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Re: algorithm question. Can I get rid of the for loop? [message #83753 is a reply to message #83749]

Fri, 22 March 2013 06:25

Heinz Stege
Messages: 189
Registered: January 2003

Senior Member

On Thu, 21 Mar 2013 14:32:15 -0700 (PDT), Sï¿½ren Frimann wrote:

> FOR i=0,N_Elements(y)-1 DO BEGIN
> index = Where((x GE x[i] - dx) AND (x LE x[i] + dx))
> y0[i] = Median(y[index]) ; Median filtering
> s0[i] = 1.4826*Median(Abs(y[index] - y0[i])) ;estimating uncertainty
> ENDFOR

Hi Sï¿½ren,

I don't know, how to get rid of the loop. However you can make it
significantly faster, provided that the x values are monotonically
increasing:

Before entering the loop get the indices of the lower and upper limits
for all x values by use of the VALUE_LOCATE function. Then you can use
this pre-calculated indices instead of the index array from the WHERE
function.

Cheers, Heinz

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[Message index]

		Re: algorithm question. Can I get rid of the for loop? By: Jeremy Bailin on Wed, 27 March 2013 11:55
		Re: algorithm question. Can I get rid of the for loop? By: Jeremy Bailin on Wed, 27 March 2013 10:00
		Re: algorithm question. Can I get rid of the for loop? By: Jeremy Bailin on Wed, 27 March 2013 09:53
		Re: algorithm question. Can I get rid of the for loop? By: Søren Frimann on Wed, 27 March 2013 06:31
		Re: algorithm question. Can I get rid of the for loop? By: bobgstockwell on Fri, 22 March 2013 10:29
		Re: algorithm question. Can I get rid of the for loop? By: cgguido on Fri, 22 March 2013 10:01
		Re: algorithm question. Can I get rid of the for loop? By: Heinz Stege on Fri, 22 March 2013 06:25
		Re: algorithm question. Can I get rid of the for loop? By: Jeremy Bailin on Thu, 21 March 2013 20:39

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