Quite so.
Nick
[email protected]
Austin Nichols
> Well, centroid of a polygon on a plane, anyway. A polygon on a
> Mercator projection would not be quite so easy to calculate a centroid
> for if you wanted the centroid of the spherical analog (google
> vincenty or haversine for more details). But I guess if all you want
> it for is for specifying a label location, you don't care about a
> little inaccuracy that varies with latitude, right?
>
> On 2/2/06, n j cox <[email protected]> wrote:
> > This is one definition of the centroid, not an approximation.
> >
> > For some shapes, the centroid might lie outside the area,
> > as is true of many a banana state. This can also be true
> > economically.
> >
> > Nick
> > [email protected]
>
> > Hoetker, Glenn
> >
> > I encountered this a while ago and can't swear that I'm remembering
> > correctly. However, I believe I found that the
> (approximate, at least)
> > centroid for a region corresponded to the average value of
> the x_coord
> > for that region and the average value of the y_coord for that state.
> >
>
> > Friedrich Huebler
> >
> > > With the -tmap- package from SSC it is possible to create maps in
> > > Stata. The help file and user's guide show how labels
> can be added to
> > > a map, with the example of a map of the United States.
> To add labels
> > > it is necessary to specify the x and y coordinates where
> the labels
> > > should be placed. The example database us-database.dta
> contains the
> > > variables x_coord and y_coord that identify the center
> of each state.
> > > Assume that these variables are not present in a
> database. How could
> > > I identify the center of each region where I want the
> labels to be
> > > placed?
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