Off-set points in a diagonal line - similar and geom_jitter

Question

How can I offset points along a diagonal line with a categorical x variable?

Is there something similar to position_jitter to achieve this?

ggplot(mpg, aes(cyl, hwy)) + geom_point(position = position_jitter(width = 0.2))

In this example, the highest hwy value for each cyl should be at the top-left of that category and the lowest hwy value at the bottom-right.

Answer 1

Here's a mildly hacky solution:

library(tidyverse)

p1 <- ggplot(mpg, aes(cyl, hwy)) + geom_point()

diagonal_plot <- function(.plot) {
  p <- ggplot_build(.plot)
    p$data[[1]] <- 
       p$data[[1]] %>% 
       group_by(x) %>% 
       mutate(order_y = as.integer(factor(y))) %>% 
# making helper column for ranks depending on height of y
       ungroup %>% 
       mutate(x = x - order_y/100) %>% 
#this one was just an idea to create the offset to x depending on the rank of y
       select(-order_y)

plot(ggplot_gtable(p))

}

diagonal_plot(p1)

Created on 2018-12-27 by the reprex package (v0.2.0).