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Pie-Donut Chart in R

In this R tutorial, you are going to learn how to combine a PieDonut Chart. In PieDonut Chart, the response is the frequency of observations that are classified into the categories of two explanatory variables.

If you prefer a video-tutorial, you can watch the tutorial at the YouTube channel.

We are going to use the Titanic data set available in the R data sets library. It presents the data on the survival of passengers on the Titanic and we are going to classify it by the class.

Before starting the plot, let’s load the necessary packages. We are going to use the webr package to build the Pie-Donut chart. This library runs on the ggplot2 package, and we will also need the dplyr package for creating a table with the summarised data for the plot.

# loading the appropriate libraries
library(ggplot2)
library(webr)
library(dplyr)


The next step is to load the dataset

# loading the dataset
data <- as.data.frame(Titanic)
head(data)
##   Class    Sex   Age Survived Freq
## 1   1st   Male Child       No    0
## 2   2nd   Male Child       No    0
## 3   3rd   Male Child       No   35
## 4  Crew   Male Child       No    0
## 5   1st Female Child       No    0
## 6   2nd Female Child       No    0
tail(data)
##    Class    Sex   Age Survived Freq
## 27   3rd   Male Adult      Yes   75
## 28  Crew   Male Adult      Yes  192
## 29   1st Female Adult      Yes  140
## 30   2nd Female Adult      Yes   80
## 31   3rd Female Adult      Yes   76
## 32  Crew Female Adult      Yes   20

The dataset presents the information on the Class, Sex, Age, Survived (Yes or No) and the frequency of the observations.

We are going to plot the information on Survived (Yes or No) in each Class. Thus, the first step is to build a table with the data.

# Building a table with the data for the plot
PD = data %>% group_by(Class, Survived) %>% summarise(n = sum(Freq))
print(PD)
## # A tibble: 8 x 3
## # Groups:   Class [4]
##   Class Survived     n
##   <fct> <fct>    <dbl>
## 1 1st   No         122
## 2 1st   Yes        203
## 3 2nd   No         167
## 4 2nd   Yes        118
## 5 3rd   No         528
## 6 3rd   Yes        178
## 7 Crew  No         673
## 8 Crew  Yes        212

Basic Pie-Donut chart

The Pie-Donut chart will be build using the function PieDonut() from the webr package.

The arguments are the dataset PD, the aesthetics aes() where we define the two categorical variables, Class and Survived, and the response count, n. We are also assigning a title to the chart.

# Pie-Donut chart
PieDonut(PD, aes(Class, Survived, count=n), title = "Titanic: Survival by Class")


The chart shows that 14.8% of the people were in the First Class, and 62.5% survived. In contrast, 40.2% of the people aboard were Crew, and only 24.0% survived. Similar readings can be done for second and third classes.

In this chart, the percentages of people who survived are presented in relation to the Class. Another way to show the data is with the portions of survived with regard to the total passengers.

We can do it by adding the argument ratioByGroup = FALSE.

# Pie-Donut chart
PieDonut(PD, aes(Class, Survived, count=n), title = "Titanic: Survival by Class",
         ratioByGroup = FALSE)

Now we can see the number of passengers from the First Class that survived corresponds to 9.22% of the total number of people aboard.

Another way of looking into the data is to change the pie and donut categories. In the following chart, the survival data is presented in the internal pie and the Class in the donut.

# Pie-Donut chart
PieDonut(PD, aes(Survived, Class, count=n), title = "Titanic: Survival by Class")

The chart shows that 68% of the passengers did not survive, from which 45.2% were from the Crew.


Exploding the pie

It is also possible to “explode” one or more categories. Let’s explode the Survived = Yes:

# Pie-Donut chart
PieDonut(PD, aes(Survived, Class, count=n), title = "Titanic: Survival by Class",
         explode = 2)

And it is also possible to explode the donut part of the chart:

# Pie-Donut chart
PieDonut(PD, aes(Survived, Class, count=n), title = "Titanic: Survival by Class",
         explode = 2, explodeDonut=TRUE)
## Warning: Ignoring unknown aesthetics: explode


Controlling the radius

Finally, let’s see how to control the radius of the pie and the donut with the arguments r0, r1 and r2. If not defined, the values are r0 = 0.3, r1 = 1. r2 = 1.2.

# Pie-Donut chart
PieDonut(PD, aes(Survived, Class, count=n), title = "Titanic: Survival by Class",
         r0 = 0)

PieDonut(PD, aes(Survived, Class, count=n), title = "Titanic: Survival by Class",
         r0 = 0.45, r1 = 0.9)


The charts above show how r0 and r1 arguments affect the radius the inner hole, the inner pie/donut width, and the outer donut width.

For information on the PieDonut() function, run ?PieDonut in your console window or go to https://cardiomoon.github.io/webr/reference/PieDonut.html

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