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Re: fast search [message #50818 is a reply to message #50811]

Tue, 17 October 2006 05:53

Paolo Grigis
Messages: 171
Registered: December 2003

Senior Member

This link may be useful to you:

http://www.dfanning.com/code_tips/pts_in_sphere.html

Ciao,
Paolo

m.goullant@gmail.com wrote:
> Hi there,
>
> I have the following problem:
>
> ;data structure of an irregular point cloud
> x = points.x
> y = points.y
> z = points.z
>
> search radio
> radio = 8
>
> FOR i=0L,N_ELEMENTS(z)-1 DO BEGIN
>
> square = WHERE(x LE x[i] + radio AND x GE x[i] - radio AND y LE
> y[i] + radio AND y GE y[i] - radio)
> ;(...)
>
> ENDFOR
>
> I realize that WHERE will do the job, but at very low efficiency.
> WHERE
> makes no assumptions about the list being ordered. It seems to me it
> has
> to check every element of the array, requiring N steps for an N-element
> array
>
> There is a faster way to do this?
>
> thanks,
> Marie
>

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[Message index]

		Re: fast search By: greg michael on Wed, 18 October 2006 08:25
		Re: fast search By: greg michael on Tue, 17 October 2006 11:25
		Re: fast search By: greg michael on Tue, 17 October 2006 10:17
		Re: fast search By: greg michael on Tue, 17 October 2006 07:15
		Re: fast search By: Paolo Grigis on Tue, 17 October 2006 05:53
		Re: fast search By: m.goullant@gmail.com on Thu, 19 October 2006 04:01
		Re: fast search By: m.goullant@gmail.com on Thu, 19 October 2006 03:46

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