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Re: uniq slow for loop [message #67269 is a reply to message #67263]

Thu, 16 July 2009 18:40

ben.bighair
Messages: 221
Registered: April 2007

Senior Member

On Jul 16, 5:52 pm, newerjazz <shang...@gmail.com> wrote:
> Hi All,
>
> I have an array of [9,1,000,000]. In one of the columns are sorted
> numbers (eg. 0,1,1,2,3,3,3,3,3,4,4,5,5,5,6,7,7,7,etc). I want to pick
> out all the rows where column 9 is equal to some number and average
> all the quantities in those rows.
>
> Right now I use a for loop and the where function to pick out these
> rows. This is of course very slow. Anyway to increase the speed of
> this would be greatly appreciated. Thank you very much!
>
> Cheers,
> newerjazz
>
> nmax = max(data(8,*))
> FOR j=0, nmax DO BEGIN
> w=where(data(8,*) eq j, nw)
> blah=mean(data(*,w))
> etc,etc
> ENDFOR

Hi,

I am pretty sure that you want a variant of histogram. I think you
might be able to harness something from the following discussion.

http://tinyurl.com/nggcx6

Cheers,
Ben

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		Re: uniq slow for loop By: newerjazz on Fri, 17 July 2009 08:59
		Re: uniq slow for loop By: ben.bighair on Thu, 16 July 2009 18:40

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