R help - Mar 2004 - How to ascertain the number of clusters automatically?

Hi, everyone,

There is many small cells which can be classified into several big cells 
from the scanned image. K-means clustering does not work well in this 
condition. I have done hierarchical clustering on cells successfully which 
uses shortest distance between classes. The number of clusters is about 3, 
4, 5, 6, 7 generally. One can ascertain the number of clusters visually.  
But because there are thousands of images to be clustered. So it is humdrum 
to me. I want to know if there are any methods that can be used to ascertain 
the number of clusters automatically, especially in this case, only several 
clusters?

Thank you very much!

Best,

Fucang

Hi,
You may be interested in a clustering algorithm called OPTICS. It is both
interactive and automatic and does not require a lot of input parameters. It
is described as creating " an augmented ordering of the data representing
its density-based clustering structure". It "automatically and
efficiently
extracts not only traditional clustering information but also the intrinsic
clustering structure".
Check out this site:
http://www.dbs.informatik.uni-muenchen.de/Forschung/KDD/Clustering/
Alex

-----Original Message-----
From: Fucang Jia [mailto:jiafucang at hotmail.com] 
Sent: March 9, 2004 11:30 AM
To: r-help at stat.math.ethz.ch
Subject: [R] How to ascertain the number of clusters automatically?


Hi, everyone,

There is many small cells which can be classified into several big cells 
from the scanned image. K-means clustering does not work well in this 
condition. I have done hierarchical clustering on cells successfully which 
uses shortest distance between classes. The number of clusters is about 3, 
4, 5, 6, 7 generally. One can ascertain the number of clusters visually.  
But because there are thousands of images to be clustered. So it is humdrum 
to me. I want to know if there are any methods that can be used to ascertain

the number of clusters automatically, especially in this case, only several 
clusters?

Thank you very much!

Best,

Fucang

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