Given the following example I would like to rearrange the densities by size, so that the biggest area (the group of "ideal") is in the back and the smallest area (the group of "fair") is in the front. This would facilitate the interpretation especially if the areas vary considerably in size.
ggplot(diamonds, aes(depth, fill = cut, colour = cut, weight=price)) +
geom_density(alpha = 0.5) +
xlim(55, 70)
