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Re: vectorising versus loops [message #38217 is a reply to message #38146]

Mon, 23 February 2004 16:04

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

nasalmon@onetel.net.uk (Neil) writes:
> Craig,
>
> yes many thanks for this valuable information. One of the problems i
> have is that the condition in the WHERE statement has to contain the
> counter in the "do loop", that is basically why i put it in the "do
> loop" to start with. Is there any way i can make the condition depend
> on the counter, ie the vector index.

Yes, you can make a vector of index values with LINDGEN,

;; Make a list of indices
ii = lindgen(n_elements(x))

;; Select on X and the index variable
wh = where(x GE 0 AND ii LT 200)

Good luck,
Craig

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[Message index]

		vectorising versus loops By: nasalmon on Sun, 22 February 2004 10:16
		Re: vectorising versus loops By: Norbert Hahn on Tue, 24 February 2004 02:13
		Re: vectorising versus loops By: Craig Markwardt on Mon, 23 February 2004 16:04
		Re: vectorising versus loops By: Craig Markwardt on Sun, 07 March 2004 09:24
		Re: vectorising versus loops By: nasalmon on Fri, 26 March 2004 11:34
		Re: vectorising versus loops By: stimmins on Mon, 12 April 2004 13:14
		Re: vectorising versus loops By: David Fanning on Fri, 26 March 2004 11:47

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