ggvis fill attribute is not working for certain layers or variables

Question

Pretty straightforward:

1. This does not work

   iris %>%  
   ggvis(x= ~Sepal.Length, y = ~Sepal.Width, fill=~Sepal.Length) %>%
   layer_bars()
   

2. This it does

   iris %>%  
   ggvis(x= ~Sepal.Length, y = ~Sepal.Width, fill=~Sepal.Length) %>% 
   layer_points()
   

Why?

I actually managed to use the fill aesthetic with another dataset that I am not sharing, but that's just to point out that the fill should definitely work in my replicable example, right?

Answer 1

From ?layer_bars

If grouping var is continuous, you need to manually specify grouping

iris %>%  
  group_by(Sepal.Length) %>%
  ggvis(x= ~Sepal.Length, y = ~Sepal.Width, fill = ~Sepal.Length) %>%
  layer_bars()

Which gives: