Create a point grid style cartogram from polygon-based geographic data.
Takes an evenly-spaced grid of point at 20 mile intervals, estimates the population for that point by taking a weighted average of the population of counties within 20 miles of that point. The estimated population at a given point is encoded by the circle’s area.
The geoprocessing methods used here for taking point buffers and calculating the polygon intersections are slow compared to using something like PostGIS or shapely.