[Rd] formula(CO2)

Kevin Wright kw.statr at gmail.com
Tue Jul 17 17:14:47 CEST 2007

About a month ago I had a similar issue related to 'formula':

In summary:

In S-Plus, the help for formula.data.frame says:
This is a method for the function formula() for objects inheriting
from class data.frame. If object is a model frame, the formula for the
model frame is returned, otherwise a formula is deduced from the names
of object. The first name is taken to be the response, and all the
remaining names are pasted together additively.

In R, the help for formula.data.frame is aliased to the help for
formula, but does not clearly document the usage with data.frames.


On 7/16/07, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> The formula attribute of the builtin CO2 dataset seems a bit strange:
> > formula(CO2)
> Plant ~ Type + Treatment + conc + uptake
> What is one supposed to do with that?  Certainly its not suitable for
> input to lm and none of the examples in ?CO2 use the above.
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