[R] problem with model.matrix
Prof Brian Ripley
ripley at stats.ox.ac.uk
Fri Jun 25 08:06:42 CEST 2004
On Fri, 25 Jun 2004, Berwin A Turlach wrote:
> >>>>> "BN" == Balasubramanian Narasimhan <naras at stanford.edu> writes:
> BN> Trevor's problem is reproducible on R 1.8.1 (which is what he
> BN> was using) on both Linux RHEL 3.0 and Solaris and R 1.8.0 on
> BN> Windows.
> Yep, on my Linux box (details below) I have the same problem with R
> 1.8.1 but no problem under R 1.9.0 or R 1.9.1.
> Time to upgrade I would say. :)
Here is the reason (NEWS for 1.9.0)
o contrasts() turns a logical variable into a factor. This now
always has levels c("FALSE", "TRUE") even if only one (or
none) of these occur in the variable.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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