Could the NA default colour be set for a discrete scale where it is wanted to set colours for multiple levels?

[davidhodge931]

Hi,

It'd be great if ggplot2 had functionality to set the default NA colour for a discrete colour/fill scale where one wants to use different colours for different numbers of levels.

So for example, in the below code, I'd like to be able to also set the default NA colour to "red".

library(tidyverse)
library(palmerpenguins)

options(
    ggplot2.discrete.colour =
      list(
        c('red', "blue"),
        c("green", "yellow", "navy")
      )
  )

penguins |> 
  ggplot() +
  geom_point(aes(x = flipper_length_mm, 
                 y = body_mass_g, 
                 colour = sex))
#> Warning: Removed 2 rows containing missing values or values outside the scale range
#> (`geom_point()`).

penguins |> 
  mutate(species = as.character(species)) |> 
  mutate(species = ifelse(flipper_length_mm > 220, NA, species)) |> 
  ggplot() +
  geom_point(aes(x = flipper_length_mm, 
                 y = body_mass_g, 
                 colour = species))
#> Warning: Removed 2 rows containing missing values or values outside the scale range
#> (`geom_point()`).

^{Created on 2024-04-19 with reprex v2.1.0}

[teunbrand]

The infrastructure to pass na.value via the palette isn't present, so this would be pretty invasive to solve. I'm not saying it can't be done, but it wouldn't be easy.

[davidhodge931]

Ah okay, feel free to close if you think @teunbrand