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A comment on Finding the World's Economic Center of Gravity. Parent comment

Re:Finding the World's Economic Center of Gravity by codezero on Tuesday July 15, 2014 @01:49AM (#8034982)
Maybe project the x/y coordinates onto a unit sphere, then find the center of mass in spherical coordinates, then convert those spherical coordinates to the relevant 2d coordinate system you're using, discarding the radius (but keeping it for the information it provides).

See also: https://en.wikipedia.org/wiki/Directional_statistics

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Re:Finding the World's Economic Center of Gravity by jofer on Tuesday July 15, 2014 @12:45PM (#8037493)
That's exactly how it's done, for what it worth (though you use 3D cartesian coordinates instead of spherical coordinates).

Treat each point on the sphere as a 3D unit vector, weight as appropriate, and the center of mass is the sum of all of the vectors.

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