KML get centroid

kml_get_centroid.py

#!/usr/bin/env python
# hobbes3

import xml.etree.ElementTree as ET
import csv
from statistics import mean

KML_FILE = "sf_blocks.kml"
CSV_FILE = "sf_blocks_lat_lon.csv"
CSV_COLUMNS = ["BLKLOT", "lat", "lon"]

tree = ET.parse(KML_FILE)

centroids = []

for placemark in tree.iter("Placemark"):
    blklot = placemark.find(".//Data[@name='blklot']/value").text
    coords = placemark.find(".//coordinates").text.strip().split("\n")

    lats = []
    lons = []

    print("BLKLOT: {}".format(blklot))

    for coord in coords:
        lats.append(float(coord.split(",")[1]))
        lons.append(float(coord.split(",")[0]))

#    import pdb; pdb.set_trace()

    c_lat = mean(lats)
    c_lon = mean(lons)

    print("Centroid: {}, {}".format(blklot, c_lat, c_lon))

    centroids.append({
        "BLKLOT": blklot,
        "lat": c_lat,
        "lon": c_lon,
    })

try:
    with open(CSV_FILE, 'w') as csvfile:
        writer = csv.DictWriter(csvfile, fieldnames=CSV_COLUMNS)
        writer.writeheader()

        for centroid in centroids:
            writer.writerow(centroid)

except IOError:
    print("I/O error")