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RE: st: Is Stata used for spatial statistics/GIS?


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Is Stata used for spatial statistics/GIS?
Date   Thu, 19 Feb 2004 16:29:28 -0000

In addition I find in my files a program -dist-, 
which produces a dataset of distances between 
points from two variables containing Cartesian
coordinates. It's just another brute force 
solution for some isolated task. 

Nick 
n.j.cox@durham.ac.uk 

Michael Blasnik
 
> You should check out nearest.ado on SSC (by Nick Cox).  It 
> will identify the
> nearest neighbor (Euclidian distance).  I have written an 
> alternate version
> that allow a globe option (for spherical distances) and is 
> much faster on
> larger datasets (avoids brute-force N*N loop).   If you find 
> nearest too
> slow or need global distances, I can email you my program.  
> Either program
> could probably be revised to identify all observations within 
> a certain
> distance, but it is not clear how it would deal with cases 
> where there are
> many observations meeting the criteria (just list them out? 
> or create many
> added variables to hold their identities?)
> 

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