modules/getCountrycode.py

import geopandas as gpd

# Sample DataFrame acording to actual structure (use your own data)
data = {'GID_1': ['DEU.1_1','DEU.2_1'],
        'GID_0': ['DEU', 'DEU'],
        'COUNTRY': ['Germany', 'Germany'],
        'NAME_1': ['Baden-Würtenberg', 'Bayern'],
        'VARNAME_1': ['NA','Bavaria'],
        'NL_NAME_1': ['NA', 'NA'],
        'TYPE_1': ['Land', 'Freistaat'],
        'ENGTYPE_1': ['State', 'Freestate'],
        'CC_1': ['08','09'],
        'HASC_1': ['DE.BW', 'DE.BY'], # Extra for subnational countys (https://de.wikipedia.org/wiki/Hierarchical_administrative_subdivision_codes)
        'ISO_1': ['NA', 'DE-BY'], # International Order --> Check First (https://de.wikipedia.org/wiki/ISO_3166)
        'geometry': [0,1]
}
gdf = gpd.GeoDataFrame(data)

# function to generate output
# Land should be a line from the geojson-table
# Currently only works for NUTS-1 areas!!!

def getCountrycode(land):
    if land['ISO_1'] != 'NA':
        return land['ISO_1']
    elif land['HASC_1']:
        return land['HASC_1']
    else:
        return False