Clsuter analysis wiht IDL

[dw(at)isva.dtu.dk (Dorthe Wildenschild)]

I am trying to use the cluster analysis utility in IDL, and I can't work it 
out. Perhaps due to my lack of knowledge in the statistical field.....

I have a 2D-image (658x658) with a single band of info (CT x-ray 
intentities) that I want to classify (into three classes) using cluster 
analysis. I assume I have to use the CLUST_WTS function first and then the 
CLUSTER function, but I can't work it out.
The on-line help isn't very helpful on this topic....

If I use
weights = clust_wts(image, n_clusters=3), with image= intarr(658x658) I get 
alot of floating errors.
Do I need to reform the image to (658x658,1) before using the clust_wts 
function? Doesn't seem to work either, though. Also how do I get the 
cluster numbers back as an overlay of my image? so that I can actually see 
the result of the classification.

Has anybody worked on cluster analysis using IDL?

Thanks for any help!
Dorthe


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