ggplot2 aes(x=rating) geom_histogram() geom_density()

http://www.cookbook-r.com/Graphs/Plotting_distributions_(ggplot2)/

df <- data.frame(cond = factor( rep(c("A","B"), each=200)), 

+                   rating = c(rnorm(200), rnorm(200, mean=.8)))

> qplot(df$rating, binwidth=.5)

> ggplot(df, aes(x=rating)) + geom_histogram(binwidth=.5)

> ggplot(df, aes(x=rating)) + geom_histogram(binwidth=.5, colour="black", fill="white")

> ggplot(df, aes(x=rating)) + geom_density()

> ggplot(df, aes(x=rating)) + 

+     geom_histogram(aes(y=..density..),      # Histogram with density instead of count on y-axis

+                    binwidth=.5,

+                    colour="black", fill="white") +

+     geom_density(alpha=.2, fill="#FF6666")  # Overlay with transparent density plot

> ggplot(df, aes(x=rating)) + geom_histogram(binwidth=.5, colour="black", fill="white") + 

+     facet_grid(cond ~ .) +

+     geom_vline(data=cdf, aes(xintercept=rating.mean),

+                linetype="dashed", size=1, colour="red")