Stack overlapping objects on top of one another
See layer and qplot for more information on creating a complete plot from multiple components.
> ggplot(mtcars, aes(x=factor(cyl), fill=factor(vs))) + geom_bar() > > ggplot(diamonds, aes(x=price)) + geom_bar() > ggplot(diamonds, aes(x=price, fill=cut)) + geom_bar() >