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R ggplot2 Boxplot

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The R ggplot2 boxplot is useful to graphically visualizing the numeric data, group by specific data. In this article we will show you, How to Create a ggplot boxplot, Format the colors, changing labels, drawing horizontal boxplots, and plot multiple boxplots using R ggplot2 with an example.

For this, we will use two data sets provided by the R, and they are: ChickWeight and diamonds data set

TIP: ggplot2 package is not installed by default. Please refer Install R Packages article to understand the steps involved in installing a package.

Create R ggplot2 Boxplot

In this example, we will show you, How to create a Boxplot using the ggplot2 package, and for this, we are going to use the ChickWeight data set, provided by the R Studio.

NOTE: If your requirement is to import data from external files then please refer R Read CSV article to understand the steps involved in CSV file import

R CODE

# Create a R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(ChickWeight, aes(x = Diet, y = weight)) + 
  geom_boxplot()

OUTPUT

R ggplot2 Boxplot 1

Change Colors of a Boxplot in R

In this example, we will show you, How to change the Boxplot box colours using fill argument

  • fill: Please specify the colour you want to use for your Boxplot. Type colors() in your console to get the list of colours available in R programming

R CODE

# Add Color to R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(diamonds, aes(x = cut, y = price)) + 
  geom_boxplot(fill = "midnightblue")

OUTPUT

R ggplot2 Boxplot 2

Change Colors of a Boxplot in R example 2

In this example, we will show you, How to change the Boxplot box colors using column data. Here, we are using the cut column data to differentiate the colors

R CODE

# Add Color to R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(diamonds, aes(x = cut, y = price, fill = cut)) + 
  geom_boxplot(outlier.colour="black", outlier.shape=16, outlier.size=2)

OUTPUT

R ggplot2 Boxplot 3

Change Outliners of R ggplot2 Boxplot

In this example we will show you, How to change the boxplot outliners colors using the following arguments

  • outlier.color: Please specify the color you want to use for your outliner. Type colors() in your console to get the list of colors available in R programming
  • outlier.shape: Please specify the shape you want to use for the outliner.
  • outlier.size: Specify the size of the outliner.

R CODE

# Change Outliers in a R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(diamonds, aes(x = cut, y = price, fill = cut)) + 
  geom_boxplot(outlier.color = "seagreen", outlier.shape = 8, outlier.size = 2)

OUTPUT

R ggplot2 Boxplot 4

Add Mean to R ggplot2 Boxplot

In this example, we will show you, How to add Mean value to boxplot using the stat_summary argument

R CODE

# Adding Mean to a R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(diamonds, aes(x = cut, y = price, fill = cut)) + 
  geom_boxplot() +
  stat_summary(fun.y = "mean", geom = "point", shape = 8, size = 2, color = "white")

OUTPUT

R ggplot2 Boxplot 5

Alter Legend position of an R ggplot2 Boxplot

By default, ggplot will position the legend at the right side of a Boxplot. In this example, we will show you, How to change the legend position from right to top. Note, You can use legend.position = “none” to completely remove the legend.

R CODE

# Alter lengend Position in a a R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(diamonds, aes(x = cut, y = price, fill = cut)) + 
  geom_boxplot() +
  theme(legend.position = "top")

OUTPUT

R ggplot2 Boxplot 6

Notch argument in R Boxplot

In this example we will show you, How to draw a line on each side of the boxes using notch argument

  • notch: It is a Boolean argument. If it is TRUE, a notch is drawn on each side of the box.

TIP: If the notches of 2 plots are overlapped then, we can say that the medians of them are same otherwise, they are different.

R CODE

# Notch argument in R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(ChickWeight, aes(x = Diet, y = weight)) + 
  geom_boxplot(fill = "chocolate", notch = TRUE)

OUTPUT

R ggplot2 Boxplot 7

Horizontal ggplot Boxplot in R

In this example, we will show you, How to change the default vertical boxplot into horizontal box plot using coord_flip() function

R CODE

# Create Horizontal R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot
ggplot(ChickWeight, aes(x = Diet, y = weight)) + 
  geom_boxplot() +
  coord_flip()

OUTPUT

R ggplot2 Boxplot 8

Multiple ggplot Boxplot in R

In this example, we will show you, How to group multiple boxplots

R CODE

# Multiple R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot Importing
ggplot(diamonds, aes(x = cut, y = price, fill = clarity)) + 
  geom_boxplot()

OUTPUT

R ggplot2 Boxplot 9

How to use Facets in R ggplot2 Boxplot

This example we will show you, How to draw multiple boxplots, by dividing the data based on a column value. Here, we are using the clarity column data to divide the boxplots

R CODE

# Use Facet in R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot Importing
ggplot(diamonds, aes(x = cut, y = price, fill = clarity)) + 
  geom_boxplot() +
  facet_wrap(~ clarity)

OUTPUT

R ggplot2 Boxplot 10

How to use Facets in R ggplot2 Boxplot example 2

By default facet_wrap() will assign the same y-axis to all the boxplot but, you can change it (giving independent axis) to each and every boxplot by adding one more attribute called scale.

R CODE

# Use Facet in R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot Importing
ggplot(diamonds, aes(x = cut, y = price, fill = clarity)) + 
  geom_boxplot() +
  facet_wrap(~ clarity, scale = "free")

OUTPUT

R ggplot2 Boxplot 11

Assigning names to R ggplot Boxplot

In this example, we will show you, How to assign names to ggplot boxplot, X-Axis, and Y-Axis using labs function

R CODE

# Add Labels to R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot Importing
ggplot(diamonds, aes(x = cut, y = price, fill = cut)) + 
  geom_boxplot() +
  labs(title="GGPLOT BOXPLOT", x="Price in Dollars", y="Cut")

OUTPUT

R ggplot2 Boxplot 12

Change R ggplot2 boxplot Theme

In this example, we will show you, How to change the default theme of a ggplot boxplot

  • theme_dark(): We are using this function to change the boxplot default theme to dark. Type theme_ then R Studio intelligence will show you the list of available options. For example, theme_grey()

R CODE

# Change themeof a R ggplot boxplot

# Importing the ggplot2 library
library(ggplot2)

# Create a Boxplot Importing
ggplot(diamonds, aes(x = cut, y = price, fill = cut)) + 
  geom_boxplot() +
  labs(title="GGPLOT BOXPLOT", x="Price in Dollars", y="Cut") +
  theme_dark()

OUTPUT

R ggplot2 Boxplot 13

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