# R - Boxplots

Boxplots are created in R by using the

**boxplot()**function.

## Syntax

The basic syntax to create a boxplot in R is −boxplot(x, data, notch, varwidth, names, main)Following is the description of the parameters used −

**x**is a vector or a formula.**data**is the data frame.**notch**is a logical value. Set as TRUE to draw a notch.**varwidth**is a logical value. Set as true to draw width of the box proportionate to the sample size.**names**are the group labels which will be printed under each boxplot.**main**is used to give a title to the graph.

## Example

We use the data set "mtcars" available in the R environment to create a basic boxplot. Let's look at the columns "mpg" and "cyl" in mtcars.input <- mtcars[,c('mpg','cyl')] print(head(input))When we execute above code, it produces following result −

mpg cyl Mazda RX4 21.0 6 Mazda RX4 Wag 21.0 6 Datsun 710 22.8 4 Hornet 4 Drive 21.4 6 Hornet Sportabout 18.7 8 Valiant 18.1 6

## Creating the Boxplot

The below script will create a boxplot graph for the relation between mpg (miles per gallon) and cyl (number of cylinders).# Give the chart file a name. png(file = "boxplot.png") # Plot the chart. boxplot(mpg ~ cyl, data = mtcars, xlab = "Number of Cylinders", ylab = "Miles Per Gallon", main = "Mileage Data") # Save the file. dev.off()When we execute the above code, it produces the following result −

## Boxplot with Notch

We can draw boxplot with notch to find out how the medians of different data groups match with each other.The below script will create a boxplot graph with notch for each of the data group.

# Give the chart file a name. png(file = "boxplot_with_notch.png") # Plot the chart. boxplot(mpg ~ cyl, data = mtcars, xlab = "Number of Cylinders", ylab = "Miles Per Gallon", main = "Mileage Data", notch = TRUE, varwidth = TRUE, col = c("green","yellow","purple"), names = c("High","Medium","Low") ) # Save the file. dev.off()When we execute the above code, it produces the following result −

*Table of contents:*1. R - Overview

2. R - Environment Setup

3. R - Basic Syntax

4. R - Data Types

5. R - Variables

6. R - Operators

7. R - Decision Making

8. R - Loops

9. R - Functions

10. R - Strings

11. R - Vectors

12. R - Matrices

13. R - Arrays

14. R - Factors

15. R - Data Frames

16. R - Packages

17. R - Data Reshaping

18. R - CSV Files

19. R - Excel Files

20. R - Binary Files

21. R - XML Files

22. R - JSON Files

23. R - Web Data

24. R - Database

25. R - Pie Charts

26. R - Bar Charts

27. R - Boxplots

28. R - Histograms

29. R - Line Graphs

30. R - Scatterplots

31. R - Mean, Median and Mode

32. R - Linear Regression

33. R - Multiple Regression

34. R - Logistic Regression

35. R - Normal Distribution

36. R - Binomial Distribution

37. R - Poisson Regression

38. R - Analysis of Covariance

39. R - Time Series Analysis

40. R - Nonlinear Least Square

41. R - Decision Tree

42. R - Random Forest

43. R - Survival Analysis

44. R - Chi Square Tests

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