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Re: IDL-way to use WHERE result as subscripting indices without having to do IF count [message #76183 is a reply to message #76180]

Fri, 20 May 2011 06:27

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

David Fanning writes:

> Or, if in IDL 8, set the NULL keyword to the Where
> function:
>
> IDL> a=[1,2]
> IDL> help, where(a lt 0)
> <Expression> LONG = -1
> IDL> help, where(a lt 0, /null)
> <Expression> UNDEFINED = !NULL
> IDL> c=a[where(a lt 0, /NULL)]

By the way, if you are writing code that there
is any chance someone else might use, you have
to wait at least two years or two major releases
of IDL, whichever is longer, before you can
use any new feature in a program.

If you do it too soon, your life will become
a nightmare of support issues. :-)

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: IDL-way to use WHERE result as subscripting indices without having to do IF count By: Heinz Stege on Fri, 20 May 2011 08:22
		Re: IDL-way to use WHERE result as subscripting indices without having to do IF count By: David Fanning on Fri, 20 May 2011 06:27
		Re: IDL-way to use WHERE result as subscripting indices without having to do IF count By: David Fanning on Fri, 20 May 2011 06:19
		Re: IDL-way to use WHERE result as subscripting indices without having to do IF count By: Robin Wilson on Fri, 20 May 2011 06:18
		Re: IDL-way to use WHERE result as subscripting indices without having to do IF count By: penteado on Fri, 20 May 2011 06:16

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