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Re: fastest way to find the first non-zero value in an array [message #59672 is a reply to message #59671]

Tue, 08 April 2008 06:56

Spon
Messages: 178
Registered: September 2007

Senior Member

On Apr 8, 2:15 pm, Vince Hradil <hrad...@yahoo.com> wrote:
> On Apr 8, 3:04 am, smas...@locean-ipsl.upmc.fr wrote:
>
>> Hi,
>
>> I want to find the first non-zero value of an array. Is there a faster
>> way to do this than with the "where" command: (where(array ne 0))[0]
>> "Where" will look for all non-zero values and I only need the first
>> one. It would be great if I could stop "where" in its search process
>> as soon as it found one element...
>
>> sebastien
>
> Wow - I'd be interested in knowing how slow 'where' is. Are we
> talking the difference between 0.01 seconds and 0.05 seconds? Or even
> the difference between 1 and 5 seconds? Time is money, but at what
> point does our 'need for speed' end?

You make a good point, Vince.

If anyone can find an array that IDL actually searches faster using my
Histogram-and-small-Where setup than by using "Where" on its own, let
me know! :-)

Chris

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[Message index]

		Re: fastest way to find the first non-zero value in an array By: Vince Hradil on Tue, 08 April 2008 07:02
		Re: fastest way to find the first non-zero value in an array By: Spon on Tue, 08 April 2008 06:56
		Re: fastest way to find the first non-zero value in an array By: David Fanning on Tue, 08 April 2008 06:34
		Re: fastest way to find the first non-zero value in an array By: Vince Hradil on Tue, 08 April 2008 06:15
		Re: fastest way to find the first non-zero value in an array By: Spon on Tue, 08 April 2008 06:03
		Re: fastest way to find the first non-zero value in an array By: Clemens on Tue, 08 April 2008 01:42
		Re: fastest way to find the first non-zero value in an array By: karo03de on Wed, 09 April 2008 13:02

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