sunriseset.py

#!/usr/bin/env python3
# -*- coding: iso-8859-1 -*-

import datetime
import tzinfo_examples as timezone  # implementation of concrete tzinfo subclass
import math
from sun import Sun

__all__ = ['getsuninfo', 'Place']

class Place(object):
    def __init__(self, name, coords, tz=timezone.Pacific):
        self.name = name        # string
        self.coords = coords    # tuple (E/W long, N/S lat)
        self.tz = tz            # tzinfo constant


def _hoursmins(hours):
    """Convert floating point time in hours to integer hrs, mins"""
    frach, h = math.modf(hours)  # get fractional and whole parts
    m = round(frach * 60, 0)     # convert fractional part to whole minutes
    if m == 60:                  # rounded up to whole hour?
        h, m = h + 1, 0
    return int(h), int(m)

def _ymd(date):
    """Return y,m,d from datetime object as tuple"""
    return date.timetuple()[:3]

def getsuninfo(location, date=None):
    """Return local datetime of sunrise, sunset, and length of day in hrs, mins"""
    querydate = datetime.date.today() if date is None else date
    args = _ymd(querydate) + location.coords
    utcrise, utcset = Sun().sunRiseSet(*args)
    daylength = Sun().dayLength(*args)
    hrs, mins = _hoursmins(daylength)

    risehour, risemin = _hoursmins(utcrise)
    sethour, setmin = _hoursmins(utcset)

    # convert times to timedelta values (ie from midnight utc of the date)
    midnight = datetime.datetime(tzinfo=timezone.utc, *_ymd(querydate))
    deltarise = datetime.timedelta(hours=risehour, minutes=risemin)
    utcdatetimerise = midnight + deltarise
    deltaset = datetime.timedelta(hours=sethour, minutes=setmin)
    utcdatetimeset = midnight + deltaset

    # convert results from UTC to local timezone
    localrise = utcdatetimerise.astimezone(location.tz)
    localset = utcdatetimeset.astimezone(location.tz)

    return localrise, localset, hrs, mins

if __name__ == "__main__":
    import datetime
    import timezone

    def unittest(location, testdate):
        risetime, settime, hrs, mins = getsuninfo(location, testdate)

        print("Location: {}".format(location.name))
        print("Date:".format(testdate.strftime("%a %x")))
        print(risetime.strftime("Sunrise %I:%M %p"),
              settime.strftime("- Sunset %I:%M %p (%Z)"))
        print("daylight: %d:%02d" % (hrs, mins))
        print()

    place = Place("My House", (-121.990278, 47.204444), timezone.Pacific)

    # test dates just before and after 2007 DST change
    print("pre 2007")
    print("=========")
    unittest(place, datetime.date(2006, 4, 1))
    unittest(place, datetime.date(2006, 4, 2))
    unittest(place, datetime.date(2006, 10, 28))
    unittest(place, datetime.date(2006, 10, 29))

    print("2007")
    print("=========")
    unittest(place, datetime.date(2007, 3, 10))
    unittest(place, datetime.date(2007, 3, 11))
    unittest(place, datetime.date(2007, 11, 3))
    unittest(place, datetime.date(2007, 11, 4))

    print("Today")
    print("=========")
    unittest(place, datetime.date.today())