[R] overlay boxplot

[Hao Liu]

hi, All:

I need to overlay two boxplot, I played around with points() but found 
it does not seem to work with boxplot, it works fine with other. Is 
there a way to overlay two boxplot (using different color) in R?

There was a thread talking about using ggplot package, however, I don't 
think there is a final solution... the answer give does not give overlay 
but a new plot.

Thanks
Hao