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Re: fast search [message #50889 is a reply to message #50818]

Thu, 19 October 2006 04:01

m.goullant@gmail.com is currently offline

m.goullant@gmail.com
Messages: 10
Registered: July 2006

Junior Member

Hi Paolo,

thanks for the article, i'll read cautiously!

regards,
Marie

Paolo Grigis wrote:
> 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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