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Basic R Tasks

Table of Contents

1. Introduction
2. Install R
3. R Help
4. Create New Vector
5. Print a Vector
6. Compute Mean of a Vector
7. Compute Quartiles of a Vector
8. Create Histogram
9. Create Boxplot
10. Redirect Output to File

1. Introduction

• R is a popular programming language used for data analysis and visualization.
• R was developed by Ross Ihaka and Robert Gentleman in 1993 to use for teaching statistics at the University of Aukland.
• R was inspired by the S programming language.
• R is open source, free software.

2. Install R

• Find the site for downloading R on Windows or on a Mac one of these search strings:
  

  download R for Windows
  download R for Mac
  

3. R Help

• To view the R help pages for R functions, use the help function, for example:
  

  > help("quantile")
  

4. Create New Vector

• To create a vector named v, use the c (combine) function:
  

  > v <- c(34, 29, 71, 49, 118)
  

  <- is the R assignment operator.

5. Print a Vector

• To print a vector in the R Console, either type the variable name on a line by itself or use the print function:
  

  > v
  [1] 34 29 71 49 118
  > print(v)
  [1] 34 29 71 49 118
  

6. Compute Mean of a Vector

• Compute the mean or average of the vector v:
  

  > mean(v)
  [1] 60.2
  

7. Compute Quartiles of a Vector

• Compute the first quartile of the vector v:
  

  > quartile(v, 0.25)
  25%
   34
  

• Compute the third quartile of the vector v:
  

  > quartile(v, 0.75)
  75%
   71
  

• Compute both the first and third quartiles of the vector v:
  

  > quartile(v, 0.75)
    25%  75%
     34   71
  

8. Create Histogram

• To create a histogram, use the hist function
  

  > hist(v)
  

  

9. Create Boxplot

• To create a boxplot, use the boxplot function
  

  > boxplot(v)
  

  

10. Redirect Graphical Output

• To redirect graphical output to a PNG image file:
  

  > # The lines that start with # are comment lines.
  > # The /it223 directory should already be created.
  >
  > # Set working directory to /it223 on the C drive.
  > setwd("C:/it223")
  >
  > # Send graphical output to PNG image file:
  > png("hist.png")
  >
  > # Create histogram, which goes to image file:
  > hist(v)
  >
  > # End redirection -- resume sending graphical
  > # output to R Console.
  > dev.off( )
  

  These additional functions are available for sending graphical output to other image file types:
  

  bmp  jpeg  tiff