geom_density doesn't fill correctly with scale_y_log10

Question

Code:

require(ggplot2)
set.seed(0)
xvar <- rnorm(100)
ggplot(data.frame(xvar), aes(xvar)) + geom_density(fill="lightblue") + scale_y_log10()

The graph is something like this:

How can I make the graph shade on the right side of (viz. below) the density estimate?

Answer 1

The problem is that stat_density by default fills between the density and the y=0 line of the transformed data. So transformations that alter the y=0 line will fall victim to problems of this sort. I personally think this is a bug in ggplot2, although since graphical grammar experts probably argue that y-transformed densities are meaningless, the bug may not get a lot of attention.

A very kludgy workaround is to manually add an offset to ..density.., which you will have to explicitly invoke, and then change the breaks to make it look like you didn't do anything weird.

require(ggplot2)
require(scales)
set.seed(0)
xvar <- rnorm(100000)
quartz(height=4,width=6)
ggplot(data.frame(xvar), aes(x=xvar, y=log10(..density..)+4)) + 
    geom_density(fill='lightblue') +
    scale_y_continuous(breaks=c(0,1,2,3,4), 
        labels=c('0.0001', '0.001', '0.01', '0.1','1'), limits=c(0,4),
        name='density')
quartz.save('![StackOverflow_29111741_v2][1].png')

That code produces this graph: