overlapping boxes with geom_boxplot(varwidth=TRUE)

[mcol]

When I try to produce boxplots with colours depending on a categorical variable, these appear overlapping if varwidth is set to TRUE (which is what I'd like to use).

Here's an example:

ggplot(data=iris, aes(Species, Sepal.Length)) + 
   geom_boxplot(aes(colour=Sepal.Width < 3.2), varwidth=TRUE)

This raises the following warning: "position_dodge requires non-overlapping x intervals"

However, the boxes don't overlap (and no warning is raised) if varwidth is not specified.

ggplot(data=iris, aes(Species, Sepal.Length)) + 
   geom_boxplot(aes(colour=Sepal.Width < 3.2))

[hadley]

Can you please produce a reprex using the reprex package?

[mcol]

require(ggplot2)
#> Loading required package: ggplot2
ggplot(data = iris, aes(Species, Sepal.Length)) + geom_boxplot(aes(colour = Sepal.Width < 
  3.2), varwidth = TRUE)
#> Warning: position_dodge requires non-overlapping x intervals

[karawoo]

The main problem is here — within each species the variable-width boxes have different xmin values, so pos_dodge() gets called on each box separately when it should be getting called on each pair of boxes.

I think this line will also be a problem because only the width of the first box will be used. pos_dodge() probably needs to be changed to handle multiple widths.