Difference between revisions of "R/C2/Introduction-to-R-script/English"

Opening slide

Objectives

• How to work with an R script in RStudio

Pre-requisites

• R and RStudio
• Basic commands of R

If not, please locate the relevant tutorials on R on this website.

Systems requirements

• Ubuntu Linux OS 16.04
• R version 3.2.3
• RStudio version 1.1.456

Install R version 3.2.0 or higher.

What is R script

• An R script is a plain text file in which you save your R code
• Script allows you to show your work to others, and also reproduce and modify the results

Creating a folder for our project

• Before you begin please create a folder named myProject on Desktop.
• I have already created this folder on my Desktop.
• I shall now save all my scripts and data sets in this folder.
• Later, I shall set this folder as my Working Directory.

RStudio window

Highlight the tabs Untitled1 and R packages available in the Source window

Click on the small cross symbol next to these tabs.

Click on the green plus sign >> select R Script from the dropdown

• In the top left corner of RStudio, click on the green plus sign.
• Now from the dropdown menu, select R Script.

You can also create a new R script by pressing Ctrl+Shift+N together.

In the top left corner of the screen, click on the File option.

I am saving the script in the folder myProject on my Desktop, with the name myfirstscript.

Finally, click on the Save button.

RStudio automatically adds dot R at the end of the filename.

testSample <- c(1,2,3,4)

We have already learned how to create vectors earlier in this series.

In the Source window, type testSample space less than symbol.Now type hyphen space c 1 comma 2 comma 3 comma 4 in parentheses.

Press Enter.

Or, press Ctrl+S together to save the file.

print(testSample)

In the Source window, type p r i

Highlight Source button in the Source window

Highlight the output in Console window

You can see the line-by-line execution of the script in the Console.

You can also run the script by pressing Ctrl+Shift+Enter together.

For this, you need to first click in the script window.

firstVar = 10

Type firstVar with capital V space equal sign space 10 and press Enter.

print(firstVar)

In the Source window, type print.

I am typing only p r i n but the options appear and I select print from there. Now in parentheses, start typing firstVar.

RStudio shows firstVar; press Enter to select it.

Press Enter to go to the next line.

secondVar = 15

print(secondVar)

In the Source window, type secondVar space equal sign space 15 and press Enter.

Now, as shown before, type print secondVar in parentheses to show its value and press Enter .

# Creating an R script

Highlight the comment line and first line of code

R interprets each line of code.

Please make sure that your comment and the first line of code appear in separate lines.

To do that, first click on this line.

Comment/Uncomment Lines

From the dropdown menu, click on the Comment/Uncomment Lines option.

This option helps us to comment as well as uncomment a line.

Delete # hash symbol at the beginning of this line.

Or, you can press Ctrl+Z to uncomment this line.

Click on the Source button

In the top right corner of the Source window, click on the Source button.

The values of two variables, 10 and 15 are printed.

Highlighting the block of code

The output shows the values of two variables, 10 and 15 only.

Creating an R script using Ctrl+Shift+N

Use Ctrl+Shift+N to open a new script.

Save this script in the same folder myProject with the name mysecondscript.

Source

source('~/Desktop/myProject/myfirstscript.R', echo=TRUE).

In the Source window, type print and then the following words in parentheses.

In double quotes, Script space loaded.

Press Enter.

Summary

• How to create, save and run an R script

Assignment

• Create a script and save it on Desktop as testscript.R
• Load myfirstscript.R in this script and run it.

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Acknowledgement

Thank You

This is Sudhakar Kumar from IIT Bombay signing off. Thanks for watching.