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Re: efficient comparing 1D and 3D arrays [message #60684 is a reply to message #60683]

Wed, 11 June 2008 08:09

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

Jelle <post@bio-vision.nl> writes:

> Hi All,
>
> At the moment I am trying to find pixels that fall within a certain
> value range for each pixel, as part of a recursive image exploration
> routine.
>
> Say I have the following data:
>
> imgdata = fltarr(NB, NS, NL)
> MinVals = fltarr(NB)
> MaxVals = fltarr(NB)
>
> Now I would like to efficiently find out
> where( (imgdata GT MinVals) and (imgdata LT MaxVals) )
>

There are two possibilities. One is to REFORM/REBIN your MinVals and
MaxVals arrays so they are the same dimension as imgdata, then you can
do your comparison directly.

The other possibility is to make a FOR loop. If NS*NL is large, then
the overhead of the loop should be irrelevant since you are doing many
vector comparisons at each loop step.

Good luck!
Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: efficient comparing 1D and 3D arrays By: Jelle on Wed, 11 June 2008 16:05
		Re: efficient comparing 1D and 3D arrays By: Chris[5] on Wed, 11 June 2008 14:24
		Re: efficient comparing 1D and 3D arrays By: Jelle on Wed, 11 June 2008 10:29
		Re: efficient comparing 1D and 3D arrays By: Jelle on Wed, 11 June 2008 09:48
		Re: efficient comparing 1D and 3D arrays By: Jean H. on Wed, 11 June 2008 09:37
		Re: efficient comparing 1D and 3D arrays By: Jelle on Wed, 11 June 2008 08:46
		Re: efficient comparing 1D and 3D arrays By: Craig Markwardt on Wed, 11 June 2008 08:09
		Re: efficient comparing 1D and 3D arrays By: Jean H. on Wed, 11 June 2008 13:46
		Re: efficient comparing 1D and 3D arrays By: Jean H. on Wed, 11 June 2008 16:21

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