Re: nearest neighbor

*To*: mathgroup at smc.vnet.net*Subject*: [mg66106] Re: [mg66075] nearest neighbor*From*: "Simons, F.H." <F.H.Simons at tue.nl>*Date*: Sat, 29 Apr 2006 03:41:11 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Chris, It is an interesing question how to find the nearest neighbor without computing ALL distances. But I would not be surprised if such a solution turns out to be slower than computing all distances, e.g. in the following way. Finding the nearest neighbor from a set of 10^6 points takes less than 0.4 second on my slow computer here at the university. p = {2, 1, 3}; mat = Array[Random[Real, {0, 4}] & , {10^6, 3}]; Extract[mat, Ordering[ Total[(Transpose[mat] - p)^2], 1]] // Timing {0.361 Second, {1.97792, 0.982634, 2.98964}} Regards, Fred Simons Eindhoven University of Technology > -----Original Message----- > From: Kulp, Chris [mailto:Chris.Kulp at EKU.EDU] To: mathgroup at smc.vnet.net > Subject: [mg66106] [mg66075] nearest neighbor > > > Hello: > > I am in interested in finding the nearest neighbor for points > in a space whose dimension is greater than two. How can I do > this in Mathematica without computing the distances between > all of the points? In particular, I am interested in > developing a Mathematica notebook for the false nearest > neighbor algorithm used in nonlinear time series analysis. > > > > > Thank you for any help you can give to me. > > > > Chris Kulp > > > > Dr. Christopher W. Kulp, Ph.D. > > Assistant Professor of Physics > > Eastern Kentucky University > > Moore 351 > > 521 Lancaster Ave. > > Richmond, KY 40475 > > 859.622.1528 > > chris.kulp at eku.edu > > http://people.eku.edu/kulpc > > > >