trim_csv.py

#!/usr/bin/env python3
"""Cut unneeded info out of geonames csv, to make parsing faster."""


import csv
import sys
from pathlib import Path

# http://download.geonames.org/export/dump/
# The main 'geoname' table has the following fields :
# ---------------------------------------------------
# geonameid         : integer id of record in geonames database
# name              : name of geographical point (utf8) varchar(200)
# asciiname         : name of geographical point in plain ascii characters, varchar(200)
# alternatenames    : alternatenames, comma separated, ascii names automatically transliterated, convenience attribute from alternatename table, varchar(10000)
# latitude          : latitude in decimal degrees (wgs84)
# longitude         : longitude in decimal degrees (wgs84)
# feature class     : see http://www.geonames.org/export/codes.html, char(1)
# feature code      : see http://www.geonames.org/export/codes.html, varchar(10)
# country code      : ISO-3166 2-letter country code, 2 characters
# cc2               : alternate country codes, comma separated, ISO-3166 2-letter country code, 200 characters
# admin1 code       : fipscode (subject to change to iso code), see exceptions below, see file admin1Codes.txt for display names of this code; varchar(20)
# admin2 code       : code for the second administrative division, a county in the US, see file admin2Codes.txt; varchar(80)
# admin3 code       : code for third level administrative division, varchar(20)
# admin4 code       : code for fourth level administrative division, varchar(20)
# population        : bigint (8 byte int)
# elevation         : in meters, integer
# dem               : digital elevation model, srtm3 or gtopo30, average elevation of 3''x3'' (ca 90mx90m) or 30''x30'' (ca 900mx900m) area in meters, integer. srtm processed by cgiar/ciat.
# timezone          : the iana timezone id (see file timeZone.txt) varchar(40)
# modification date : date of last modification in yyyy-MM-dd format

cities = Path(sys.argv[1])
with cities.open("r") as f:
    reader = csv.reader(f, dialect=csv.excel_tab)
    for line in reader:
        name, lat, long = line[1], float(line[4]), float(line[5])
        country = line[8]
        fipscode = line[10]
        lat = round(lat, 2)
        long = round(long, 2)
        print(f"{name}\t{country}\t{fipscode}\t{lat}\t{long}")