Re: [R] Dots in models formulae

From: Gavin Simpson <gavin.simpson_at_ucl.ac.uk>
Date: Wed 17 Aug 2005 - 03:49:56 EST

On Tue, 2005-08-16 at 12:24 -0500, Sundar Dorai-Raj wrote:
>
> Uwe Ligges wrote:
> > Laurent Valdes wrote:
> >
> >
> >>I have seen, several times, dots (like this: "y ~." ) in formula
> >>descriptions, noticeably in R help.
> >>
> >>I am unable to see what it does correspond to.
> >>
> >>Any ideas ?
> >
> >
> > All other variables (except y) from the given data.frame...
> >
> > Uwe Ligges
> >
>
> Hi, Uwe,
>
> Doesn't this depend on the context? For example,
>
> z <- data.frame(y = rnorm(10), x = rnorm(10))
> fit <- lm(y ~ ., z)
> update(fit, y ~ . + I(x^2))
>
> The original poster did not say where he saw this formula. However, I
> think the reference in ?formula has the most authorative explanation.

Not for "." in a formula in ?formula, at least in

platform i686-pc-linux-gnu

arch     i686
os       linux-gnu

system i686, linux-gnu
status Patched
major 2
minor 1.1
year 2005
month 08
day 15
language R

I still can't find this documented for a formula (I found update.formula, but the meaning of "." is different there, slightly, as you indicate) - but it must be as I didn't imagine seeing it - or maybe I did...

G

> Thanks,
>
> --sundar
>
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Received on Wed Aug 17 03:57:31 2005

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