Definition

A donut plot is a pie chart with a hole in the center. It’s a way to show the distribution of a categorical variable, but it can be a little bit tricky to read. It’s not recommended to use it if you have a large number of categories.

It’s similar to a pie chart, but it’s easier to compare the size of the slices. It’s also possible to add a number inside each slice to show the exact proportion.

# load library
library(ggplot2)

# Create test data.
data <- data.frame(
  category=c("A", "B", "C"),
  count=c(10, 60, 30)
)

# Compute percentages
data$fraction <- data$count / sum(data$count)

# Compute the cumulative percentages (top of each rectangle)
data$ymax <- cumsum(data$fraction)

# Compute the bottom of each rectangle
data$ymin <- c(0, head(data$ymax, n=-1))

# Compute label position
data$labelPosition <- (data$ymax + data$ymin) / 2

# Compute a good label
data$label <- paste0(data$category, "\n value: ", data$count)

# Make the plot
ggplot(data, aes(ymax=ymax, ymin=ymin, xmax=4, xmin=3, fill=category)) +
  geom_rect() +
  geom_label( x=3.5, aes(y=labelPosition, label=label), size=6) +
  scale_fill_brewer(palette=4) +
  coord_polar(theta="y") +
  xlim(c(2, 4)) +
  theme_void() +
  theme(legend.position = "none")

What for?

Donut plots are used to visualize the distribution of categorical data. They are particularly useful when you want to highlight the proportions of different categories within a dataset. The central hole of the donut plot can be used to display additional information, such as total values or percentages, making it easier to interpret the data at a glance.

Compared to pie charts, donut plots provide a more effective visual comparison of category sizes due to the space in the center, which allows for a better understanding of the proportions. However, they are best suited for datasets with a limited number of categories, as too many slices can make the plot difficult to read.

Key purposes of using a donut plot include:

• Highlighting the proportional distribution of categories within a dataset.
• Comparing the relative sizes of different categories.
• Displaying additional information in the center of the plot for enhanced data interpretation.
• Providing a visually appealing alternative to pie charts for presentations and reports.

Variation

The donut plot is a variation of different charts. Here are some examples:

• Pie chart: The most basic form of a donut plot. It’s a circle divided into slices to illustrate numerical proportions.
• Bar chart: A bar chart is a chart with rectangular bars with lengths proportional to the values they represent.

Related

Lollipop plot

A fancy barplot where bars are replaced with a dot and a segment. Try it and adopt it.

Pie chart

A circular statistical graphic, which is divided into slices to illustrate numerical proportions.

Barplot

A chart with rectangular bars with lengths proportional to the values they represent. Use it to compare values.

Boxplot

Summarize the distribution of several numeric variables using boxes. Use it if you have a limited dataset size.

Build your own

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