Remove some legend entries in ggplot

Question

I would like to remove some legend entries in my ggplot.

Previously, this was possible by defining the breaks parameter in the relevant scale, as explained here. However, that functionality seems to be broken with a recent update.

Example:

ggplot(mtcars) + 
  
  geom_col(aes(x = 1:nrow(mtcars), y = disp, fill = paste(cyl))) +
  
  scale_fill_manual(values = c("grey50", "grey60", "grey70"),
                    breaks = c("4"))

While this code snippet only diplays one legend item, as intended, it does not allow to control the colours of the non-displayed elements.

With the breaks attribute omitted:

Answer 1

Use a named values argument:

ggplot(mtcars) + 
  geom_col(aes(x = 1:nrow(mtcars), y = disp, fill = paste(cyl))) +
  scale_fill_manual(values = c("4" = "red", "6" = "green", "8" = "blue"),
                    breaks = c("4"))