[R-sig-teaching] pros/cons of teaching attach()

[Murray Jorgensen]

This may not always be useful when we venture too far from the cosy 
world of lm().

For example I have just been looking at the function flexmixedruns()
from package fpc, and the object  fr  that is its value in the examples 
for that function.

 > methods(class=class(fr))

just produces the standard list methods because fr is defined as a list. 
To get stuff out you need $.

Still I like Gabor's suggestion and I will use it when a function 
returns an object of an unusual class.

Murray


On 25/09/2010 11:07 a.m., Gabor Grothendieck wrote:
>
>
> On Fri, Sep 24, 2010 at 6:25 PM, Murray Jorgensen <maj at waikato.ac.nz
> <mailto:maj at waikato.ac.nz>> wrote:
>
>     When will I ever learn to proof-read my emails?!
>     =============
>     I think what Greg sayS here is the "official wisdom" and it leads to
>     more future-proofED code as the structure of various objects can
>     change in new versions of R.
>
>
>     OTOH the structure of a kind of object can always be explored with
>     str(), but it may not be easy to find out what extractor functions
>     are available for the object.
>
> Try this using builtin data.frame, BOD, to find methods can be applied
> to fm:
>
> fm <- lm(demand ~ Time, BOD)
> methods(class = class(fm))
>
> --
> Statistics & Software Consulting
> GKX Group, GKX Associates Inc.
> tel: 1-877-GKX-GROUP
> email: ggrothendieck at gmail.com <http://gmail.com>
>


-- 
Dr Murray Jorgensen      http://www.stats.waikato.ac.nz/Staff/maj.html
Department of Statistics, University of Waikato, Hamilton, New Zealand
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