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Re: using WHERE to search for multiple values [message #30405 is a reply to message #30396]

Thu, 25 April 2002 17:05

Robert Stockwell
Messages: 74
Registered: October 2001

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)
>
>
> Sorry for the run-on nature of this post.
>
> Thanks,
> Doug
>

Hi Doug,
how about using an execute statement to call the where() a la

for i = 0,n_elements(val) do valstring = valstring + 'or val('+string(i)+')'
r = execute( 'w=where(im eq' + valstring+')')

should be ok unless there are a lot of vals.

cheers
bob

PS YAY, two execute() posts in one day.

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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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