Working with R:

R is a case-sensitive language. It distinguished between X and x . As X is capital letter while x is small letter.

We are writing program in Console window. Here , you are doing simple calculation as :

There is a disadvantage of R , we cannot save program codes in file . So , we can use more user friendly tool Rstudio for coding and storing programs.

Working with Rstudio :

When we open Rstudio , it looks like –

We have three windows :

First window shows Console . Here , we can write and execute programs simultaneously.

Second window is upper right. It shows Environment and History window.

Third window is lower right. It shows Files , Plots , Packages, Help and Viewer windows.

We open a new window , called Script window.

For opening a Script window, click on File tab on upper left corner of Rstudio . Then , click on New File and click on R Script. It will look like –

I am so excited to start my first program in Rstudio. First type help() and pres ctrl +R(control + R) to run program. You can also use ctrl+Enter to run the program.

help()

When we execute the code , it shows in console window to execute.

It will open Help window in bottom right window.

It helps us to find help in functions for programming.

Another code :-

help.start()

By running this code, it opens Help window .It shows introduction of R.

You can do simple calculation . Write this code in Script window –

1+1

Output will be shown in Console window:-

[1] 2

Similarly , you can do other calculations as-

2*5

Output –

[1]  10

Assignment Operator:

We have use assignment operator as “<-”  & “=” .

Objects :

It is used to store the values . We can create object by assigning values to object.

a<-1

In this program , we create an object named “a” , which store value 1.We are using assignment operator(<-) to assign value to object. We can see “a” object in Environment window. The object a stores 1.

Comments:

It is added to make program easier to understand . We can add comments by adding “#”. It is non-executable code ( it is not execute by R).

You can check out –

Here , # object  a creation is a comment . It gives explanation of our code.

Programming basic constraints :

We have two phases while running the program. It is compilation and execution.

Computer only reads binary form . When we run a program, first the program converts into machine understandable language in form of binary(0 or 1) source file. The process is called compilation.  After compilation , the binary file is loaded into computer memory for execution .

Every code written in script window is compile and execute . But comments are ignored in compilation and execution.

We can store an object like this also –

b<-1 + 1  

It will store 2.

To check “b” object value , we run this code-

b

It displays this output in console window –

[1] 2

We can remove objects from Environment window. We can do it by using rm() :-

rm(a)

You can checkout Environment window. There is no object “a” stored in it.

c()

We can combine multiple values in an object by using c() .

x<-c(1,2)

It creates x object , which stores 1 and 2.