[R] passing known medoids to clara() in the cluster package
dylan.beaudette at gmail.com
Mon Apr 10 23:25:27 CEST 2006
Thanks for the reply.
On Sunday 09 April 2006 11:46 pm, Martin Maechler wrote:
> >>>>> "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().
Ah. that would explain things ! :) . I will check back periodically to see
when this feature is completed.
> Unfortunately it's not true that clara() was a wrapper to pam()
> as you state above.
I must have misread the manual pages...
> 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?
I will give pam() a try, and see if it can handle the large dataset that I am
currently using clara() for -- usually only about 5 seconds are required for
clara() to complete.
Soils and Biogeochemistry Graduate Group
University of California at Davis
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