build_postcodes.py

#!/usr/bin/env python3
"""

    Fetch list of postcodes from the Icelandic postal service,
    create and print dict mapping postcode to placename and
    other related information. Also adds placenames in the
    nominative case (nefnifall) since the source data only
    includes placenames in dative (þágufall).

    https://www.postur.is/gogn/Gotuskra/postnumer.txt

"""

import requests
import pprint
import logging
import csv
from io import StringIO

from reynir import NounPhrase

from iceaddr.postcodes import POSTCODES


POSTCODES_REMOTE_URL = "https://www.postur.is/gogn/Gotuskra/postnumer.txt"


def _clean_name(name: str) -> str:
    return name.split(" - ")[0].strip()


def main() -> None:
    pc = dict(POSTCODES)
    pc_keys = pc.keys()
    pp = pprint.PrettyPrinter(indent=4)

    req = requests.get(POSTCODES_REMOTE_URL, allow_redirects=True)
    f = StringIO(req.text)

    changed = False
    reader = csv.DictReader(f, delimiter=";")
    for r in reader:
        # CSV file from postur.is only contains postcode placenames in
        # the dative form (þgf.). Try to lemmatise to nominative (nf.) using Reynir.
        postcode = int(r["Póstnúmer"])
        if postcode not in pc_keys:
            logging.warning(f"Postcode '{postcode}' did not already exist in data.")
            changed = True

        tp = r["Tegund"]
        p_dat = _clean_name(r["Staður"])
        p_nom = NounPhrase(p_dat).nominative
        if not p_nom:
            logging.warning(f"Unable to decline placename '{p_dat}'")
            p_nom = p_dat

        if pc[postcode]["stadur_nf"] != p_nom:
            pc[postcode]["stadur_nf"] = p_nom
            print(f"{pc[postcode]['stadur_nf']} --> {p_nom}")
            changed = True

        if pc[postcode]["stadur_tgf"] != p_dat:
            pc[postcode]["stadur_tgf"] = p_dat
            print(f"{pc[postcode]['stadur_tgf']} --> {p_dat}")
            changed = True

        if pc[postcode]["tegund"] != tp:
            pc[postcode]["tegund"] = tp
            print(f"{pc[postcode]['tegund']} --> {tp}")
            changed = True

    if not changed:
        print("No change since last update")
    else:
        pp.pprint(pc)


if __name__ == "__main__":
    """Command line invocation."""
    main()