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Re: Efficient pattern-matching in a large array [message #77296 is a reply to message #77218]

Wed, 17 August 2011 14:14

Bob[4]
Messages: 24
Registered: April 2009

Junior Member

This is nice but it would seem an incorrect use of keyword_set(w) in the while statement? If the where statement returns [0] (a possibly valid match) then the while statement will not run. Thus one of the standard approaches for detecting a successful where is needed (i.e., check that count gt 0 or pat[0] gt -1 w/o the /NULL).

ASIDE: IDL does not let you subscript a !null variable as a length one array.

IDL> a = !NULL
IDL> print, a[0]
% Variable is undefined: A.
% Execution halted at: $MAIN$

Why not? Seems to me it should print !NULL. This would be occasionally useful, although it would not help with the above problem.

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[Message index]

		Efficient pattern-matching in a large array By: Chris O'Dell on Tue, 02 August 2011 11:05
		Re: Efficient pattern-matching in a large array By: Foldy Lajos on Tue, 02 August 2011 13:04
		Re: Efficient pattern-matching in a large array By: ez569x on Fri, 12 August 2011 05:18
		Re: Efficient pattern-matching in a large array By: Brian Daniel on Fri, 12 August 2011 07:38
		Re: Efficient pattern-matching in a large array By: guillermo.castilla.ca on Tue, 16 August 2011 09:41
		Re: Efficient pattern-matching in a large array By: guillermo.castilla.ca on Wed, 17 August 2011 06:41
		Re: Efficient pattern-matching in a large array By: JDS on Tue, 16 August 2011 16:01
		Re: Efficient pattern-matching in a large array By: Bob[4] on Wed, 17 August 2011 14:14
		Re: Efficient pattern-matching in a large array By: JDS on Thu, 18 August 2011 10:00

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