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Re: Complementary set. [message #12935]

Thu, 24 September 1998 00:00

David Kastrup
Messages: 33
Registered: February 1998

Member

Imanol Echave <ccaeccai@sc.ehu.es> writes:

> Hi people:
>
> I want to eliminate certain elements from an array. I've the index of the
> elements to be erased, and I want to obtain the "complementary" index (with the
> elements to maintain) to do new_array=array[index]. I can do this with a FOR
> loop, but... ï¿½is it a better way?

Assume that the array size is in sz, and the indices in ind. Assume
that ind is non-empty. Then

invind = replicate(1,sz)
invind[ind] = 0
invind=where(invind)

does the trick in O(n) time.

--
David Kastrup Phone: +49-234-700-5570
Email: dak@neuroinformatik.ruhr-uni-bochum.de Fax: +49-234-709-4209
Institut fï¿½r Neuroinformatik, Universitï¿½tsstr. 150, 44780 Bochum, Germany

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		Re: Complementary set. By: David Kastrup on Thu, 24 September 1998 00:00
		Re: Complementary set. By: Martin Schultz on Tue, 22 September 1998 00:00

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