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Re: How to get matching elements of array efficiently [message #69928 is a reply to message #69926]

Wed, 24 February 2010 00:54

rogass
Messages: 200
Registered: April 2008

Senior Member

On 23 Feb., 21:11, JJ <j...@cornell.edu> wrote:
> Hi All,
>
> I'm looking for an efficient (non-loop) solution to this problem. I
> have two arrays A, B. The elements of A are not necessarily unique,
> nor is A necessarily sorted. I'd like to find all the indices in A
> that match values that occur in B.
>
> For example, if A = [7,1,8,7,8], B = [7,8], the result should be
> [0,2,3,4].
>
> A and B can have many (order millions) of unique values, so I'd rather
> avoid a loop if I can.
>
> Is there any way to do this efficiently?
>
> Thanks.
>
> -JJ

Hi,
I don't know the other solutions, but maybe this one will also work
for you :)

wh = where(total(((c=abs(rebin(transpose(a[*]),$
((nb=n_elements(b))),((na=n_elements(a))),/sample) - $
rebin(b[*],nb,na,/sample)))) eq 0,1))

Cheers

CR

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[Message index]

		Re: How to get matching elements of array efficiently By: JJ on Mon, 01 March 2010 11:18
		Re: How to get matching elements of array efficiently By: JJ on Mon, 01 March 2010 10:58
		Re: How to get matching elements of array efficiently By: JDS on Wed, 24 February 2010 14:26
		Re: How to get matching elements of array efficiently By: Jeremy Bailin on Wed, 24 February 2010 06:46
		Re: How to get matching elements of array efficiently By: rogass on Wed, 24 February 2010 00:54
		Re: How to get matching elements of array efficiently By: wlandsman on Tue, 23 February 2010 13:06
		Re: How to get matching elements of array efficiently By: penteado on Tue, 23 February 2010 12:36

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