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Re: Faster way ? [message #41172 is a reply to message #41171]

Mon, 27 September 2004 13:46

Dick Jackson
Messages: 347
Registered: August 1998

Senior Member

"Craig Markwardt" <craigmnet@REMOVEcow.physics.wisc.edu> wrote in message
news:onr7onip35.fsf@cow.physics.wisc.edu...
> rats@mail.geog.uvic.ca (Rafael Loos) writes:
>> Hi, I am trying to find the number of values that are within a range
>> ...
>> I have an Array that has 3 columns and 5 millions lines.
>> Thats what I am doing ...
>>
>> number = WHERE((Array[1,*] GE Min) AND (Array[1,*] LE Max), geralX)
>>
>> I am storing the number inside the variable geralX ...
>> It is taking 0.23 seconds ... but I want to know if there is a faster
>> way to find that ...
>
> If you are doing this many times in a loop and ARRAY is unchanging, it
> may be worth extracting ARRAY[1,*] into its own variable. That way,
> you will save the time of extracting each iteration.
>
> If you just want the total number of elements that match your filter,
> you can use total, as in:
>
> filter = (Array[1,*] GE Min) AND (Array[1,*] LE Max)
> geralX = total(filter)

Even with the two uses of Array[1,*], I got 30-40% time reduction with this:

array1 = Array[1,*]
number = WHERE((Array1 GE Min) AND (Array1 LE Max), geralX)

... and then splicing in your method gave a total of about 45% time
reduction:

array1 = Array[1,*]
geralX = Total((Array1 GE Min) AND (Array1 LE Max))

Hope this helps!

Cheers,
--
-Dick

Dick Jackson / dick@d-jackson.com
D-Jackson Software Consulting / http://www.d-jackson.com
Calgary, Alberta, Canada / +1-403-242-7398 / Fax: 241-7392

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[Message index]

		Re: Faster way ? By: btt on Tue, 28 September 2004 09:05
		Re: Faster way ? By: JD Smith on Tue, 28 September 2004 08:49
		Re: Faster way ? By: btt on Mon, 27 September 2004 14:12
		Re: Faster way ? By: Dick Jackson on Mon, 27 September 2004 13:46
		Re: Faster way ? By: Craig Markwardt on Mon, 27 September 2004 10:44

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