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Re: Can this be done using array operations instead? [message #66118 is a reply to message #65921]

Thu, 02 April 2009 08:58

Juggernaut
Messages: 83
Registered: June 2008

Member

On Apr 2, 10:34 am, robintw <r.t.wil...@rmplc.co.uk> wrote:
> Hi,
>
> I'm quite new to IDL and I've written a function to calculate some
> statistics for an image file in ENVI. The function has to be
> calculated for the 3x3 square around every pixel in the image. At the
> moment I'm using a couple of nested for loops to do that - is there a
> way to do it using array operations instead?
>
> What I suppose I'm asking for is a way to call a particular function
> for every element of an array - is that possible. I know it's possible
> to do NewArray = OldArray * 2, which is calling the + function on
> every element of the array, but is there a way to call my user-defined
> function on each element?
>
> I can post code if that would help.
>
> Cheers,
>
> Robin

I don't know exactly what "function" you're wanting to perform on
these pixels but CONVOL will operate in such a way.
IDL> x = indgen(3,3)
IDL> print, convol(x, [[1,1,1],[1,0,1],[1,1,1]], /center)
0 0 0
0 32 0
0 0 0

This will add up the surrounding pixels giving you the value as the
new center pixel...don't know if that's helpful but enjoy.

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[Message index]

		Can this be done using array operations instead? By: robintw on Thu, 02 April 2009 07:34
		Re: Can this be done using array operations instead? By: Jeremy Bailin on Thu, 02 April 2009 14:11
		Re: Can this be done using array operations instead? By: robintw on Thu, 02 April 2009 12:43
		Re: Can this be done using array operations instead? By: robintw on Thu, 02 April 2009 11:58
		Re: Can this be done using array operations instead? By: Jean H. on Thu, 02 April 2009 11:39
		Re: Can this be done using array operations instead? By: robintw on Thu, 02 April 2009 10:38
		Re: Can this be done using array operations instead? By: Allan Whiteford on Thu, 02 April 2009 10:16
		Re: Can this be done using array operations instead? By: robintw on Thu, 02 April 2009 09:26
		Re: Can this be done using array operations instead? By: Juggernaut on Thu, 02 April 2009 08:58

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