geom_bar does not play well with scale_fill_binned

[jtlandis]

As the title says, it seems that geom_bar does not interact with scale_fill_binned. I'm assuming this is because the fill aesthetic is ignored if a continuous variable is passed.

I'm not sure if there are any other geoms that would have a similar issue.

#Fill is ignored
ggplot(mpg) + 
   geom_bar(aes(displ, fill = cty)) + 
   scale_x_binned() +
   scale_fill_binned()

#likely result expected
 ggplot(mpg) + 
    geom_bar(aes(displ, fill = cut(cty, seq(8,38,6)))) + 
    scale_x_binned() 

[thomasp85]

The reason you are seeing this is that a grouping cannot be made based on a continuous fill. since grouping is resolved before scale transformations are done this 'discreteness' of the bins does not come into effect.

I'm not sure if this is possible to fix unfortunately...

[thomasp85]

One particular way this could be fixed would be to consult the scales before deriving a default group. Right now the logic only looks at whether the mapped variable is "discrete-like" but maybe this could go through the scale for each aesthetic...

However, at this point the scales have not been trained yet so it is probably not possible for the binned scale to assign the expected grouping...

This is probably a wont-fix, but I'll kick it over to the next feature release to let me think about it some more

[teunbrand]

I'm bumping in the same limitation that Thomas mentions here. Under typical circumstances, this should be fixed by manually setting the group aesthetic, but at this point the benefit of the binned scales becomes moot. As such, I'll close this issue as a 'wont-fix'.