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

[Dylan Beaudette]

Martin,

Just wanted to check on the status of including known medoids into calls to 
the clara() function within the cluster package.

Cheers,

Dylan

On Monday 10 April 2006 14:25, Dylan Beaudette wrote:
> 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?
>
> Thanks Martin!
>
> 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.

-- 
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341