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Re: indexing a structure in a list [message #87473 is a reply to message #87472]

Wed, 05 February 2014 09:00

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Helder writes:

> I've got the feeling this should work, but for some reason it isn't.
> So here is some code to test the problem with the errors describe in it:
>
> PRO testStrutRef
> Compile_Opt idl2
> a = list(findgen(10), /extract)
> a[4] = {value:3.0}
> help, a[4], /struct
> ;a[4].value = 4.0 ;won't work: % Attempt to store into an expression: Structure reference.
> ;(a[4]).value = 4.0 ;won't work: % Attempt to store into an expression: Structure reference.
> ;((a)[4]).value = 4.0 ;won't work: % Attempt to store into an expression: Structure reference.
> struct = a[4]
> struct.value = 4.0
> a[4] = struct ;works, but not really straight forward...
> print, a
> END
>
> It seems like I can't address a structure element of a list directly.
> Did I misplace my parenthesis? Is there a less cumbersome workaround?

Yeah, don't know. I'm no expert, but I'm not surprised lists and
structures don't play well together. Have you thought about a hash
instead?

IDL> a = list(findgen(10), /extract)
IDL> a[4] = hash('value', 3.0)
IDL> (a[4])['value'] = 4.0
IDL> print, a[4]
value: 4.00000

Cheers,

David

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

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[Message index]

		indexing a structure in a list By: Helder Marchetto on Wed, 05 February 2014 08:36
		Re: indexing a structure in a list By: David Fanning on Wed, 05 February 2014 09:00
		Re: indexing a structure in a list By: Craig Markwardt on Wed, 05 February 2014 09:52
		Re: indexing a structure in a list By: Michael Galloy on Wed, 05 February 2014 10:05
		Re: indexing a structure in a list By: Helder Marchetto on Wed, 05 February 2014 11:42

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