Suppose e.g. I want to shade the area under the density curve for the standard normal distribution by decile. I want the left-most 10% of the area to have a different shading to the next 10% and so on.
This is a variant on the questions "Shading a kernel density plot between two points" and "ggplot2 shade area under density curve by group", but I want to shade each quantile (in my example, each group is a decile but the process should easily generalise to other quantiles).
I don't mind whether a solution uses ggplot2
or base
graphics, and whether this is done directly from a formula (which would be really neat) or based on making a data frame first. If the latter, you may want:
delta <- 0.0001
z.df <- data.frame(x = seq(from=-3, to=3, by=delta))
z.df$pdf <- dnorm(z.df$x)
z.df$decile <- floor(10*pnorm(z.df$x) + 1)
Note that the naive solution ggplot(z.df, aes(x = x, fill = quantile)) + geom_ribbon(aes(ymin = 0, ymax = pdf))
would fail because Aesthetics can not vary with a ribbon
.
Best Answer
Actually aesthetics can vary with
geom_ribbon(...)
(orgeom_area(...)
, which is basically the same thing), as long as you set thegroup
aesthetic as well.Setting
quantiles <- 20
at the beginning produces this: