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Re: fast array comparison [message #33150 is a reply to message #33149]

Mon, 09 December 2002 07:48

Sean Raffuse
Messages: 46
Registered: July 2001

Member

I apologize for my inexperience. Gusenet?

"JD Smith" <jdsmith@as.arizona.edu> wrote in message
news:pan.2002.12.09.15.25.07.822280.6387@as.arizona.edu...
> On Sun, 08 Dec 2002 18:39:23 -0700, Craig Markwardt wrote:
>
>> "Sean Raffuse" <sean@me.wustl.edu> writes:
>>> David,
>>>
>>> Thanks for this. It works almost perfectly. I am a little confused
>>> though. It seems that the indices keyword returns the indices of the
>>> requested array and not the available array.
>>
>> Greetings Sean--
>>
>> Another option is CMSET_OP from my web page. It uses the HISTOGRAM
>> technique, if the dynamic range of values is small, but graduates to a
>> different, sort/uniq-based method, if the dynamic range is large.
>> Indices can be returned using the /INDEX keyword. [ In case it isn't
>> obvious, you want to use the 'AND' operation. ]
>>
>> CMSET_OP also returns indices from the *first* array. This is not a
>> problem for your application, since you can simply swap the positions of
>> the first and second arrays in the function call.
>>
>> Yours,
>> Craig
>>
>> http://cow.physics.wisc.edu/~craigm/idl/idl.html (under Array/Set Ops)
>
> This topic was discussed ad naseum over the past couple of years, with
> the critical differences between looking for the values and looking for
> the indices of intersection pointed out. Several different methods were
> compared using HISTOGRAM, SORT, and direct array inflation. Depending on
> your problem size, one of these will be fastest. Usually. ;).
>
> Give it a search on Gusenet.
>
> JD

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[Message index]

		Re: fast array comparison By: JD Smith on Mon, 09 December 2002 09:59
		Re: fast array comparison By: David Fanning on Mon, 09 December 2002 08:07
		Re: fast array comparison By: David Fanning on Mon, 09 December 2002 08:00
		Re: fast array comparison By: Sean Raffuse on Mon, 09 December 2002 07:48
		Re: fast array comparison By: JD Smith on Mon, 09 December 2002 07:25
		Re: fast array comparison By: Sean Raffuse on Mon, 09 December 2002 07:24
		Re: fast array comparison By: Craig Markwardt on Sun, 08 December 2002 17:39
		Re: fast array comparison By: David Fanning on Sun, 08 December 2002 12:47
		Re: fast array comparison By: David Fanning on Sun, 08 December 2002 12:40
		Re: fast array comparison By: Sean Raffuse on Sun, 08 December 2002 12:35
		Re: fast array comparison By: Sean Raffuse on Sun, 08 December 2002 12:32
		Re: fast array comparison By: David Fanning on Sun, 08 December 2002 09:45

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