Date:         Mon, 27 Oct 2008 14:00:47 -0400
Reply-To:     Peter Flom <peterflomconsulting@mindspring.com>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Peter Flom <peterflomconsulting@MINDSPRING.COM>
Subject:      Finding nearest neighbors
Content-Type: text/plain; charset=UTF-8

Hello

I'd like to find the nearest neighbors for each of a large number of subjects in a multivariate space.

I found PROC DISTANCE and used it as follows

<<<
proc distance data = allout out = distance;
 var interval(MAFAnT BAFAnT BRFAnT mif2f7a BAF1F7T
       BAF2F8T  BAF2F7T BAF1F7S BAF2F8S   BAF7F8S
       BFrF17S BFrF8ZS  BRFAnB  CoF7FZD MAF7T) ;
           id core;
run;
>>>>

Now, the data set "distance" has 695 variables and 694 observations.  It's a large, lower triangular matrix of distances.  The rows are CORE numbers and the columns are the same CORE numbers, preceded by a _

e.g.

Obs core     _00614D _08185C _08394B _08545A _08558A _08562A _08564A _08580A _08581A

  1 00614D    0.0000   .       .       .       .       .       .       .       .
  2 08185C   10.1968  0.0000   .       .       .       .       .       .       .
  3 08394B    6.7983 12.4716  0.0000   .       .       .       .       .       .
  4 08545A   13.0307  4.5231 16.1410  0.0000   .       .       .       .       .
  5 08558A    7.1568  8.9766  8.1237 12.4371  0.0000   .       .       .       .
  6 08562A    7.1285  4.3278  9.7992  7.3852  6.5285  0.0000   .       .       .


with many more rows and columns.

Now, I'd like to get a data set with 695 observations, and (say) 3 variables NEAREST1 NEAREST2 and NEAREST3.

I figure this must have been done before, but I didn't find it ....


Thanks

Peter

Peter L. Flom, PhD
Statistical Consultant
www DOT peterflom DOT com