Color palette don't respect the un-dropped factor level

[Yunuuuu]

Note: b has no color palette

library(ggplot2)
ggplot(data.frame(x = 1, y = 1, color = factor("a", c("a", "b")))) +
    geom_point(aes(x, y, color = color)) +
    scale_colour_brewer(palette = "Dark2", drop = FALSE)

[teunbrand]

That is right, it respects the absence of the level in the data.

[Yunuuuu]

This makes it difficult to collect guide legends using patchwork.

[teunbrand]

You can use geom_point(aes(x, y, color = color), show.legend = TRUE) to force the missing level to appear.

[Yunuuuu]

Thanks! That works well.