tools/austria_simplified.py

   1 import argparse
   2 from collections import OrderedDict
   3 import fiona
   4 import shapely.geometry
   5 from fiona.crs import CRS
   6 from fiona.transform import transform_geom
   7 from shapely.wkt import dumps
   8
   9 # data from https://www.naturalearthdata.com/downloads/50m-cultural-vectors/
  10 ZIP_FILE = '/home/philipp/daten/GeoData/naturalearth/v5.1/ne_50m_admin_0_countries.zip'
  11 LAYER_NAME = 'ne_50m_admin_0_countries'
  12 COUNTRY_NAME = 'Austria'
  13
  14
  15 def load_austria():
  16     with fiona.open(f'zip://{ZIP_FILE}', layer=LAYER_NAME) as src:
  17         for feature in src:
  18             properties = feature['properties']
  19             if properties['NAME'] == COUNTRY_NAME:
  20                 return feature['geometry'], src.crs
  21
  22
  23 def simplify_inner(country, crs):
  24     metric_crs = CRS.from_epsg(32632)  # Western Austria (UTM32)
  25     country = transform_geom(crs, metric_crs, country)
  26     country = shapely.geometry.shape(country)
  27     country = country.buffer(-5000)
  28     country = country.simplify(tolerance=5000)
  29     country = shapely.geometry.mapping(country)
  30     country = transform_geom(metric_crs, crs, country)
  31     return country
  32
  33
  34 def save_country(country, crs, name, shapefile):
  35     schema = {
  36         'geometry': 'Polygon',
  37         'properties': OrderedDict([('name', 'str')])
  38     }
  39     with fiona.open(shapefile, 'w', crs=crs, schema=schema, driver='Shapefile') as c:
  40         feature = {
  41             'geometry': country,
  42             'properties': OrderedDict([('name', name)]),
  43         }
  44         c.write(feature)
  45
  46
  47 def print_wkt(country):
  48     country = shapely.geometry.shape(country)
  49     print(dumps(country, rounding_precision=3))
  50
  51
  52 def main(shapefile):
  53     country, crs = load_austria()
  54     simplified_country = simplify_inner(country, crs)
  55     if shapefile:
  56         save_country(simplified_country, crs, COUNTRY_NAME, shapefile)
  57     print_wkt(simplified_country)
  58
  59
  60 if __name__ == '__main__':
  61     parser = argparse.ArgumentParser(description='Creates a simplified version of Austria')
  62     parser.add_argument('--shapefile', default='simplified_austria.shp',
  63                         help='Write result to shape file with this name')
  64     args = parser.parse_args()
  65     main(args.shapefile)