[R] dendrogram ultrametrics

[Christian Hennig]

Dear Lisa,

as far as I know, there is no implementation of dendrogram ultrametrics,
but it could be easily computed from the output of hclust (package mva)
or agnes (package cluster) in the following manner:
1) Generate the desired dendrogram by hclust or agnes.
2) Generate partitions for all levels by cutree.
3) For a given pair of objects, determine the level on which they are
joined.
4) Take the height component of the output object of hclust or agnes
at this level.

Perhaps it can be done faster by intelligent use of the merge component
of the output object. (Note that I didn't try it, so all this assumes that
the help pages are correct and I understood them...)

Best,
Christian

On Mon, 23 Feb 2004 Lisa.Holman at npws.nsw.gov.au wrote:

> Dear R-help listers,
> Is anyone aware of a function that outputs dendrogram ultrametrics?
> Cheers, Lisa.
> 
> PS please reply to me personally as well as to the list because the 
> website wasn't letting me subscribe for some reason.  thanks...
> 
> Lisa Holman
> Research Officer, Vegetation Dynamics
> Policy & Science Division
> NSW Department of Environment & Conservation
> PO Box 1967, Hurstville 2220.
> ph 02 9585 6507    fax 02 9585 6606
> email lisa.holman at npws.nsw.gov.au
> 
> The NPWS is part of the new Department of Environment & Conservation
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***********************************************************************
Christian Hennig
Fachbereich Mathematik-SPST/ZMS, Universitaet Hamburg
hennig at math.uni-hamburg.de, http://www.math.uni-hamburg.de/home/hennig/
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