Mosaic Plots

Mosaic plots are used to display the distribution of two categorical variables. These plots look very similar to a stacked side-by-side bar chart.

Mosaic Plot

The example below uses the ggplot2, ggmosaic and the dplyr packages to construct a mosaic plot of automobile class and drive train for dat stored in the mpg dataset.

library(ggplot2) # Loads the ggplot2 library
library(ggmosaic) # Loads the mosaic plot library
library(dplyr) # loads the dplyr library for cleaning data

The plot below displays the distribution of drive train within each level of automobile class. The width of each bar is determined by the number of observations within each level of class.

 mpg %>% 
  count(class, drv) %>% # creates a frequency table
  ggplot() + 
    geom_mosaic(aes(x = product(class), fill = drv, weight = n)) +
    labs(
      title = "Drive Train within Automobile Class",
      x = "Gear", 
      y = ""
      ) 

It is easy to see that the mpg data set contains very few cars that are 2 seaters.

Mathematicss, Computer Science, and Statistics Department Gustavus Adolphus College