Re: st: rescale coordinates using shp2dta, and point order using spmap

[Maurizio Pisati <maurizio.pisati@unimib.it>]

Dear Pablo,



> I am working on producing poverty maps for several countries using the
> commands -shp2dta- and -spmap- and I have few questions about it.
> 
> 1.      We understand that -spmap- is quite compatible with the
> dataset exported by -shp2dta-, but the original coordinates are
> already rescaled in order to have useful values for Stata. However,
> could you tell me how to scale back those values in order to have real
> geographical coordinates?

There is no option in -spmap- (or -shp2dta-) to convert a given coordinate system into another. Thus, if you would like -spmap- to represent your map in "real geographical coordinates", your original shapefile should be expressed -- or converted to -- such coordinate system before it's submitted to -shp2dta-.



> 
> 2.      When -spmap- uses the _ID, _X, and _Y variables, how does
> Stata know the right way to connect the coordinates to graph the dots?
> In other words, how does Stata know the point order do connect the
> points?

-spmap- expects the vertices of any given polygon to be clockwise-ordered.


Best wishes,
Maurizio


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