Joris, Basically, the I() function, as it is used in a regression model, allows the user to perform arithmetic operations on a variable that would otherwise be interpreted by the formula. It is not trapped as a special function as Error() is in aov(). There may be other applications where the class "AsIs" is needed, so there are support functions for subscripting, formatting, printing and so forth. Dave
On Fri, Oct 3, 2014 at 7:32 AM, Joris Meys <jorism...@gmail.com> wrote: > Dear all, > > I'm updating a package regarding a new type of models, and I'm looking to > extend the formula interface with two functions (L() and R() ) for > construction of these models. I want to use as much of the formula > interface as possible, and hoped to do something similarly to I(). > > I know the I() function does nothing more than add the class "AsIs". I've > been browsing the source code of R for a couple of days now trying to > locate where this class assignment gets translated into a specific action, > but i couldn't locate it. I've been as far as the internal C function > modelframe. > > Any pointers on how I() is processed internally are greatly appreciated. > > Cheers > Joris > > -- > Joris Meys > Statistical consultant > > Ghent University > Faculty of Bioscience Engineering > Department of Mathematical Modelling, Statistics and Bio-Informatics > > tel : +32 9 264 59 87 > joris.m...@ugent.be > ------------------------------- > Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php > > [[alternative HTML version deleted]] > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
