text: import json
  import csv
  
  
  def convert_zip_to_county(map_data_usa, county_dict={}):
      """ Maps zip codes to county codes. """
      # open file containing zip codes to county mapping
      with open('zip_lookup.json', 'r') as zipcodes:
          zipcodes_dict = json.load(zipcodes)
  
      for agg_zip, values in map_data_usa.items():
          try:
              county = zipcodes_dict.get(str(agg_zip))['county_COUNTYNS']
          except TypeError:
              continue
          # ignore if zip code does not exist in dict or if it maps to an empty string
          if not county:
              continue
  
          if county_dict.get(county):
              county_dict[county]["number_reports"] += values["number_reports"]
              county_dict[county]["pot"] += values["pot"]
              county_dict[county]["risk"] += values["risk"]
              county_dict[county]["both"] += values["both"]
          else:
              county_dict[county] = values
              county_dict["county_excluded"] = False # for the moment all of these are
              try:
                  del county_dict["fsa_excluded"]
              except KeyError:
                  continue
  
      return county_dict
  
  
  def load_excluded_postal_codes(fname="excluded_postal_codes.csv"):
      with open(fname) as csvfile:
          reader = csv.reader(csvfile)
          first_row = next(reader)
      return first_row
  