Re: [R] *not* using attach() *but* in one case ....

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Thu, 19 May 2011 10:34:27 -0400

From: Prof Brian Ripley
>
> Hmm, load() does have an 'envir' argument. So you could simply use
> that and with() (which is pretty much what attach() does internally).
>
> If people really wanted a lazy approach, with() could be extended to
> allow file names (as attach does).

I'm not sure if laziness like this should be encouraged.

If I may bring up another "black hole": IMHO the formula interface allows too much flexibility (perhaps to allow some laziness?) that beginners and even non-beginners fall into its various traps a bit too often, and sometimes not even aware of it. It would be great if there's a way to (optionally?) limit the scope of where a formula looks for variables.  

Just my $0.02...

Andy

> On Thu, 19 May 2011, Martin Maechler wrote:
>
> > [modified 'Subject' on purpose;
> > Good mail readers will still thread correctly, using the
> 'References'
> > and 'In-Reply-To' headers, however, unfortunately,
> > in my limited experience, good mail readers seem to
> disappear more and more ..
> > ]
> >
> >>>>>> Peter Ehlers <ehlers_at_ucalgary.ca>
> >>>>>> on Tue, 17 May 2011 06:08:30 -0700 writes:
> >
> > > On 2011-05-17 02:22, Timothy Bates wrote:
> > >> Dear Bryony: the suggestion was not to change the name of
> > >> the data object, but to explicitly tell glm.nb what
> > >> dataset it should look in to find the variables you
> > >> mention in the formula.
> > >>
> > >> so the salient difference is:
> > >>
> > >> m1<- glm.nb(Cells ~ Cryogel*Day, data = side)
> > >>
> > >> instead of
> > >>
> > >> attach(side) m1<- glm.nb(Cells ~ Cryogel*Day)
> > >>
> > >> This works for other functions also, but not uniformly as
> > >> yet (how I wish it did and I could say hist(x, data=side)
> > >> Instead of hist(side$x)
> > >>
> > >> this inconsistency encourages the need for attach()
> >
> > > Only if the user hasn't yet been introduced to the with()
> > > function, which is linked to on the ?attach page.
> >
> > > Note also this sentence from the ?attach page:
> > > ".... attach can lead to confusion."
> >
> > > I can't remember the last time I needed attach().
> > > Peter Ehlers
> >
> > Well, then you don't know *THE ONE* case where modern users of
> > R should use attach() ... as I have been teaching for a while,
> > but seem not have got enought students listening ;-) ...
> >
> > --- Use it instead of load() {for save()d R objects} ---
> >
> > The advantage of attach() over load() there is that loaded
> > objects (and there maye be a bunch!), are put into a separate
> > place in the search path and will not accidentally overwrite
> > objects in the global "workspace".
> >
> > Of course, there are still quite a few situations {e.g. in
> > typical BATCH use of R for simulations, or Sweaving, etc} where
> > load() is good enough, and the extras of using attach() are not
> > worth it.
> >
> > But the unconditional "do not use attach()"
> > is not quite ok,
> > at least not when you talk to non-beginners.
> >
> > Martin Maechler, ETH Zurich
>
> --
> Brian D. Ripley, ripley_at_stats.ox.ac.uk
> Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
> University of Oxford, Tel: +44 1865 272861 (self)
> 1 South Parks Road, +44 1865 272866 (PA)
> Oxford OX1 3TG, UK Fax: +44 1865 272595
>
> ______________________________________________
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> PLEASE do read the posting guide
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu 19 May 2011 - 14:41:12 GMT

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