scale_fill_discrete makes fills with grey when using a named vector

[vinay-swamy]

Hi,
I'm having a problem with scale_fill_discrete, where if I provide a named vector of colors as input, the colors are filled as grey. However, If I use an unnamed vector for the same colors, the plot works fine

This does not work

library(ggplot2)
data(iris)
pal <- c('amethyst' ="#F0A0FF" , 'blue' ="#0075DC" , 'caramel'= "#993F00" )

ggplot(iris)  + 
  geom_boxplot(aes(x=Species, y=Petal.Length, fill = Species))+
  scale_fill_discrete(type = pal)+
  theme_classic()

This does work

library(ggplot2)
data(iris)
pal <- c('amethyst' ="#F0A0FF" , 'blue' ="#0075DC" , 'caramel'= "#993F00" )
names(pal) <-NULL
ggplot(iris)  + 
  geom_boxplot(aes(x=Species, y=Petal.Length, fill = Species))+
  scale_fill_discrete(type = pal)+
  theme_classic()

A bit of an edge case, but the pals package which I use a lot for my color palettes adds names to their discrete palettes.
Any idea for a solution

Session info

─ Session info ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────
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 version  R version 3.6.1 (2019-07-05)
 os       macOS Mojave 10.14.6        
 system   x86_64, darwin15.6.0        
 ui       RStudio                     
 language (EN)                        
 collate  en_US.UTF-8                 
 ctype    en_US.UTF-8                 
 tz       America/New_York            
 date     2020-09-09                  

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[karawoo]

If given a named vector, ggplot2 will match the named colors to the limits of the scale. So in your example, the following palette would work:

pal <- c("setosa" = "#F0A0FF", "versicolor" = "#0075DC", "virginica" = "#993F00")

I think this is the intended behavior and you'll have to unname or rename the palettes you want to use, or else create a custom scale as in #4087 (and using the dev version of the scales package).

[vinay-swamy]

isn't that what scale_fill_manual would before used for? personally I feel like the use case for scale_fill_discrete is to just drop in a color palette and have it auto-mapped to factor levels, and the use case for scale_fill_manual is to provide a specific color mapping.

In any case, I think it would be useful to include something like " If this is a named vector, then the values will be matched based on the names instead. Data values that don't match will be given na.value."(which is from the scale_*_manual doc) to the documentation for scale_fill_discrete

[yutannihilation]

In any case, I think it would be useful to include something like " If this is a named vector, then the values will be matched based on the names instead. Data values that don't match will be given na.value."(which is from the scale_*_manual doc) to the documentation for scale_fill_discrete

Sounds good to me. Would you mind creating a pull request for this?

[vinay-swamy]

I made a pull request (#4243)