Dots in models formulae

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