Dear Paul,
Isn't this really a question for r-help rather than r-package-devel?
In any event, I think that your message is based on (an entirely
understandable) misunderstanding of what the : operator on the right-hand side
of a model formula does. The : operator is equivalent to %in%, and used
Hi all,
recently I stumbled upen a problem in stats::model.matrix that I think is
worth reporting.
When I run:
> dat <- data.frame(
> y = rnorm(8),
> x1 = factor(rep(0:1, each = 4)),
> x2 = factor(rep(rep(0:1, each = 2), 2)),
> x3 = factor(rep(0:1, 4))
> )
>
> stats::model.matrix(y ~ x1+
