Did anyone have thoughts on this? :-) Aren
On Wed, May 4, 2011 at 2:12 PM, Aren Cambre <a...@arencambre.com> wrote: > The more I think about it, is this a job for R? I know I need to start > using R at some point, just haven't begun yet. > > Aren > > > On Wed, May 4, 2011 at 1:42 PM, Aren Cambre <a...@arencambre.com> wrote: > >> Suppose you have a geometry type with a multipoint. How would you >> calculate the variance of the points in that multipoint? >> >> I looked through the PostGIS 1.5 function reference and am not coming up >> with any easy way. >> >> A hard way seems to be using st_centroid(multipoint) to find the >> multipoint's center. From there, I can calculate the distance of each point >> from its center, and use that towards calculating the variance (each >> distance is squared, all squared distances are added together, then divide >> by number of points). >> >> I guess my ultimate need is to measure relative dispersion of multipoints. >> The multipoints that have the most dispersion are suspect, but I need a way >> of identifying which ones are like this. >> >> Aren >> > >
_______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
