How can I get a human-readable timezone name in Python?

Question

In a Python project I'm working on, I'd like to be able to get a "human-readable" timezone name of the form America/New_York, corresponding to the system local timezone, to display to the user. Every piece of code I've seen that accesses timezone information only returns either a numeric offset (-0400) or a letter code (EDT) or sometimes both. Is there some Python library that can access this information, or if not that, convert the offset/letter code into a human-readable name?

If there's more than one human-readable name corresponding to a particular timezone, either a list of the possible results or any one of them is fine, and if there is no human-readable name corresponding to the current time zone, I'll take either an exception or None or [] or whatever.

Answer 1

http://pytz.sourceforge.net/ may be of help. If nothing else, you may be able to grab a list of all of the timezones and then iterate through until you find one that matches your offset.

Answer 2

Check out python-dateutil

py> from dateutil.tz import *
py> ny = gettz('America/New York')
py> ny._filename
'/usr/share/zoneinfo/America/New_York'
py> ny._filename.split('/', 4)[-1]
'America/New_York'

Answer 3

The following generates a defaultdict mapping timezone offsets (e.g. '-0400') and abbreviations (e.g. 'EDT') to common geographic timezone names (e.g. 'America/New_York').

import os
import dateutil.tz as dtz
import pytz
import datetime as dt
import collections

result=collections.defaultdict(list)
for name in pytz.common_timezones:
    timezone=dtz.gettz(name)
    now=dt.datetime.now(timezone)
    offset=now.strftime('%z')
    abbrev=now.strftime('%Z')
    result[offset].append(name)
    result[abbrev].append(name)    
print(result)

Note that timezone abbreviations can have vastly different meanings. For example, 'EST' could stand for Eastern Summer Time (UTC+10) in Australia, or Eastern Standard Time (UTC-5) in North America.

Also, the offsets and abbreviations may change for regions that use daylight standard time. So saving the static dict may not provide the correct timezone name 365 days a year.