Histogram of mean per bin

[Doug Mitarotonda]

Hi,

I am trying to create a histogram where the bin heights are the mean of the values that fall into each bin. The code for p2 below is what I thought would work.

library(ggplot2)

m <- mtcars[1:20, ];

p <- ggplot(m, aes(x = mpg)) + geom_histogram(binwidth = 5);

p <- p + aes(weight = wt); # works, but is the sum of the wt

p2 <- p + aes(weight = wt / ..count..); # does not work, but the idea I am going for

Sorry if I am missing something obvious here, but I appreciate the help.

Doug