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Re: rebin and !values.f_nan [message #54879 is a reply to message #54878]

Sun, 15 July 2007 21:17

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

kuyper writes:

> I've been at home this weekend, without access to IDL, so I hadn't
> gotten around to testing it. However, what Nick diescribed was not the
> creation of data where none exists, but the destruction of usable data
> by rebin():
>
>> If I use Rebin and there is a NaN value, new array becomes also NaN.
>
> I understood that to mean that the entire re-binned array was set to
> NaN, not just isolated portions of it.

His example showed an entire vector, one element of which was
a NAN, reduced to a single value. In this case, the result--
sensibly I think, since it WAS involved in the calculation--
was a NAN. In the example, the mean was probably a better
choice for a single number (and you can set a NAN flag for
that), but for some reason the requester rejected that as
an option. (He didn't explain why.)

My only point is that if you are going to assign a
value where one didn't exist before, you will have to
take responsibility for doing so. IDL can hardly be
expected to help you out in this ethically challenging
situation. I think it is right that any expression that
involves a NAN will result in a NAN. What else could
it be. :-)

Cheers,

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

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[Message index]

		Re: rebin and !values.f_nan By: Dick Jackson on Mon, 16 July 2007 00:03
		Re: rebin and !values.f_nan By: David Fanning on Sun, 15 July 2007 21:17
		Re: rebin and !values.f_nan By: James Kuyper on Sun, 15 July 2007 21:04
		Re: rebin and !values.f_nan By: David Fanning on Sun, 15 July 2007 18:59
		Re: rebin and !values.f_nan By: James Kuyper on Sun, 15 July 2007 18:42
		Re: rebin and !values.f_nan By: David Fanning on Sun, 15 July 2007 15:13
		Re: rebin and !values.f_nan By: Nick[1] on Sun, 15 July 2007 14:20
		Re: rebin and !values.f_nan By: David Fanning on Sun, 15 July 2007 09:20

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