[R] cluster with mahalanobis distance

[Phil Spector]

Albyn -
    That's a very important fact that I overlooked in my 
original response.  Thanks for pointing it out.
                                                  - Phil


On Wed, 3 Mar 2010, Albyn Jones wrote:

> Note: this procedure assumes that all clusters have the same covariance matrix.
>
> albyn
>
> On Wed, Mar 03, 2010 at 01:23:37PM -0800, Phil Spector wrote:
>> The manhattan distance and the Mahalanobis distances are quite different.
>> One of the main differences is that a covariance matrix is necessary to
>> calculate the Mahalanobis
>> distance, so it's not easily accomodated by dist.  There is a function in
>> base R which does calculate the Mahalanobis
>> distance -- mahalanobis().  So if you pass a distance matrix
>> calculated by mahalanobis() to the clustering function, you'll
>> get what you want.
>> 					- Phil Spector
>> 					 Statistical Computing Facility
>> 					 Department of Statistics
>> 					 UC Berkeley
>> 					 spector at stat.berkeley.edu
>>
>>
>> On Wed, 3 Mar 2010, Tal Galili wrote:
>>
>>> when you create the distance function to put into the hclust, use:
>>>
>>> dist(x, method = "manhattan")
>>>
>>>
>>> Tal
>>>
>>>
>>>
>>> ----------------Contact
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>>>
>>>
>>>
>>> On Wed, Mar 3, 2010 at 9:14 PM, naama <nwolf at technion.ac.il> wrote:
>>>
>>>>
>>>> How can I perform cluster analysis using the mahalanobis distance instead
>>>> of
>>>> the euclidean distance?
>>>> thank you
>>>> Naama Wolf
>>>>
>>>> --
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>>>>
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>>
>> ______________________________________________
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>>
>