[R] update.default evaluating in wrong environment?

[Martin C. Martin]

Gabor Grothendieck wrote:
> 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)

Thanks, or even just:

e <- environment(formula(f.lm))

But this was more of a bug report.  Is update.default wrong?  Should it 
be changed?  I don't see how evaluating in update's parent environment 
would ever be better default behavior than the formula's environment.

- Martin
> 
> 
> 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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