Including the na.value color in the legend

[tlyons253]

I've seen a variety of options on StackOverflow but none seem to work. I set a na.value color for scale_fill_grass_c() but I cannot find a way to add that color to the legend with a label. Is there some argument I am missing or hack to this?

[dieghernan]

I think this is only valid for the discrete version via na.translate:

na.translate

Unlike continuous scales, discrete scales can easily show missing values, and do so by default. If you want to remove missing values from a discrete scale, specify na.translate = FALSE.

https://ggplot2.tidyverse.org/reference/scale_colour_discrete.html