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Re: using WHERE to search for multiple values [message #30396 is a reply to message #30394]

Fri, 26 April 2002 05:15

James Kuyper
Messages: 425
Registered: March 2000

Senior Member

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)

mask = where(im ne im)
for i=0, count=(size(val))[1]-1 do begin
mask = mask OR (im eq val[i])
endfor
w = where(mask)

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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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