[R] Overlay plots from different data sets using the Lattice package

[Dieter Menne]

hadley wickham <h.wickham <at> gmail.com> writes:

> qplot(vals, ..density.., data = data.frame.A, geom="histogram", facets
> = factor.1 ~ factor.2, binwidth = 1) + geom_density(data=data.frame.B)

uhh.. how should I understand "y (?)=..density.."

Dieter