[R] Similarity matrix

[Prof Brian Ripley]

On Wed, 11 Apr 2001, Kaspar Pflugshaupt wrote:

> On Wednesday 11 April 2001 10:23, Prof Brian Ripley wrote:
>
> > I guess we have to experiment?
>
>
> Well, I've taken the time to do it for you (S-PLus 3.4/Unix):

(Unfortunately a few minutes after I had, although Frank Harrell wanted to
know.)

> According to Legendre & Legendre, the choice of similarity coefficient
> _does_ make a difference as to which conversion should be preferred. For some
> "species" of similarity coefficients, the resulting distance would be metric
> and euclidean with one method but not with the other, for others vice versa.
> I don't know if this matters for cluster analysis, but I think that it might,
> especially when clustering with an euclidean metric.

For single- and complete-link clustering only the ordering matters as far
as the clusters are concerned.

> Cheers (hoping this was to the point :-)

Thanks, it was.

Is it worth adding this to R's hclust?


-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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