st: Vincenty question

[David Torres <torresd@umich.edu>]

I'm was originally calculating distances from census tract centroids  
to nearest postsecondary institution.  Secondary to this, I also  
created a variable to just list the number of schools within a certain  
radius of the tract centroids.  Everything works superbly and I thank  
Austin and Nick for their help.

Now I need to be able to list all distances from tracts to schools as  
well as the IDs for the schools that are within the distance I've  
given for my radius.  That is, I'd like to have the school that is  
nearest to a tract listed first, followed successively by the next  
closest school, and so on, within the the radius in my command.  I've  
included a piece of the code that I have for doing this for ONLY the  
minimum distance.  I appreciate any help y'all can give.

code excerpt:

g long rad10=.
g double dist1=.
g id1=""
merge using univpoints00_0

forv i=1/`np' {
qui vincenty `=latitude[`i']' `=longitude[`i']' sch_lat sch_lon, hav(dis)
g within10=dis<10
su within10, meanonly
qui replace rad10=r(sum) in `i'
su dis, meanonly
qui replace dist1=r(min) in `i'
qui levelsof unitid if dis==dist1[`i'], loc(vs)
foreach v of loc vs {
 qui replace id1="`v' "+id1 in `i'
  }
drop dis within10
}

end excerpt


David Torres

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