| Re: Arrays in structures; workarounds? [message #20132 is a reply to message #19967] |
Mon, 22 May 2000 00:00   |
Martin Schultz
Messages: 515
Registered: August 1997
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Senior Member |
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... although I agree with most of you that chopping of dimensions bears
more risks than virtues, here is an easy workaround:
help,
gives you the array back ;-)
Cheers,
Martin
Craig Markwardt wrote:
>
> We've seen this one before, but it still astounds me that it stays
> around from version to version of IDL.
>
> IDL routinely drops the last dimension if the length is 1. We know
> that and can deal with it for the most part. For example, we can
> ensure the dimensions by REFORMing the array. The thing that gets me
> is when a structure element is a one-element array, like this:
>
> IDL> z1 = {x:reform(dblarr(1,1),1,1)}
> IDL> help, /struct, z1
> ** Structure <40047208>, 1 tags, length=8, refs=1:
> X DOUBLE Array
>
> Sure enough, it's a 1x1 element array, containing just one value of
> course. But when you try to extract that element, it comes out like
> this:
>
> IDL> help, z1.x
> <Expression> DOUBLE = 0.0000000
>
> Huh? A scalar? This is worse than IDL dropping the last dimensions.
> It's dropping *all* the dimensions. This can be a problem, if for
> example, you will be passing the value to PLOT, which takes only
> arrays. And it aggravates me to h*ll!
>
> Does anybody know a way to work around this? I've thought of some
> pretty wierd things to try, like passing the struct as _EXTRA. The
> only thing I can come up with is to parse the result of HELP,
> OUTPUT=out, but that seems like the crappiest solution ever.
>
> Any ideas?
>
> Craig
>
> P.S. ... and it goes without saying that I don't necessarily know the
> tag name ahead of time.
>
> P.P.S.
> IDL> print, !version
> { alpha OSF unix 5.2 Oct 30 1998}
>
> --
> ------------------------------------------------------------ --------------
> Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
> Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
> ------------------------------------------------------------ --------------
--
[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[ [[[[[[[
[[ Dr. Martin Schultz Max-Planck-Institut fuer Meteorologie [[
[[ Bundesstr. 55, 20146 Hamburg [[
[[ phone: +49 40 41173-308 [[
[[ fax: +49 40 41173-298 [[
[[ martin.schultz@dkrz.de [[
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