Re: DM: Clustering and categorical attributes (fwd)

[Murray Jorgensen]

Surely someone, somewhere has mapped US zip codes onto a two or three
dimensional grid. (Maybe even someone in SAS Institute!) Then you 
could
replace the zips with two or three numeric grid coordinates.

Murray
At 19:09 12/01/98 -0500, Warren Sarle wrote:
>I wrote:
>> There is nothing inherently wrong with doing k-means on dummy 0|1
>> variables generated from categorical attributes.
>
>Murray Jorgensen <maj@waikato.ac.nz> replied:
>> True, but when dealing with attributes with 1000 levels you would 
>need to
>> generate 999 dummy variables for each of these. I see things 
>starting to
>> get a little messy!
>
>What's really messy is when people want to use zip codes with 20,000
>levels, many of which have only one or two cases. In such situations,
>I ask "Do you really want to do that?" and they say "Yes!" <sigh>
>
>But assuming there are adequate data to support the analysis,
>generating a few thousand dummy variables isn't all that bad.
>It's certainly less hassle than computing a distance matrix when
>you have a million cases!
>
>-- 
>
>Warren S. Sarle       SAS Institute Inc.   The opinions expressed 
>here
>saswss@unx.sas.com    SAS Campus Drive     are mine and not 
>necessarily
>(919) 677-8000        Cary, NC 27513, USA  those of SAS Institute.
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>
>