[R] Reporting ppr fits and using them externally.

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Jun 28 08:50:16 CEST 2006

It is normal to report smooth curves via plots of smooth curves. There are 
examples for ppr in MASS4 p.241 (referenced on the help page).  This is 
done by the plot() method.

Please do consult the references in the documentation: those who very 
carefully documented these tools put them there because they do give 
additional information.

On Tue, 27 Jun 2006, Robert Chatfield wrote:

> The pursuit projection packages ppr is an excellent contribution to R. 
> It is great for one-to-three ridge fits, often somewhat intuitive, and 
> for multi-ridge fits, where it at least describes a lot of variance.
> Like many folk, I need to report the fits obtained from ppr to the 
> greater, outside, non-R world.  It is fairly obvious how to use the 
> terms alpha and beta to report on directionality and importance.
> It has proven difficult to report on the spline fits generated.  We are 
> moving into some "cryptanalysis" of the uncommented "predict"  code with 
> the "ppr" method in order to locate the information, and can report, if 
> warranted.

In what sense do you claim it to be `undocumented'?  Methods should do 
what the generic is documented to do, and that is the case here.


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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