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Re: Randomize array order [message #55012 is a reply to message #55011]

Thu, 26 July 2007 09:57

David Streutker
Messages: 34
Registered: June 2005

Member

How about a Knuth shuffle?

(Disclaimer: I'm not a statistician; I just found it on Wikipedia.)

function kunsort, array
na = n_elements(array)
random = randomu(seed,na) * (na - array - 1) + array
for i=0L,na-2 do array[i] = array[random[i]]
return, array
end

Added to Vince's code (last column):

0 100000 0.0619998 0.0780001 0.0320001
1 166810 0.125000 0.125000 0.0780001
2 278256 0.282000 0.218000 0.141000
3 464158 0.547000 0.406000 0.235000
4 774263 1.07800 0.657000 0.390000
5 1291549 1.93700 1.09400 0.703000
6 2154435 3.51500 1.89100 1.20300
7 3593812 6.34400 3.11000 1.98400
8 5994841 11.5470 5.21800 3.36000
9 10000000 20.3750 8.67200 5.60900

Windows XP, dual 2.66 GHz, 3 GB RAM, IDL 6.3

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[Message index]

		Re: Randomize array order By: Michael Galloy on Fri, 27 July 2007 15:35
		Re: Randomize array order By: James Kuyper on Fri, 27 July 2007 14:29
		Re: Randomize array order By: Conor on Fri, 27 July 2007 11:09
		Re: Randomize array order By: David Streutker on Fri, 27 July 2007 10:54
		Re: Randomize array order By: Conor on Fri, 27 July 2007 09:44
		Re: Randomize array order By: James Kuyper on Fri, 27 July 2007 09:29
		Re: Randomize array order By: James Kuyper on Fri, 27 July 2007 09:05
		Re: Randomize array order By: David Streutker on Fri, 27 July 2007 07:54
		Re: Randomize array order By: Paolo Grigis on Fri, 27 July 2007 06:59
		Re: Randomize array order By: Allan Whiteford on Fri, 27 July 2007 05:03
		Re: Randomize array order By: Allan Whiteford on Fri, 27 July 2007 02:33
		Re: Randomize array order By: David Streutker on Thu, 26 July 2007 14:27
		Re: Randomize array order By: Vince Hradil on Thu, 26 July 2007 13:32
		Re: Randomize array order By: David Streutker on Thu, 26 July 2007 09:57
		Re: Randomize array order By: Conor on Thu, 26 July 2007 09:22
		Re: Randomize array order By: Allan Whiteford on Thu, 26 July 2007 08:49
		Re: Randomize array order By: Vince Hradil on Thu, 26 July 2007 08:13
		Re: Randomize array order By: Vince Hradil on Thu, 26 July 2007 07:58
		Re: Randomize array order By: Conor on Thu, 26 July 2007 06:40
		Re: Randomize array order By: Allan Whiteford on Thu, 26 July 2007 06:30
		Re: Randomize array order By: Brian Larsen on Thu, 26 July 2007 06:06
		Re: Randomize array order By: Brian Larsen on Thu, 26 July 2007 06:04
		Re: Randomize array order By: mattf on Thu, 26 July 2007 05:50
		Re: Randomize array order By: Conor on Thu, 26 July 2007 05:28
		Re: Randomize array order By: Conor on Thu, 26 July 2007 05:24
		Re: Randomize array order By: Vince Hradil on Wed, 25 July 2007 12:59

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