extending ne_10m_admin_0_countries.shp

addcolumns.py

from shapely.geometry import mapping, shape
import fiona

with fiona.open('./10m_cultural/ne_10m_admin_0_countries.shp', 'r', encoding='utf-8' ) as input:
    schema = input.schema.copy()
    input_crs = input.crs

    # add area_sqkm property if not present in the schema add it
    if not hasattr( schema['properties'], 'area_sqkm'):
        schema['properties']['area_sqkm'] = 'float:22.2'

    #add population
    if not hasattr( schema['properties'], 'population'):
        schema['properties']['population'] = 'int:12'

    with fiona.open('./10m_cultural/ne2_10m_admin_0_countries.shp', 'w', 'ESRI Shapefile', schema, input_crs, encoding='utf-8' ) as output:
         for elem in input:
              elem['properties']['area_sqkm']= 0.0
              elem['properties']['population']= 0
              output.write({'properties':elem['properties'],'geometry': mapping(shape(elem['geometry']))})