[R] cluster.stats

[Christian Hennig]

The given information is not enough to tell you what's going on. as.dist 
doesn't appear in the given code and it's not clear to me what kind of 
object img is ("a small image" doesn't tell me what R makes of it).
Also, try to read the help pages first and find out whether img is of the 
format that is required by the functions. And check (using str for example) 
whether "data" is what you expect it to be.

Christian

On Sat, 14 Jun 2008, Laura Poggio wrote:

> Thank you very much for your answer.
> I tried to run the function on my data and now I am getting this message of
> error
> Error in as.dist(dmat[clustering == i, clustering == i]) :  (subscript)
> logical subscript too long
>
> Below the code I am using (version2.7.0 of R with all packages updated):
>
> data <- <- as(img, "data.frame")[1:1]    #(where img is a small image 256 px
> x 256 px)
> kl <- kmeans(data, 5)
> library(fpc)
> cluster.stats(data, kl$cluster)
>
> Thank you for any hints on the reasons and meaning of the error!
>
> Laura
>
>
>
>
>
> 2008/6/13 Christian Hennig <chrish at stats.ucl.ac.uk>:
>
>> Dear Laura,
>>
>>  Dear list,
>>> I just tried to use the function cluster.stat in the package fpc.
>>> I just have a couple of questions about the syntax:
>>>
>>> cluster.stats(d,clustering,alt.clustering=NULL,
>>> silhouette=TRUE,G2=FALSE,G3=FALSE)
>>>
>>> 1) the distance object (d) is an object obtained by the function dist() on
>>> my own original matrix?
>>>
>>
>> d is allowed to be an object of class dist or a dissimilarity matrix.
>> The answer to your question depends on what your "original matrix" is. If
>> it is something on which you can compute a distance by dist(), you're right,
>> at least if dist() delivers the distance you are interested in.
>>
>>  2) clustering is the clusters vector as result of one of the many
>>> clustering
>>> methods?
>>>
>>
>> The help page tells you what clustering can be. So it could be the
>> clustering/partition vector of a clustering method or it could be something
>> else. Note that cluster.stats doesn't depend on any particular clustering
>> method. It computes the statistics regardless of where the clustering vector
>> comes from.
>>
>> Best regards,
>> Christian
>>
>>
>>> Thank you very much in advance and sorry for such basic question, but I
>>> did
>>> not manage to clarify my mind.
>>>
>>> Laura
>>>
>>>        [[alternative HTML version deleted]]
>>>
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>>>
>>>
>> *** --- ***
>> Christian Hennig
>> University College London, Department of Statistical Science
>> Gower St., London WC1E 6BT, phone +44 207 679 1698
>> chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche<http://www.homepages.ucl.ac.uk/%7Eucakche>
>>
>

*** --- ***
Christian Hennig
University College London, Department of Statistical Science
Gower St., London WC1E 6BT, phone +44 207 679 1698
chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche