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*Subject*: Re: Re: Clsuter analysis wiht IDL*From*: dw(at)isva.dtu.dk (Dorthe Wildenschild)*Date*: 1 Mar 2001 12:20:59 +0100*Mail-From*: dw@isva.dtu.dk from mail.isva.dtu.dk [192.38.88.3]*Newsgroups*: comp.lang.idl-pvwave*Organization*: Mailgate.ORG Server - http://www.Mailgate.ORG*Xref*: news.doit.wisc.edu comp.lang.idl-pvwave:23782

<Craig writes:

<I am by no means a statistics or clusters analysis expert, but from

<looking at the documentation it seems that both CLUST_WTS and CLUSTER

<require the n-dimensional *positions* of the data points, and not an

<intensity map. It is pretty clear that the cluster functions are

<based on an unweighted set of scatter-points. If you want to use your

<intensity information as a weighting, you may be out of luck.

<Perhaps you could achieve what you desire with this code, which simply

<finds the non-zero pixels:

wh = where(image GT 0, ct)

if ct EQ 0 then message, 'ERROR: the image is blank!'

x = wh MOD 658 ; form x pixel positions

y = floor(wh / 658) ; form y pixel positions

xy = transpose([[x],[y]]) ; compute the 2-d scatter positions

weights = clust_wts(xy, n_clusters=3)

etc.

<I haven't tried this, so it may take some tweaking. Good luck,

<Craig

I'm such a beginner at this I don't know what the MOD function does? (no on-line help listing for it)

When trying to transpose, IDL corrects me with

Arrays are allowed 1 - 8 dimensions

thanks for trying to help!

BTW I'm not a Mr. :-)

D

**Follow-Ups**:**Re: Clsuter analysis wiht IDL***From:*Craig Markwardt

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