[R] lattice panel layout like cross-tabs, like a 2 x 2 table.

[Christopher W. Ryan]

Years ago, I recall creating lattice plots with two binary factors, call
them f1 and f2, as in

xyplot(y ~ x | f1 + f2, data = dd)

and I made it so the rows had strips on the left with the levels of one
factor, and the columns had strips on the top with the levels of the
other factor.  Sort of like strip.left() but for just one of the factors.

I can't remember or find how I did it, what options to set. Can anyone
remind me?

Thanks.

--Chris Ryan