[R] cluster-analysis and NA's

[chr.schulz@email.de]

Hi,
thanks for the different replies.
Varclus in the Hmisc-Package is really nice and 
is exactly what i need for my intention 
(... and works with correlations what you describe below ,too) 

;-))


regards,Christian



Christian Hennig <hennig at stat.math.ethz.ch> schrieb am 08.08.02 10:38:00:
> Hi,
> 
> On Wed, 7 Aug 2002 chr.schulz at email.de wrote:
> 
> > Hi,
> > 
> > exist a special cluster-analysis algorithms
> > which can work with NA's.
> > 
> > a further "problem" is that i want cluster
> > variables not cases to identify special variable-set's.
> > 
> > Is it a common way turn the data.frame and use
> > kmeans,because this works with NA's, or have anybody another
> > method for finding "variable-sets"  , with exception of factor analysis.
> > 
> > thanks for advance
> > Christian
> 
> The choice of a clustering method depends very much on the aims of your
> analysis and especially on your concept of "similarity" between the
> entities to cluster. One of the most often used methods for clustering
> variables is to compute a dissimilarity matrix between the variables, where
> dissimilarity is defined as 1-correlation or 1-|correlation| (depending on
> if you want variables pointing in almost exactly the opposite direction 
> to be interpreted as similar or as extremely dissimilar).
> Then you can apply one of the algorithms of hclust or agnes of library
> cluster (the latter is not a bad choice as a default). 
> NAs are not a big problem because correlations can be properly computed in
> presence of NAs.
> 
> Christian
> 
> > 
> >  
> > 
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> 
> -- 
> ***********************************************************************
> Christian Hennig
> Seminar fuer Statistik, ETH-Zentrum (LEO), CH-8092 Zuerich (current)
> and Fachbereich Mathematik-SPST/ZMS, Universitaet Hamburg
> hennig at stat.math.ethz.ch, http://stat.ethz.ch/~hennig/
> hennig at math.uni-hamburg.de, http://www.math.uni-hamburg.de/home/hennig/
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> 



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