hi all, i'm interested in estimating the centre of population of a city and how it might have changed in 10 years. i have a vector polygon layer for each year, which is the ward population. each layer has 198 polygons(wards) with population attributes for each polygon(ward). The distribution of population within a ward is not known, hence assumed uniform for now.
is there a module in GRASS for calculating this. i know we can calculate geographic centroids, but was'nt sure if there was one for this kind of thing. Otherwise i could do it manually by extracting the geographic centroid of each polygon, then the coordinates of the population centre would be: xhat = sum(Pi Xi) /(sum(Pi) yhat = sum(Pi Yi) / sum(Pi) where Xi, Yi are each polygon i's geographic centroids; and Pi are each polygon's population coordinates are in UTM. what do you think? Thanks, Vishal -- Vishal K. Mehta, PhD Scientist Stockholm Environment Institute - US 133 D St Suite F Davis CA 95616 www.sei-us.org
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