ggplot(faithful, aes(eruptions, waiting)) + stat_density2d(aes(colour = ..level..))

x <- sample(c('A','B','C','D'), size = 1000, replace= TRUE, prob = c(0.2,0.3,0.3,0.2))
y <- rnorm(1000) * 1000
df = data.frame(x= x, y = y)
ggplot(data = df, aes(x = factor(x), y = ..count..))+ geom_bar(stat = 'count')