get_state_geographies.py

#manipulate complex shapes
from shapely.geometry import Polygon, MultiPolygon

#manipulate json objects
import json

#open up the US States Geojson
with open('us_states.geojson') as f:
    states = json.load(f)

#initialize a dictionary to store the state shape info
statePolygons = {}

#for each state ...
for stateInfo in states['features']:
    #get the state name
    stateName = stateInfo['properties']['NAME']
    
    #the state geography is either a Polygon (some shape) or a MultiPolygon (a collection of polygons)
    stateGeographyType = stateInfo['geometry']['type']
    
    #if it's a Polygon, convert the coordinates to a shapely Polygon object
    if stateGeographyType == 'Polygon':
        stateGeometry = Polygon(stateInfo['geometry']['coordinates'][0])
        
    #if its a MultiPolygon, convert each contained polygon into a shapely Polygon object ...
    #and then store the list of Polygons in a shapely MultiPolygon object
    elif stateGeographyType == 'MultiPolygon':
        polygonsInMultipolygon = [Polygon(p[0]) for p in stateInfo['geometry']['coordinates']]
        stateGeometry = MultiPolygon(polygonsInMultipolygon)
    
    #store the state geography info in the dictionary
    statePolygons[stateName] = stateGeometry