How can I convert windows timezones to timezones pytz understands?

Question

In a windows python environment I can get the local timezone like this, but it's not usable with pytz:

>>> import win32timezone
>>> win32timezone.TimeZoneInfo.local()
TimeZoneInfo(u'US Mountain Standard Time', True)
>>> win32timezone.TimeZoneInfo.local().timeZoneName
u'US Mountain Standard Time'
>>> tz = pytz.timezone(win32timezone.TimeZoneInfo.local().timeZoneName)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python27\lib\site-packages\pytz\__init__.py", line 185, in timezone
    raise UnknownTimeZoneError(zone)
pytz.exceptions.UnknownTimeZoneError: 'US Mountain Standard Time'

What's a good way to convert that output to a timezone name pytz.timezone() will understand?

---

Here's the answer using tzlocal (thanks to Matt):

>>> from tzlocal.win32 import get_localzone_name
>>> get_localzone_name()
'America/Phoenix'
>>> tz = pytz.timezone(get_localzone_name())
>>> tz
<DstTzInfo 'America/Phoenix' MST-1 day, 17:00:00 STD>

Answer 1

Anurag Uniyal has posted an alternative way to discover timezone names which are consistent with the tzname and utcoffset reported by the computer.

---

Following up on Matt Johnson's solution, here is how you can load the Unicode Common Locale Data Repository (CLDR) mapping from Windows timezone IDs to Olson timezone names:

import lxml.etree as ET
import collections
import pprint
result = {}
doc = ET.parse('http://unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml')
for zone in doc.xpath('//mapZone'):
    attrib = zone.attrib
    if attrib['territory'] == '001':
        result[attrib['other']] = attrib['type']
pprint.pprint(dict(result))

yields

{'AUS Central Standard Time': 'Australia/Darwin',
 'AUS Eastern Standard Time': 'Australia/Sydney',
 'Afghanistan Standard Time': 'Asia/Kabul',
 'Alaskan Standard Time': 'America/Anchorage',
 'Arab Standard Time': 'Asia/Riyadh',
 'Arabian Standard Time': 'Asia/Dubai',
 'Arabic Standard Time': 'Asia/Baghdad',
 'Argentina Standard Time': 'America/Buenos_Aires',
 'Atlantic Standard Time': 'America/Halifax',
 'Azerbaijan Standard Time': 'Asia/Baku',
 'Azores Standard Time': 'Atlantic/Azores',
 'Bahia Standard Time': 'America/Bahia',
 'Bangladesh Standard Time': 'Asia/Dhaka',
 'Canada Central Standard Time': 'America/Regina',
 'Cape Verde Standard Time': 'Atlantic/Cape_Verde',
 'Caucasus Standard Time': 'Asia/Yerevan',
 'Cen. Australia Standard Time': 'Australia/Adelaide',
 'Central America Standard Time': 'America/Guatemala',
 'Central Asia Standard Time': 'Asia/Almaty',
 'Central Brazilian Standard Time': 'America/Cuiaba',
 'Central Europe Standard Time': 'Europe/Budapest',
 'Central European Standard Time': 'Europe/Warsaw',
 'Central Pacific Standard Time': 'Pacific/Guadalcanal',
 'Central Standard Time': 'America/Chicago',
 'Central Standard Time (Mexico)': 'America/Mexico_City',
 'China Standard Time': 'Asia/Shanghai',
 'Dateline Standard Time': 'Etc/GMT+12',
 'E. Africa Standard Time': 'Africa/Nairobi',
 'E. Australia Standard Time': 'Australia/Brisbane',
 'E. Europe Standard Time': 'Asia/Nicosia',
 'E. South America Standard Time': 'America/Sao_Paulo',
 'Eastern Standard Time': 'America/New_York',
 'Egypt Standard Time': 'Africa/Cairo',
 'Ekaterinburg Standard Time': 'Asia/Yekaterinburg',
 'FLE Standard Time': 'Europe/Kiev',
 'Fiji Standard Time': 'Pacific/Fiji',
 'GMT Standard Time': 'Europe/London',
 'GTB Standard Time': 'Europe/Bucharest',
 'Georgian Standard Time': 'Asia/Tbilisi',
 'Greenland Standard Time': 'America/Godthab',
 'Greenwich Standard Time': 'Atlantic/Reykjavik',
 'Hawaiian Standard Time': 'Pacific/Honolulu',
 'India Standard Time': 'Asia/Calcutta',
 'Iran Standard Time': 'Asia/Tehran',
 'Israel Standard Time': 'Asia/Jerusalem',
 'Jordan Standard Time': 'Asia/Amman',
 'Kaliningrad Standard Time': 'Europe/Kaliningrad',
 'Korea Standard Time': 'Asia/Seoul',
 'Magadan Standard Time': 'Asia/Magadan',
 'Mauritius Standard Time': 'Indian/Mauritius',
 'Middle East Standard Time': 'Asia/Beirut',
 'Montevideo Standard Time': 'America/Montevideo',
 'Morocco Standard Time': 'Africa/Casablanca',
 'Mountain Standard Time': 'America/Denver',
 'Mountain Standard Time (Mexico)': 'America/Chihuahua',
 'Myanmar Standard Time': 'Asia/Rangoon',
 'N. Central Asia Standard Time': 'Asia/Novosibirsk',
 'Namibia Standard Time': 'Africa/Windhoek',
 'Nepal Standard Time': 'Asia/Katmandu',
 'New Zealand Standard Time': 'Pacific/Auckland',
 'Newfoundland Standard Time': 'America/St_Johns',
 'North Asia East Standard Time': 'Asia/Irkutsk',
 'North Asia Standard Time': 'Asia/Krasnoyarsk',
 'Pacific SA Standard Time': 'America/Santiago',
 'Pacific Standard Time': 'America/Los_Angeles',
 'Pacific Standard Time (Mexico)': 'America/Santa_Isabel',
 'Pakistan Standard Time': 'Asia/Karachi',
 'Paraguay Standard Time': 'America/Asuncion',
 'Romance Standard Time': 'Europe/Paris',
 'Russian Standard Time': 'Europe/Moscow',
 'SA Eastern Standard Time': 'America/Cayenne',
 'SA Pacific Standard Time': 'America/Bogota',
 'SA Western Standard Time': 'America/La_Paz',
 'SE Asia Standard Time': 'Asia/Bangkok',
 'Samoa Standard Time': 'Pacific/Apia',
 'Singapore Standard Time': 'Asia/Singapore',
 'South Africa Standard Time': 'Africa/Johannesburg',
 'Sri Lanka Standard Time': 'Asia/Colombo',
 'Syria Standard Time': 'Asia/Damascus',
 'Taipei Standard Time': 'Asia/Taipei',
 'Tasmania Standard Time': 'Australia/Hobart',
 'Tokyo Standard Time': 'Asia/Tokyo',
 'Tonga Standard Time': 'Pacific/Tongatapu',
 'Turkey Standard Time': 'Europe/Istanbul',
 'US Eastern Standard Time': 'America/Indianapolis',
 'US Mountain Standard Time': 'America/Phoenix',
 'UTC': 'Etc/GMT',
 'UTC+12': 'Etc/GMT-12',
 'UTC-02': 'Etc/GMT+2',
 'UTC-11': 'Etc/GMT+11',
 'Ulaanbaatar Standard Time': 'Asia/Ulaanbaatar',
 'Venezuela Standard Time': 'America/Caracas',
 'Vladivostok Standard Time': 'Asia/Vladivostok',
 'W. Australia Standard Time': 'Australia/Perth',
 'W. Central Africa Standard Time': 'Africa/Lagos',
 'W. Europe Standard Time': 'Europe/Berlin',
 'West Asia Standard Time': 'Asia/Tashkent',
 'West Pacific Standard Time': 'Pacific/Port_Moresby',
 'Yakutsk Standard Time': 'Asia/Yakutsk'}

If you do not wish your program to depend on lxml or a network connection, you could stick this dict in a module and use it from there.