ggplot dotplot: What is the proper use of geom_dotplot?

Question

My purpose is to reproduce this figure [ref] with ggplot2 (author: Hadley Wickham).

Here is my effort based on geom_point and some ugl

Answer 1

Coincidentally, I've also spent the past day fighting with geom_dotplot() and trying to make it show a count. I haven't figured out a way to make the y axis show actual numbers, but I have found a way to truncate the y axis. As you mentioned, coord_cartesian() and limits don't work, but coord_fixed() does, since it enforces a ratio of x:y units:

library(tidyverse)
df <- structure(list(x = c(79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105), y = c(1, 0, 0, 2, 1, 2, 7, 3, 7, 9, 11, 12, 15, 8, 10, 13, 11, 8, 9, 2, 3, 2, 1, 3, 0, 1, 1)), class = "data.frame", row.names = c(NA, -27L))
df <- tidyr::uncount(df, y) 

ggplot(df, aes(x)) +
  geom_dotplot(method = 'histodot', binwidth = 1) +
  scale_y_continuous(NULL, breaks = NULL) + 
  # Make this as high as the tallest column
  coord_fixed(ratio = 15)

Using 15 as the ratio here works because the x-axis is also in the same units (i.e. single integers). If the x-axis is a percentage or log dollars or date or whatever, you have to tinker with the ratio until the y-axis is truncated enough.

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Edited with method for combining plots

As I mentioned in a comment below, using patchwork to combine plots with coord_fixed() doesn't work well. However, if you manually set the heights (or widths) of the combined plots to the same values as the ratio in coord_fixed() and ensure that each plot has the same x axis, you can get psuedo-faceted plots

# Make a subset of df
df2 <- df %>% slice(1:25)

plot1 <- ggplot(df, aes(x)) +
  geom_dotplot(method = 'histodot', binwidth = 1) +
  scale_y_continuous(NULL, breaks = NULL) + 
  # Make this as high as the tallest column
  # Make xlim the same on both plots
  coord_fixed(ratio = 15, xlim = c(75, 110))

plot2 <- ggplot(df2, aes(x)) +
  geom_dotplot(method = 'histodot', binwidth = 1) +
  scale_y_continuous(NULL, breaks = NULL) + 
  coord_fixed(ratio = 7, xlim = c(75, 110))

# Combine both plots in a single column, with each sized incorrectly
library(patchwork)
plot1 + plot2 +
  plot_layout(ncol = 1)

# Combine both plots in a single column, with each sized appropriately
library(patchwork)
plot1 + plot2 +
  plot_layout(ncol = 1, heights = c(15, 7) / (15 + 7))