using geokit or other ruby gem to calculate the center of a series of geo coordinates

开发者_开发技巧I've been using the geokit and geokit-rails gem for rails for awhile but one question I haven't found answered is how to find the calculated aggregate center for a collection of points. I know how to calculate the distance between two points, but not more than 2.

My reason is, I have a series of points all in the same city... all things being perfect the city would have a center which I could just use, but some cities, say berlin do not have a perfect center. They have multiple centers, and I just want to use the whole list of places I have in my database to calculate a center for a particular distribution. Has anyone else had this problem?

Any tips? Thanks

Having never used Geokit before, the math behind this operation is relatively simple to implement yourself. Assuming these points consist of a latitude and a longitude, you just need the average latitude and average longitude for all the points. Once you have those two values, you've got your center point.

points = [[14, 19], [-5, 57], [23, -12]]
points.transpose.map{|c| c.inject{|a, b| a + b}.to_f / c.size}

Likewise, if these points are Geokit::LatLng objects instead of a 2-dimensional array, you can just map their lat and lng values simply by calling #to_a on them beforehand.

points.map(&:to_a).transpose.map{|c| c.inject{|a, b| a + b}.to_f / c.size}