Boxplot Function in R: How To Create a Boxplot

This article will demonstrate how to use the boxplot function in R to create boxplots. And it is a fundamental graph that is usually used in data analytics. So, follow below to learn how to use this function.

What is the boxplot in R?

In R, the boxplot function creates a boxplot to display the distribution of a continuous or categorical variable. The boxplots consist of a summary of the data set containing the minimum, first quartile, median, third quartile, and maximum.

And here, we will learn about the syntax of this function.

Boxplot Function in R: The Syntax

boxplot(x, data, names, main, col)

Parameters

• x: a formula or a vector of values or a matrix.
• data:  a dataframe, a list, or an environment (or an object that can be coerced to one of these).
• names: a character vector giving the names of the plots.
• col: a vector of colors to be used for the boxes in the plot.

How to use the boxplot function in R?

Create a basic boxplot

First, we will create data to create a boxplot as follows:

# Create a data
set.seed(100)
x <- rnorm(500)

# View six elements in the data
head(x)

Output

[1] -0.50219235  0.13153117 -0.07891709  0.88678481  0.11697127  0.31863009

We will apply the boxplot function above to create a boxplot with this data. See the code example below

# Create a data
set.seed(100)
x <- rnorm(500)

# Create a boxplot
boxplot(x)

Output

The col argument in the boxplot function can be used to fill the boxes in the plot with a specific color. For example:

# Create a data
set.seed(100)
x <- rnorm(500)

# Create a boxplot
boxplot(x, col = 'green')

Output

You can also change the border color of the entire boxplot and add the title and names of the x-axis and y-axis in this graph. Check out the code example below:

# Create a data
set.seed(100)
x <- rnorm(500)

# Create a boxplot
boxplot(x,
    col = "green",
    border = 2, main = "The boxplot",
    xlab = "X-axis", ylab = "Y-axis"
)

Output

Create multiple boxplots

To create multiple boxplots in R, you can pass multiple vectors or formulas to the boxplot() function. For example:

# Create a data
set.seed(100)
data1 <- rnorm(300)
data2 <- rnorm(100)
data3 <- rnorm(500)

# Create multiple boxplots
boxplot(data1, data2, data3)

Output

Similarly, we can customize this graph as follows:

# Create a data
set.seed(100)
data1 <- rnorm(300)
data2 <- rnorm(100)
data3 <- rnorm(500)

# Create multiple boxplots
boxplot(data1, data2, data3,
    main = "The multiple boxplot",
    xlab = "X-axis", ylab = "Y-axis",
    col = c("green", "red", "blue")
)

Output

Summary

To summarize, the boxplot() function in R is used to create a box plot, a graphical representation of the distribution of a continuous or categorical variable. We hope this article is helpful for your work and you can understand by using this function. 

If you have any questions, don’t hesitate to comment below. 

Have a great day!

Scott Miller

Hi, guys! My name’s Scott Miller. My current job is a software developer and I have shared a lot of quality articles about Javascript, C, C++, C#, Python, PHP, R, Java programming languages. I’m hoping they can assist you.

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