Geom_Hex coloring by 3rd variable

Question

I'm trying to create a normal hexbin plot but instead of coloring the plot by count, the default, I would like to have it colored by the average value of a third variable. In my particular case, I cannot use the stat_summary_hex function.

library(ggplot2)
library(hexbin)

x <- rnorm(1e4, 0, 5)                                                     
y <- rnorm(1e4, 0, 10)  
z <- rnorm(1e4, 20, 1)

data.frame(x, y, z) %>%                                                   
  ggplot(mapping = aes(x = x, y = y, z = z)) +
  geom_hex(bins = 20)

Answer 1

You can use the following code:

library(ggplot2)
library(hexbin)
library(ggraph)

x <- rnorm(1e4, 0, 5)                                                     
y <- rnorm(1e4, 0, 10)  
z <- rnorm(1e4, 20, 1)

data.frame(x, y, z) %>%                                                                                            
  ggplot(aes(x, y, z=z)) + 
  stat_summary_hex(fun = function(x) mean(x), bins = 20) +
  scale_fill_viridis_c(option = "magma")

ggplotly()

Output: