From Kurt.Hornik@ci.tuwien.ac.at  Mon Jul 28 14:23:48 1997
From: Kurt.Hornik@ci.tuwien.ac.at (Kurt Hornik)
Date: Mon, 28 Jul 1997 15:23:48 +0200
Subject: R-alpha: R 0.50.a1 problems with lm/glm methods
Message-ID: <199707281323.PAA18639@aragorn.ci.tuwien.ac.at>

Thanks for fixing formula() and update().

Here are some open problems.

* effects:

** There is no help available for effects()

** The lm() help page has effects(lm.obj), but from the code it is clear
that the one-arg version cannot work.

Shouldn't it simply return z$effects?

** The two-arg version only works for factors (?) ... otherwise,
	z$model.frame[factors & pattern != 0]
gives an error.  Can someone explain to me what this is doing?

* plot:

There should be a plot.lm() function which reports that useful
diagnostic plots have not been implemented yet.

Perhaps we should do something like

	unimplemented <- function () {
		stop("Not implemented yet ... sorry.")
	}

	plot.lm <- function (...) unimplemented()
	plot.glm <- function (...) unimplemented()

and similarly for other stuff which is known to be missing?  (This would
also help improving the TASK handling :-))

* predict:

** There is no help available for predict()

** The one-arg version of predict.default() cannot work.  For objects
of class "lm", it should simply return the fitted values, right?

** The two-arg version of predict.default() cannot work because no
fitted object has a "covmat" component.  Anyway, shouldn't the general
form be something like
	predict(object, newdata, ...)
???

Thanks,
-k
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R-alpha: R 0.50.a1 problems with lm/glm methods
Kurt Hornik