[R] Clustering with 'agnes'

Arnav Sheth sheth at economics.rutgers.edu
Thu Feb 5 15:06:02 CET 2004

```Hey Christian,

That clarifies a lot of things. Thank you.

With regards,
Arnav

----- Original Message -----
From: "Christian Hennig" <fm3a004 at math.uni-hamburg.de>
To: "Arnav Sheth" <sheth at economics.rutgers.edu>
Cc: "Uwe Ligges" <ligges at statistik.uni-dortmund.de>;
<R-help at stat.math.ethz.ch>
Sent: Thursday, February 05, 2004 8:02 AM
Subject: Re: [R] Clustering with 'agnes'

> Hi,
>
> the underlying principle of hierarchical clustering is *not* that the
> clusters can be represented by some centroid points. Most methods are
> distance based, i.e. they can be calculated also in absence of any R^p
> representation of the points.
>
> If you want to recover centroids, you should do kmeans, normal mixture
> clustering (mclust) or pam/clara. Of course you can also take the points
> belonging to an agnes cluster and compute the mean vector (or any other
> summary statistic), but that's not what hierarchical clustering is
> meant to do (it may be reasonable with Ward's method, though).
>
> Christian
>
> On Wed, 4 Feb 2004, Arnav Sheth wrote:
>
> >
> > Hi Uwe,
> >
> > Thanks for the tip. I already have row labels. My problem is, (referring
to the
> > example below) how can I get R to tell me that upto three clusters, the
points
> > are clustered around (0,0), (1,0) and (0,1)?
> >
> > Perhaps it is not even possible, I am not sure.
> >
> > With regards,
> > Arnav
>
> ***********************************************************************
> Christian Hennig
> Fachbereich Mathematik-SPST/ZMS, Universitaet Hamburg
> hennig at math.uni-hamburg.de, http://www.math.uni-hamburg.de/home/hennig/
> #######################################################################
> ich empfehle www.boag-online.de
>
>

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