[R] Clustering with ordinal data

[Michael Bedward]

Hello Steve,

> I've been asked to help evaluate a vegetation data set, specifically to
> examine it for community similarity. The initial problem I see is that the
> data is ordinal.   At best this only captures a relative ranking of
> abundance and ordinal ranks are assigned after data collection.

Just about every vegetation survey ever conducted uses either presence
absence or ordinal data collection (e.g. Braun-Blanquet scores or
importance scores from nested quadrats).

A large number of distance metrics are in the literature to deal with
such data. As well as Phil's suggestion you should definitely look at
the vegan package which contains a good selection of these metrics
plus numerous functions frequently used in classification and
ordination of veg data.

Michael


On 20 October 2010 05:14,  <Steve_Friedman at nps.gov> wrote:
>
> Hello
>
> I've been asked to help evaluate a vegetation data set, specifically to
> examine it for community similarity. The initial problem I see is that the
> data is ordinal.   At best this only captures a relative ranking of
> abundance and ordinal ranks are assigned after data collection.    I've
> been trying to find a procedure in R that can handle ordinal based
> classification and so far have not found one.
>
> Does one exist ?  If there is one, which package supports this type of
> analysis and  what is the function ?
>
> Thanks in advance.
> Steve
>
>
>
>
> Steve Friedman Ph. D.
> Spatial Statistical Analyst
> Everglades and Dry Tortugas National Park
> 950 N Krome Ave (3rd Floor)
> Homestead, Florida 33034
>
> Steve_Friedman at nps.gov
> Office (305) 224 - 4282
> Fax     (305) 224 - 4147
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>