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Re: Reversing a multi-dimensional array [message #35606 is a reply to message #35591]

Thu, 03 July 2003 17:06

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

"Andy Loughe ( remove OMITs )" <Andrew.LougheOMIT@noaaOMIT.govOMIT> writes:
> Hello,
>
> I have a 4-dimensional array, but it could someday grow to become
> 6 or 7 dimensions. What I would like to do is reverse the entire
> array, so that if it is now: a(i,j,k,l) it becomes a(l,k,j,i).
>
> What is the most efficient method for accomplishing this in IDL?

Greetings--

I think you don't actually want to reverse the array, but rather
change the order of the dimensions. This is exactly what TRANSPOSE
will do for you with its mysterious optional permutation vector
parameter. Explaining it is much harder than showing how you would
use it:

aprime = transpose(a, [3,2,1,0])

(which is actually the default). Unfortunately this is a case where
RSI used 0-based dimension numbering instead of 1-based (as is used in
TOTAL, MIN etc).

Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: Reversing a multi-dimensional array By: Dick Jackson on Mon, 07 July 2003 09:30
		Re: Reversing a multi-dimensional array By: Craig Markwardt on Thu, 03 July 2003 17:06
		Re: Reversing a multi-dimensional array By: David Fanning on Thu, 03 July 2003 16:59

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