[R] test for a formulae
thomas at biostat.washington.edu
Fri Jun 2 18:11:38 CEST 2000
On Fri, 2 Jun 2000, Prof Brian D Ripley wrote:
> On Fri, 2 Jun 2000, Paulo J. Ribeiro Jr wrote:
> > I'd like to check within a whether an argument is a formulae of the type
> > ~X or similar.
> > What's the right way to do so?
> > I'm using: is.language(obj) but not sure this is right
> That allows lots of other things.
> Formulae have class "formula", so inherits(obj, "formula") looks best.
And if you want to ensure that it is ~X+Z+W rather than Y~X+Z+W you can
inherits(obj,"formula") && (length(obj)==2)
Assistant Professor, Biostatistics
University of Washington, Seattle
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