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Re: Can I de-loop? [message #16302 is a reply to message #16298]

Thu, 15 July 1999 00:00

eddie haskell
Messages: 29
Registered: September 1998

Junior Member

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)
IDL> print,A
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.

Cheers,
eddie

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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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[Message index]

		Re: Can I de-loop? By: eddie haskell on Thu, 15 July 1999 00:00
		Re: Can I de-loop? By: davidf on Thu, 15 July 1999 00:00
		Re: Can I de-loop? By: eddie haskell on Thu, 15 July 1999 00:00
		Re: Can I de-loop? By: R.G. Stockwell on Thu, 15 July 1999 00:00

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