Re: [R] Dots in models formulae

From: Sundar Dorai-Raj <sundar.dorai-raj_at_pdf.com>
Date: Wed 17 Aug 2005 - 03:24:37 EST

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.

Thanks,

--sundar



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