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Re: Vector comparison. [message #37049 is a reply to message #37048]

Thu, 20 November 2003 09:35

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

David Fanning <david@dfanning.com> writes:
> Timm Weitkamp writes:
>
>> Darnit! I was so proud of my answer... only to find that Chris Lee already
>> proposed the same method (the "memory-hogging" one), albeit using more
>> lines and this "if count eq 0 then ..." after WHERE, which always annoys
>> me for some stupid reason. It can be avoided, which gives me an excuse to
>> post my suggestion anyway:
>>
>> function Get_Match, a, b
>> na = n_elements(a) & nb = n_elements(b)
>> return, where(total((rebin(a,na,nb) - rebin(transpose(b), na, nb)) eq 0, 2))
>> end
>
> Now there you go! That's a solution I can
> steal for my web page. :-)

I think this is the same solution as Tom McGlynn. This is a classic
solution by brute force *memory* hogging instead of compute hogging.

If the lists are really large, then the arrays will be
n_elements(a)*n_elements(b) in size, which can be pretty big. For
example if each list had 10000 elements, then those 100 million
element arrays would start to suck a large amount of virtual memory.

Craig

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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: Vector comparison. By: JD Smith on Thu, 20 November 2003 11:38
		Re: Vector comparison. By: tam on Thu, 20 November 2003 10:55
		Re: Vector comparison. By: David Fanning on Thu, 20 November 2003 09:55
		Re: Vector comparison. By: Craig Markwardt on Thu, 20 November 2003 09:35
		Re: Vector comparison. By: tam on Thu, 20 November 2003 09:24
		Re: Vector comparison. By: David Fanning on Thu, 20 November 2003 08:52
		Re: Vector comparison. By: Chris[1] on Thu, 20 November 2003 08:08
		Re: Vector comparison. By: David Fanning on Thu, 20 November 2003 08:08
		Re: Vector comparison. By: R.Bauer on Thu, 20 November 2003 07:11
		Re: Vector comparison. By: tam on Thu, 20 November 2003 07:03
		Re: Vector comparison. By: hunter on Thu, 20 November 2003 06:49
		Re: Vector comparison. By: David Fanning on Thu, 20 November 2003 05:40
		Re: Vector comparison. By: R.Bauer on Thu, 20 November 2003 04:02
		Re: Vector comparison. By: Craig Markwardt on Thu, 20 November 2003 02:19
		Re: Vector comparison. By: Chris Lee on Thu, 20 November 2003 02:09
		Re: Vector comparison. By: R.Bauer on Thu, 20 November 2003 01:01
		Re: Vector comparison. By: Craig Markwardt on Thu, 20 November 2003 00:23
		Re: Vector comparison. By: David Fanning on Wed, 19 November 2003 18:05
		Re: Vector comparison. By: R.Bauer on Wed, 19 November 2003 17:50
		Re: Vector comparison. By: Craig Markwardt on Wed, 19 November 2003 15:48
		Re: Vector comparison. By: Pavel Romashkin on Wed, 19 November 2003 16:09

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