Add second x-axis in ggplot2

Question

In the \"graphics\" package one can add a second x-axis (indicating the percentiles of the distribution) to a histogram as follows:

x  <- rnorm(1000)
hist(x,          


        

Answer 1

I'm not entirely certain what you're after, since your first example doesn't actually produce what you describe.

But in terms of simply adding the percentage along with the raw value along the x axis, the easiest strategy would probably be to simply combine the two with a line break in a single set of labels:

dat <- data.frame(x = rnorm(1000))
perc <- quantile(dat$x,seq(from = 0,to = 1,by = 0.1))
l <- paste(round(perc,1),names(perc),sep = "\n")
> ggplot(dat,aes(x = x)) + 
     geom_histogram() + 
     scale_x_continuous(breaks = perc,labels = l)