Earthquake checker

usgs_daily_earthquake_check.py

#!/usr/bin/env python

# Load the daily USGS atom feed and see if there are any earthquakes within
# a specified distance of a specified location
import feedparser
import argparse
import math
import sys


# compute the great circle distance using the haversine formula
def GreatCircDist(loc1, loc2):
    dlat = loc2[0] - loc1[0]
    dlong = loc2[1] - loc1[1]
    rdlat = math.radians(dlat)
    rdlong = math.radians(dlong)
    ha = math.sin(rdlat/2) * math.sin(rdlat/2) + \
        math.cos(math.radians(loc1[0])) * \
        math.cos(math.radians(loc2[0]))*math.sin(rdlong/2) * \
        math.sin(rdlong/2)
    hc = 2 * math.atan2(math.sqrt(ha), math.sqrt(1-ha))
    return 6378.1*hc

parser = argparse.ArgumentParser(description="Load the daily USGS atom feed \
        and see if there are any earthquakes within a specified distance of \
        a specified location.")
parser.add_argument('-l', type=float, default=False,
                    help='Latitude of interest.')
parser.add_argument('-g', type=float, default=False,
                    help='Longitude of interest.')
parser.add_argument('-d', type=float, default=False,
                    help='Radius of interest (in km).')
args = parser.parse_args()

if not(args.l and args.g and args.d):
    sys.stderr.write("Error. Incorrect arguments. Exiting.\n")
    sys.exit(1)

usgs = feedparser.parse('http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/2.5_day.atom')

number = 0
for entry in usgs['entries']:
    pos = [float(x) for x in entry['georss_point'].split()]
    dist = GreatCircDist([args.l, args.g], pos)
    if args.d > dist:
        number += 1
        sys.stdout.write(
            entry['title'].split(' -')[0] + ' earthquake ' +
            '{0:0.0f}'.format(dist) + ' km away,' +
            entry['title'].split('-')[1] + ' (' +
            str(pos[0]) + ', ' + str(pos[1]) + ') at an elevation of ' +
            '{0:0.1f}'.format(float(entry['georss_elev'])/1000.) +
            'km.\n')

if not(number):
    sys.stdout.write('No earthquakes within ' + str(args.d) + ' km of (' +
                     str(args.l) + ', ' + str(args.g) + ') in the past 24h.\n')
else:
    sys.stdout.write('\n' + str(number) + ' earthquake')
    if number != 1:
        sys.stdout.write('s')
    sys.stdout.write(' within ' +
                     str(args.d) + ' km of (' + str(args.l) + ', ' +
                     str(args.g) + ') in the past 24h.\n')