

Uninstall a package

 > remove.packages("packagename")

Check R Language Version

 > version()

Check working Directory for storing R files

 > getwd()

Checking Available Directories in Working directory

 > dir()

Checking of available code files in R workspace

  > ls()