[R] passing known medoids to clara() in the cluster package

Martin Maechler maechler at stat.math.ethz.ch
Mon Apr 10 08:46:41 CEST 2006

>>>>> "DylanB" == Dylan Beaudette <dylan.beaudette at gmail.com>
>>>>>     on Sun, 9 Apr 2006 19:28:44 -0700 writes:

    DylanB> Greetings, I have had good success using the clara()
    DylanB> function to perform a simple cluster analysis on a
    DylanB> large dataset (1 million+ records with 9 variables).

    DylanB> Since the clara function is a wrapper to pam(),
    DylanB> which will accept known medoid data - I am wondering
    DylanB> if this too is possible with clara() ... The
    DylanB> documentation does not suggest that this is
    DylanB> possible.

indeed, it doesn't --  because it's not yet possible.
I (as maintainer of "cluster") had added the ``known medoid''
option to pam() a while ago last June (for  cluster version 1.10.0),
and had left a note my TODO file to do the same for clara().

Unfortunately it's not true that clara() was a wrapper to pam()
as you state above.

Given your wish and clear "use case" situation, I'm more
motivated to approach this particular 'TODO' item!

Martin Maechler, ETH Zurich

    DylanB> Essentially I am trying to implement a "supervised
    DylanB> classification" of numerous geographic data
    DylanB> layers. The "unsupervised" approach using clara()
    DylanB> works well, but I feel the output classes would be
    DylanB> more meaningful if I were able to let clara() know
    DylanB> about the classes that I have in mind.

    DylanB> Is this at all feasible, or am I trying to
    DylanB> accomplish something that is not possible?

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