geom_density to match geom_histogram binwitdh

Question

I would like to add a line to a distribution bar plot in ggplot2 to show the average distribution but am having trouble.

A ggplot call like this:

gg         


        

Answer 1

According to answer of Brian S. Diggs given in this e-mail you should multiply value of ..count.. in geom_density() by the value of binwidth= in geom_histogram().

set.seed(123)
df<-data.frame(x=rnorm(1000,100,15))

ggplot(df,aes(x))+
      geom_histogram(binwidth = 2.5)+
      geom_density(aes(y=2.5 * ..count..))