Alluvial plot in ggplot2 with ggalluvial

Package

Author

Cory Brunson

Sample data set

The vaccinations data set from the ggalluvial package contains a survey “that asked respondents their probability of vaccinating for influenza”. The response variable is the discretized probability of vaccinating, freq the number of respondents and survey the survey designation.

# install.packages("ggalluvial")
library(ggalluvial)

vaccinations

Alluvial plot

The ggalluvial package provides the geom_alluvium and geom_stratum functions to create alluvial diagrams in ggplot2. You will need to pass your data in long format, specify the axis variables inside aes and use the previous functions.

Note that you can also add the text for each stratum, add the names of the axis variables (in the following examples you won’t see them because we set theme_void) and change the ggplot2 theme, among other customizations.

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

Alluvial plot in ggplot2

If your data set contains more categorical variables you can pass them to aes (axis1, axis2, axis3 …) as shown in the example below.

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey,   # First variable on the X-axis
           axis2 = response, # Second variable on the X-axis
           axis3 = survey,   # Third variable on the X-axis
           y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

Alluvial plot in R with ggalluvial

Curve types

The type of flows of the plot area can be customized with the curve_type argument of the geom_alluvium function. The default value is "xspline", which produces approximation splines using four points per curve. The alternatives are listed below:

Lineal alluvial diagram in R

Linear

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response),
                curve_type = "linear") +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

Curve type of the alluvial plot

Cubic

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response),
                curve_type = "cubic") +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

geom_alluvium and geom_stratum functions in ggplot2

Quintic

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response),
                curve_type = "quintic") +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

Change the curve type in ggalluvial

Sine

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response),
                curve_type = "sine") +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

ggalluvial package in R

Arctangent

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response),
                curve_type = "arctangent") +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

Alluvial diagram in R

Sigmoid

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response),
                curve_type = "sigmoid") +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

Note that there is an additional argument named curve_range for alternative curve types based on asymptotic functions. Type geom_alluvium for additional details.

Color customization

It is possible to customize the colors of the flows. You can set a single color for them, use a predefined color palette or use your own vector of colors. Note that you can also modify the colors of the stratum boxes.

Fill color

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = "red")) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  scale_fill_viridis_d()
  theme_void()

Fill color of the alluvial plot

Color palette

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  scale_fill_viridis_d() +
  theme_void()

Change the color scale in ggalluvial

Custom colors

# install.packages("ggalluvial")
library(ggalluvial)

# Colors
colors <- hcl.colors(4, "Red-Blue")

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  scale_fill_manual(values = colors) +
  theme_void()

Custom flow colors of the alluvial plot

Stratum color

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum(aes(fill = response)) +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void()

Change the color of the stratums in ggalluvial

Legend customization

As the ggalluvial package was built with ggplot2 it is possible to customize the legend of the plots, such as changing its title, the key labels, its position or remove it as shown in the following examples

Change the title of the legend of the alluvial diagram

Legend title

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void() +
  guides(fill = guide_legend(title = "Title"))

Change the key legend labels with ggalluvial

Legend key labels

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void() +
  scale_fill_hue(labels = c("A", "B", "C", "D"))

Remove the legend of the alluvial plot in R

Remove the legend

# install.packages("ggalluvial")
library(ggalluvial)

ggplot(data = vaccinations,
       aes(axis1 = survey, axis2 = response, y = freq)) +
  geom_alluvium(aes(fill = response)) +
  geom_stratum() +
  geom_text(stat = "stratum",
            aes(label = after_stat(stratum))) +
  scale_x_discrete(limits = c("Survey", "Response"),
                   expand = c(0.15, 0.05)) +
  theme_void() + 
  theme(legend.position = "none")