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Re: using WHERE to search for multiple values [message #30391]

Fri, 26 April 2002 09:05

Pavel A. Romashkin
Messages: 531
Registered: November 2000

Senior Member

Oh boy. It looks to me that the poster in fact wanted to avoid looping
through every element of the array.
Why not try SET_INTERSECTION or what is it called, from David's web
site? The one, real fast, that uses HISTOGRAM?
No loops at all. And you can get either the elements that match or the indices.
Good luck,
Pavel

Doug Martin wrote:
>
> I'm trying to do something like the following:
>
> w=where(im eq val)
>
> with im a byte array (say, 640x480)
> and val an array (say, 10 to 40 long)
>
> I want to find where im is equal to _any_ of the values in val. But,
> val is not always the same size.
>
> Is there a way to do this using one WHERE call? There seems to be a
> giant time difference between:
>
> for i=0,(size(val))[1]-1 do begin
> w=where(im eq val(i))
> ...
> endfor
>
> and
>
> w=where(im eq val(0) or val(1) or val(2) or ...)
>
> (but I can't do the above since val has different sizes from call to
> call)
>
> Sorry for the run-on nature of this post.
>
> Thanks,
> Doug

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[Message index]

		Re: using WHERE to search for multiple values By: Pavel A. Romashkin on Fri, 26 April 2002 09:05
		Re: using WHERE to search for multiple values By: Jonathan Joseph on Fri, 26 April 2002 08:31
		Re: using WHERE to search for multiple values By: James Kuyper on Fri, 26 April 2002 05:15
		Re: using WHERE to search for multiple values By: Paul Van Delst[1] on Fri, 26 April 2002 06:08
		Re: using WHERE to search for multiple values By: Robert Stockwell on Thu, 25 April 2002 17:05

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