Re: Clsuter analysis wiht IDL

[Gonzalo Rojas <grojasy(at)puc.cl>]

Hi Dorthe:

   what is the difference between the obsolete IDL procedure "kmeans" and the
new "cluster" ?... In theory, with this procedures we get the same results, but
I tested it with the same input parameters (same image, quantity of clusters,
etc, etc), and we got different results...

   could you please send me the answers to my e-mail to, because I don't read
this newsgroup very often...

   thanks in advance...

Gonzalo Rojas


Dorthe Wildenschild wrote:

> 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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