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Re: slow processing of my k-nearest neighour code [message #49786 is a reply to message #49785]

Mon, 14 August 2006 07:11

btt
Messages: 345
Registered: December 2000

Senior Member

humphreymurray@gmail.com wrote:

>> ; Calculate the squared distance for each attribute.
>> squared = make_array(num_training_elements, num_attributes)
>> for attrib = 0, num_attributes-1 do begin
>> squared[*,attrib] = (testing_data[i, attrib] -
>> training_data[*,attrib])^2
>> endfor
>>

Hi,

You might try replacing the above for inner-loop with the following

squared = (testing_data - training_data)^2

Since IDL is array saavy it will perform the operation element by
element for you quite quickly (as well as make the "squared" array for you).

You might be able to eliminate the outer-loop, too, but I am less sure
of that. Take a peek at the for-loop bible at

http://www.dfanning.com/tips/forloops.html

Good luck,
Ben

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[Message index]

		Re: slow processing of my k-nearest neighour code By: James Kuyper on Tue, 15 August 2006 08:14
		Re: slow processing of my k-nearest neighour code By: humphreymurray on Mon, 14 August 2006 19:17
		Re: slow processing of my k-nearest neighour code By: humphreymurray on Mon, 14 August 2006 19:07
		Re: slow processing of my k-nearest neighour code By: JD Smith on Mon, 14 August 2006 14:39
		Re: slow processing of my k-nearest neighour code By: James Kuyper on Mon, 14 August 2006 13:50
		Re: slow processing of my k-nearest neighour code By: btt on Mon, 14 August 2006 09:01
		Re: slow processing of my k-nearest neighour code By: news.verizon.net on Mon, 14 August 2006 08:30
		Re: slow processing of my k-nearest neighour code By: Karl Schultz on Mon, 14 August 2006 08:08
		Re: slow processing of my k-nearest neighour code By: btt on Mon, 14 August 2006 07:11
		Re: slow processing of my k-nearest neighour code By: humphreymurray on Mon, 14 August 2006 06:50

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