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Re: Multi bands mean [message #58662 is a reply to message #58661]

Fri, 08 February 2008 09:05

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

jujo@argentina.com writes:

> I have a multi-bands image. I need to calculate the mean value of each
> pixel, considering all the bands. It can be easily done using:
>
> mean_image=total(multi_bands_image, 3) / number of bands
>
> However, I have some nan values, which have to be discarded before the
> calculation. I can do that:
>
> mean_image=total(multi_bands_image, 3, /nan) / number of bands
>
> However, if I do that, the nan values become zeros and the average
> includes them. How can I do to calculate the mean without considering
> nan values?

Seems to me you want this:

mean_image=total(multi_bands_image, 3, /nan) / total(finite(a),3)

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: Multi bands mean By: jujo on Fri, 08 February 2008 09:44
		Re: Multi bands mean By: David Fanning on Fri, 08 February 2008 09:15
		Re: Multi bands mean By: David Fanning on Fri, 08 February 2008 09:09
		Re: Multi bands mean By: David Fanning on Fri, 08 February 2008 09:05

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