-nearest- on SSC has relevant (pre-Mata) code.
I thought Michael Blasnik had written something more efficient but I
can't find it or -findit- quickly.
Nick
[email protected]
Nick Cox
By the way, hasn't this been done before?
Nick
[email protected]
Susan Olivia
Can I get programming advice how to create a NxN distance
matrix using the information on latitude and longitude.
Below is what I attempted to do in STATA, but it didn't
work. Would be great if I can get any advice on how to
improve this code.
****************************
qui set obs 1000
gen xcoord = uniform()*100
gen ycoord = uniform()*100
mkmat xcoord ycoord
local N=_N
scalar N = _N
matrix latlong= xcoord,ycoord
matrix D = J(`N',`N', 0)
* looping through the rows and columns of the matrix D, to
get distance pair for each observations
for(i = 1; i <=N; i++) {
for(j = 1; j<=N; j++) {
if (i!=j){
D[i,j]=
((xcoord[i]-xcoord[j]^2+(ycoord[i]-ycoord[j]^2)^0.5
}
}
}
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
