[R] plot hclust - canberra dist + median linkage

Dan Bolser dmb at mrc-dunn.cam.ac.uk
Tue Oct 12 21:04:04 CEST 2004

On Tue, 12 Oct 2004, Martin Maechler wrote:

>>>>>> "Dan" == Dan Bolser <dmb at mrc-dunn.cam.ac.uk>
>>>>>>     on Mon, 11 Oct 2004 16:21:53 +0100 (BST) writes:
>    Dan> Gives strange results.
>    Dan> I get 'weird' dendrograms with canberra / binary distance metric and
>    Dan> median / centroid cluster methods.
>it doesn't depend on the metric: 
>Both 'median' and 'centroid' methods are known to *not*
>guarantee ``monotone distance measures'', or equivalently to
>possibly lead to dendrograms with so called ``inversions''.
>We should add this to help page for hclust().

Cool, I could do with more to read about these methods. It might be worth
noteing that no bootstrap exists for the method (implemented in R that

How can I quickly run a test on a sub-set of x? (i.e. quick bootstrap by


>Probably for this reason, agnes() from the cluster package
>doesn't have these two methods [explicitly] -- though it now
>allows general parameter Lance-William formula methods which can
>also lead to inversions.
>    Dan> Is this just my data?
>evidently not.  Though the problem does not appear for all data
>Martin Maechler

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