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Re: Comparing 2 arrays [message #55563 is a reply to message #55562]

Sat, 25 August 2007 21:45

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

teich@atmsci.msrc.sunysb.edu writes:

> I would like to know if the data in two different 1 dimensional arrays
> are the same or not. This should be for every index. For example, if
> A=[0,1,2,3] and B=[0,1,3,2], then I would want the answer to be that A
> and B are not equal even though they happen to have the same values in
> different order. A problem with comparing each element is that the
> numbers are floating point so I would prefer not to compare with
> 'EQ'. Has anyone any suggestions?
>
> Alternatively, my arrays are actually from different structures. Is
> there a way to compare structures? For example, data1.A vs data2.B in
> the above example.

If your arrays are the same size, there is no problem using structures.
You could subtract the two values and call the result "equal" if
the difference was "sufficiently" close to zero.

IF Total( (data1.A - data2.B) LT 1e-6) EQ N_Elements(data1.A) THEN $
Print, 'The arrays are equal' ELSE Print, 'The arrays are unequal'

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: Comparing 2 arrays By: David Fanning on Mon, 27 August 2007 08:06
		Re: Comparing 2 arrays By: Conor on Mon, 27 August 2007 06:48
		Re: Comparing 2 arrays By: David Fanning on Sun, 26 August 2007 09:43
		Re: Comparing 2 arrays By: Jean H. on Sun, 26 August 2007 08:40
		Re: Comparing 2 arrays By: David Fanning on Sun, 26 August 2007 07:32
		Re: Comparing 2 arrays By: airy.jiang on Sun, 26 August 2007 02:39
		Re: Comparing 2 arrays By: teich on Sat, 25 August 2007 22:25
		Re: Comparing 2 arrays By: David Fanning on Sat, 25 August 2007 21:47
		Re: Comparing 2 arrays By: David Fanning on Sat, 25 August 2007 21:45
		Re: Comparing 2 arrays By: David Fanning on Tue, 28 August 2007 08:15
		Re: Comparing 2 arrays By: James Kuyper on Mon, 27 August 2007 10:40
		Re: Comparing 2 arrays By: Paul Van Delst[1] on Mon, 27 August 2007 10:52

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