Thanks a lot, Marc!
Dimitri

On Mon, Mar 11, 2013 at 4:28 PM, Marc Schwartz <marc_schwartz@me.com> wrote:

>
> On Mar 11, 2013, at 1:46 PM, Dimitri Liakhovitski <
> dimitri.liakhovitski@gmail.com> wrote:
>
> > Hello, and apologies for not providing an example. However, my question
> is
> > more general.
> >
> > I have a lengthy function. This function is using another internal
> function
> > that modifies the data frame I am reading in. This internal function is
> > using the command model.frame (with data and weights inside) and returns
> a
> > data frame I am using for further analyses.
> > However, when I try to run my function (which has an lm or a glm
>  commmand)
> > using that new data frame and separately defined weights, I get an error:
> > can't find your weights object.
> > This happens despite the fact that I actually print the weights object
> > right before the glm command. The object is there - I can see it using
> > ls(). I checked and rechecked - there are no typos.
> > Interestingly, this happens only when I run it as a function.
> >
> > When I rename my arguments, go inside the function and run it line by
> line
> > - I don't get this problem. Clearly, something is happening with my
> weights
> > in the function environment. I was thinking - can it be that once I've
> used
> > model.frame - everything else - like glm and lm - is confused as to what
> > the weights are and doesn't want to take the weights I hand over to it
> but
> > is looking for them elsewhere?
> >
> > Thank you!
> > Dimitri
>
>
> Many discussions on this over the years, along with the 'subset' argument.
> From the Details section of ?lm:
>
>   All of weights, subset and offset are evaluated in the same way as
> variables in formula,
>   that is first in data and then in the environment of formula.
>
> You might also review:
>
>   http://developer.r-project.org/nonstandard-eval.pdf
>
> This post by Thomas from 2006 may be helpful:
>
>   http://tolstoy.newcastle.edu.au/R/devel/06/06/5869.html
>
> and the reply from Peter also:
>
>   http://tolstoy.newcastle.edu.au/R/devel/06/06/5868.html
>
> Regards,
>
> Marc Schwartz
>
>


-- 
Dimitri Liakhovitski

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