Following up on your comments it seems formula.data.frame just creates a formula whose lhs is the first column name and whose rhs is made up of the remaining column names. It ignores the "formula" attribute.
In fact, CO2 does have a formula attribute but its not extracted by formula.data.frame: > [EMAIL PROTECTED] uptake ~ conc | Plant > formula(CO2) Plant ~ Type + Treatment + conc + uptake Is this really how its supposed to work??? On 7/16/07, Ted Harding <[EMAIL PROTECTED]> wrote: > On 16-Jul-07 13:28:50, Gabor Grothendieck 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. > > I think one is supposed to ignore it! (Or maybe be inspired to > write a mail to the list ... ). > > I couldn't find anything that looked like the above formula from > str(CO2). But I did spot that the order of terms in the formula: > Plant, Type, treatment, conc, uptake, is the same as the order > of the "columns" in the dataframe. > > So I tried: > > D<-data.frame(x=(1:10),y=(1:10)) > > formula(D) > x ~ y > > So, lo and behold, D has a formula! > > Or does it? Maybe if you give formula() a dataframe, it simply > constructs one from the "columns". > > Best wishes, > Ted. > > -------------------------------------------------------------------- > E-Mail: (Ted Harding) <[EMAIL PROTECTED]> > Fax-to-email: +44 (0)870 094 0861 > Date: 16-Jul-07 Time: 14:57:28 > ------------------------------ XFMail ------------------------------ > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
