R help - Oct 2006 - update.default evaluating in wrong environment?

Hi all,

update.default, which is the method used to update "lm" objects (among
others), extracts the "call" element from it's first argument,
updates
it, then evaluates it in the parent.frame().  Shouldn't it be evaluated
in environment(formula(object)), if that's non-NULL?

I ask because I call "lm" from within a function, and the data
argument
is a local variable of that function.  After that, I can't update the
model any more, since the new lm() call (the one evaled in
parent.frame()) can't find the data.

Best,
Martin

As a workaround use evaluate=FALSE argument to update and
evaluate it yourself fetching the environment from the innards
of the lm structure:

f <- function() {
   DF <- data.frame(y = 1:12, x1 = gl(2, 1, 12), x2 = gl(2,6))
   lm(y ~ x1, DF)
}

f.lm <- f()
e <- attr(terms(f.lm), ".Environment")
eval(update(f.lm, formula = y ~ x2, evaluate = FALSE), e)


On 10/10/06, Martin C. Martin <martin at martincmartin.com>
wrote:
> Hi all,
>
> update.default, which is the method used to update "lm" objects
(among
> others), extracts the "call" element from it's first
argument, updates
> it, then evaluates it in the parent.frame().  Shouldn't it be evaluated
> in environment(formula(object)), if that's non-NULL?
>
> I ask because I call "lm" from within a function, and the data
argument
> is a local variable of that function.  After that, I can't update the
> model any more, since the new lm() call (the one evaled in
> parent.frame()) can't find the data.
>
> Best,
> Martin
>
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