[R] attributes of a data.frame

[Prof Brian Ripley]

On Wed, 23 Nov 2005, Peter Dalgaard wrote:

> Prof Brian Ripley <ripley at stats.ox.ac.uk> writes:
>
>> Why do you have names like 'pctx723' in the first place?
>>
>> I have never had a difficulty with using informative column names whereas
>> you seem to require the extra complication of `variable labels'.
>> Now we have `` and allow _ in syntactic names it is even easier than it
>> was.
>
> But do we want to have `Maternal height (inches)` as a variable name?
> Imagine a multiple regression with a few dozen such terms as
> predictors.

I have actually done something very like this today (it was (m), (km) 
and (ha), but you get the idea).  If you are going to have them in the 
printout of the results you may as well have them in the formula.

> We do have the comment attribute (as in help(comment)), but we're not
> using it much. There could be some reason in using a such a comment,
> if present, and possibly optionally, to name dimnames in tables and
> for x/y labels in plots. I'm not sure it is easy to do without
> disrupting existing code, though. I notice in particular that the
> comment attribute is retained according to rules that might not be
> what users expect.
>
>
>> On Tue, 22 Nov 2005, Michael Friendly wrote:
>>
>>> It's hard for me to resist dipping my oar into this...
>>>
>>> Variable labels are so generally useful, both in documenting a
>>> dataset (what was 'pctx723' again?) and in producing readable
>>> output and graphs that it is a shame they are not provided in
>>> base R.  If they were (and were used in print and plot methods,
>>> when available) it would avoid a lot of the necessity to specify
>>> xlab= and ylab= in graphs, or, perhaps worse, ending up with
>>> pctx723 as the label in your presentation.
>>>
>>> -Michael
>>>
>>>> On 11/21/2005 2:51 PM, Adrian DUSA wrote:
>>>>
>>>>>> On Monday 21 November 2005 22:41, Duncan Murdoch wrote:
>>>>>
>>>>>>>> [...snip...]
>>>>>>>> Not all dataframes have the variable.labels attribute.  I'm guessing
>>>>>>>> you've installed some contributed package to add them, or are importing
>>>>>>>> an SPSS datafile using read.spss.  So don't expect varlab() or
>>>>>>>> variable.labels() function to be a standard R function.
>>>>>
>>>>>>
>>>>>> Aa-haa... of course you are right: I read them via read.spss. I understand.
>>>>>> Now, just to the sake of it, would it be wrong to make it standard?
>>>>>> Is there a special reason not to?
>>>>
>>>>
>>>> I think it's just that the R core developers don't see the need for
>>>> them.  If something is worth documenting, then you should write an .Rd
>>>> file or a vignette about it, and that gives you more flexibility than a
>>>> one line label.
>>>>
>>>> I think there are definitely developers out there who disagree with this
>>>> point of view, and I'm pretty sure I've seen a contributed package that
>>>> offered support for this, but I can't remember which one right now.  So
>>>> that's another reason why it's not in the base:  it doesn't need to be,
>>>> you can just go find and install that contributed package!
>>
>>
>> --
>> 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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>
> -- 
>   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
>  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
> (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907
>
>

-- 
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