Fill aesthetic does not show in the legend guide for stat_summary

[smouksassi]

require(ggplot2)

# using default summary function no fill in the legend 
ggplot(mtcars, aes(cyl ,mpg,col=factor(am),fill=factor(am))  )+
  geom_point()+
  stat_summary(aes(cyl,mpg), geom = "smooth")

# using median_hilow summary function no fill in the legend 
ggplot(mtcars, aes(cyl ,mpg,col=factor(am),fill=factor(am))  )+
  geom_point()+
  stat_summary(aes(cyl,mpg),fun.data = "median_hilow", geom = "smooth")

# geom smooth shows the fill in the legend which is the expected behavior
ggplot(mtcars, aes(cyl,mpg,col=factor(am),fill=factor(am))  )+
  geom_point()+
  geom_smooth()

[hadley]

Hmmmm, this is because the "smooth" key only displays the fill if the se parameter is true, and stat_summary() doesn't have an se parameter.

[smouksassi]

It used to work prior to 2.0. I see many us cases where stat_summary is used to visualize uncertainty or predictions interval around a fitted line and th fill works but down not show in legend.

[hadley]

@thomasp85 if you have time, could you please take a look at this too?

[clauswilke]

Slightly simpler reprex:

library(ggplot2)
ggplot(mtcars, aes(cyl, mpg, fill = factor(am))) +
  geom_smooth()
#> `geom_smooth()` using method = 'loess' and formula 'y ~ x'
#> There were 16 warnings (use warnings() to see them)

ggplot(mtcars, aes(cyl, mpg, fill = factor(am))) +
  geom_smooth(stat = "summary")
#> No summary function supplied, defaulting to `mean_se()

Created on 2018-05-10 by the reprex package (v0.2.0).

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