[R] Date on x-axis of xyplot

David James dj at research.bell-labs.com
Wed Sep 17 15:51:37 CEST 2003

Prof Brian Ripley wrote:
> On Tue, 16 Sep 2003, Deepayan Sarkar wrote:
> > Is the date class standard enough to warrant including a check for it in 
> > lattice ?
> I don't think so.  The POSIX*t classes in R are the most standard, 
> followed by the chron package and only then the date package.

If it is not overly complicated to implement, could I timidly suggest
*not* checking for specific classes inside lattice, but rather use
some other kind of mechanism (perhaps invoking helper functions,
or use specific methods, etc.) to render axes?

A common rule-of-thumb among object-oriented programmers (Mark
Lutz in "Programming Python" comes to mind) is to avoid code that
switches explicitly among classes/types of objects -- such code tends
to be hard to extend when new classes of objects are introduced 
(and extremely hard in R, if package bindings are ever locked,
as namespaces may allow already or in the future).

> -- 
> 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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David A. James
Statistics Research, Room 2C-253            Phone:  (908) 582-3082       
Bell Labs, Lucent Technologies              Fax:    (908) 582-3340
Murray Hill, NJ 09794-0636

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