st: calculate pairwise distance between tracts

[sara borelli <saraborelli77@yahoo.it>]

Dear statalister
I am trying to calcluate pariwise distance between census tracts whithin state. I have longitude and latitude for each tract and I know vincenty command calculate distance
However, I am having sme troubles to organize data in the appropriate way to apply the command

suppose I have
tract
1
2
3

if I put the data in the form

tract_orgin	tract_Dest   long_orig    long_dest  lat_orig    lat_dest
1		1
1		2
1		3
2		1
2		2
2		3
3		1
3		2
3		3

 if I organize the data in this way I can apply 
vincety (lat_orig long_orig lat_dest long_dest) whihc gives me distance between any 2 tracts

the problem is that I am having hard time to organize the data in that format given the large number of census tracts

any suggestion on how to do this efficiently?
thanks



      

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