How do I use color in a geom_dotplot?

Question

I have this dotplot:

ggplot(mpg, aes(drv, hwy)) +
  geom_dotplot(binwidth = 1, binaxis = 'y', stackdir = 'center')

which renders as

I want to color the dots by manufacturer. If I add a fill aesthetic:

ggplot(mpg, aes(drv, hwy, fill = manufacturer)) +
  geom_dotplot(binwidth = 1, binaxis = 'y', stackdir = 'center')

it renders as

It looks like adding color has defeated the stacking algorithm somehow, causing the dots to overlap. How do I fix this?

Answer 1

Using geom_beeswarm from package ggbeeswarm is an option. It doesn't center the even numbered rows of dots quite the same way, but the point color seems to work out better than geom_dotplot.

library(ggbeeswarm)

ggplot(mpg, aes(drv, hwy, color = manufacturer)) +
     geom_beeswarm(size = 2)

Answer 2

This is the closest I've gotten:

ggplot(mpg, aes(drv, hwy, fill = manufacturer)) +
  geom_dotplot(stackdir = "centerwhole",stackgroups = TRUE,
  binpositions = "all", binaxis = "y", binwidth = 1)+
  theme_bw()

If you need everything to be perfectly centered, I'd review this example of writing a for loop to plot three separate charts (one for each factor level), using a shared legend.

Edit:

And here's the chart following the linked process of using a function to combine three plots with the same legend: