Some sample code showing how to use the python timezone library - pytz

pytz_tests.py

#!/usr/bin/python3

'''
Tests to learn how to use the pytz timezone library properly
http://pytz.sourceforge.net
'''

import os
import sys
import datetime

import pytz


# Krystof utils
KRYSTOF_UTILS_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)),
                                  'krystof-utils', 'python')
sys.path.append(KRYSTOF_UTILS_PATH)
from krystof_utils import MSG, TODO


TIME_FORMAT = '%Y-%m-%d %H:%M:%S %Z%z'


def get_tz_offset_from_utc_str(tz_name, dt):
  '''
  get the offset between the timezone named tz_name and UTC on at datetime dt
  dt is a datetime.datetime
  returns a string like "-06"
  '''
  # uses noon to be avoid any weirdness around the start and end of DST
  tz        = pytz.timezone(tz_name)
  localtime = tz.localize(dt)
  offset    = localtime.strftime('%z')
  
  MSG("localtime: {}".format(localtime.strftime(TIME_FORMAT)))
  MSG("offset   : {}".format(offset))
  
  return offset
  


if __name__ == '__main__':

  MSG("pytz version: {}".format(pytz.__version__))

  MSG("US time zones: {}".format(', '.join(pytz.country_timezones('US'))))

  # CA timezone
  catz = pytz.timezone('America/Los_Angeles')

  # A date when daylight saving time is NOT in effect
  LA_winter = catz.localize(datetime.datetime(2019, 1, 8, 0, 0))
  MSG("LA time (WINTER): {}".format(LA_winter.strftime(TIME_FORMAT)))

  # A date when DST IS in effect
  LA_summer = catz.localize(datetime.datetime(2019, 8, 8, 0, 0))
  MSG("LA time (summer): {}".format(LA_summer.strftime(TIME_FORMAT)))
  
  offset = get_tz_offset_from_utc_str('America/Los_Angeles',
                                      datetime.datetime(2019, 8, 8, 0, 0))
  MSG('summer offset: {}'.format(offset))