“Density” curve overlay on histogram where vertical axis is frequency (aka count) or relative frequency?

Question

Is there a method to overlay something analogous to a density curve when the vertical axis is frequency or relative frequency? (Not an actual density function, since the ar

Answer 1

library(ggplot2)
smoothedHistogram <- function(dat, y, bins=30, xlabel = y, ...){
  gg <- ggplot(dat, aes_string(y)) + 
    geom_histogram(bins=bins, center = 0.5, stat="bin", 
                   fill = I("midnightblue"), color = "#E07102", alpha=0.8) 
  gg_build <- ggplot_build(gg)
  area <- sum(with(gg_build[["data"]][[1]], y*(xmax - xmin)))
  gg <- gg + 
    stat_density(aes(y=..density..*area), 
                 color="#BCBD22", size=2, geom="line", ...)
  gg$layers <- gg$layers[2:1]
  gg + xlab(xlabel) +  
    theme_bw() + theme(axis.title = element_text(size = 16),
                       axis.text = element_text(size = 12))
}

---

dat <- data.frame(x = rnorm(10000))
smoothedHistogram(dat, "x")