[R] bugs or imperfect implementation?

Prof Brian D Ripley
Fri, 08 Feb 2002 15:21:27 -0000

On Fri, 8 Feb 2002, Chong Gu wrote:

>
> I am using R to teach, and here are a couple of things that I thought
> would work didn't work.
>
> 1. I noticed the utility data(***,package=***) recently and like it
> very much, but unless I type in the whole word "package" I'll
get an
> error in 1.4.0.  For example, data(cats,package=MASS) works fine but
> data(cats,pac=MASS) doesn't.
>
> 2. drop1 doesn't seem to be as smart as before.  In the sequence
> below, drop1 didn't produce what I expected it to produce.
>
>     data(HairEyeColor); lab<-dimnames(HairEyeColor)
>     HairEye<-cbind(expand.grid(Hair=lab$Hair,Eye=lab$Eye,
>         Sex=lab$Sex),Fr=as.vector(HairEyeColor))
>     HairEye.fit<-glm(Fr~.^2,poisson,HairEye)
>     drop1(HairEye.fit)
>
> The following sequence however works.
>
>     HairEye.fit<-glm(Fr~(Hair+Eye+Sex)^2,poisson,HairEye)
>     drop1(HairEye.fit)

It's not a change in drop1, though, where the basis of this (drop.scope) is
unchanged since 1999.  I suspect a side effect of changes in the
formula/terms handling.  Do you know when it did work?


--
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595