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Re: Can I de-loop?
- Subject: Re: Can I de-loop?
- From: eddie haskell <haskell(at)see.signature.edu>
- Date: Thu, 15 Jul 1999 09:14:54 -0400
- Newsgroups: comp.lang.idl-pvwave
- Organization: Old Dominion Universityaruba
- References: <email@example.com>
- Xref: news.doit.wisc.edu comp.lang.idl-pvwave:15685
I have a suggestion for the first of your quandries:
> a) I am adding a constant amount K to several elements N of array A.
> The elements Ni are not unique; if an Ni is repeated, I want to add it
> to A each time. For instance, given
> A = [0,1,2]
> N = [2,2,2]
> K = 4
> I want the result A = [0,1,14], not A = [0,1,6]
IDL> A[min(N):max(N)] = A[min(N):max(N)] + K*histogram(N)
0 1 14
This seems to be at least twice as fast as the loop with the time
difference increasing as the number of elements in A and N increase, at
least for the values I played around with ( up to 100,000 elements).
You should check this thread later as I should point out that over 95%
of my suggestions to this newsgroup do not end up helping the original
question. Either my solution is too specific for the problem or someone
else soon posts a better solution. I hope for the latter as I can also
learn something that way.
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|\ A G Edward Haskell
|\ Center for Coastal Physical Oceanography
|\ Old Dominion University, Norfolk VA 23529
|\ Voice 757.683.4816 Fax 757.683.5550
|\ e-mail haskell*ccpo.odu.edu
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