Cleveland Dot Plots or Dumbell Plots

cleveland.R

## Cleveland Dot Plots or Dumbell Plots
## This gist notes some approaches for drawing Cleveland dot plots or dumbell plots in `ggplot`

library(tidyverse)

n = 10
dataf = tibble(x = rep(1:n, 2),
               category = c(rep('A', n), rep('B', n)),
               value = x + 2*(category == 'B'))

## Line segments w/o arrows are pretty easy
ggplot(dataf, aes(x, value, color = category)) +
    stat_summary(color = 'black', 
                 fun.ymin = min, fun.ymax = max,
                 geom = 'linerange') +
    geom_point()

## Even easier using geom_line()
ggplot(dataf, aes(x, value, color = category)) +
    geom_line(aes(group = x), color = 'black') +
    geom_point()

## Say we want arrows from A to B, eg, to show change between two points in time or between a sample and subsample
ggplot(dataf, aes(x, value, color = category)) +
    geom_line(aes(group = x), color = 'black', 
              arrow = arrow()) +
    geom_point()

## Arrow direction doesn't follow the order of the levels in `category`? 
ggplot(dataf, aes(x, value, color = fct_rev(category))) +
    geom_line(aes(group = x), color = 'black', 
              arrow = arrow()) +
    geom_point()

## Just change where arrow() places the ends
ggplot(dataf, aes(x, value, color = category)) +
    geom_line(aes(group = x), color = 'black', 
              arrow = arrow(ends = 'first')) +
    geom_point()

## geom_segment() + spread() is another approach
ggplot(dataf, aes(x, value, color = category)) +
    geom_segment(data = spread(dataf, key = category, value = value), 
                 aes(xend = x, y = A, yend = B), color = 'black', 
                 arrow = arrow()) +
    geom_point()