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Re: behavior of arrays [message #15572 is a reply to message #15435]

Thu, 20 May 1999 00:00

David Kastrup
Messages: 33
Registered: February 1998

Member

Jack Saba <jack@icesat1.gsfc.nasa.gov> writes:

> But more often than not, I WANT the extra dimension to be lost,
> or at least I want IDL to be willing to ignore it where appropriate.
> Consider this unrealistic example that nevertheless illustrates a
> problem that occurs all too often in IDL:
>
> IDL> x=findgen(100)
> IDL> ijk=where(x eq 10)
> IDL> for i=ijk,99 do print, i
> % Expression must be a scalar in this context: I.
> % Execution halted at: $MAIN$
>
> I could have written i=ijk[0],99, or i=REFORM(ijk),99 to avoid the
> error. But it shouldn't be necessary -- this should be handled
> transparently.

It is handled transparently. If you want a scalar, write ijk[0].
This works even where ijk is *indeed* a scalar.

This is, BTW, about the only way to check for the result of "where" in a
useful way:
w = where(x)
if (w[0] lt 0)
...

--
David Kastrup Phone: +49-234-700-5570
Email: dak@neuroinformatik.ruhr-uni-bochum.de Fax: +49-234-709-4209
Institut fï¿½r Neuroinformatik, Universitï¿½tsstr. 150, 44780 Bochum, Germany

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[Message index]

		behavior of arrays By: R.Bauer on Wed, 19 May 1999 00:00
		Re: behavior of arrays By: thompson on Fri, 21 May 1999 00:00
		Re: behavior of arrays By: Mark Fardal on Fri, 21 May 1999 00:00
		Re: behavior of arrays By: Justin Ashmall on Thu, 20 May 1999 00:00
		Re: behavior of arrays By: Jack Saba on Thu, 20 May 1999 00:00
		Re: behavior of arrays By: Martin Schultz on Thu, 20 May 1999 00:00
		Re: behavior of arrays By: David Kastrup on Thu, 20 May 1999 00:00
		Re: behavior of arrays By: Jack Saba on Thu, 20 May 1999 00:00
		Re: behavior of arrays By: R.Bauer on Thu, 20 May 1999 00:00

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