Convert UTC Datetime With Timezone To Local

I have a string with a date in UTC and tzinfo 'Thu, 01 Oct 2015 00:02:01 +0200' How can I do to convert it to my local time so it outputs '2015-10-02 02:02:01' I tried parser.par

Solution 1:

Here's a stdlib solution:

#!/usr/bin/env python
from datetime import datetime
from email.utils import parsedate_tz, mktime_tz

timestamp = mktime_tz(parsedate_tz("Thu, 01 Oct 2015 00:02:01 +0200"))
print(datetime.fromtimestamp(timestamp)) # get local time

The input time format is rfc 5322 time format that is understood by email module. datetime.fromtimestamp() may fail for past/future dates if it doesn't use a historical time zone database on a given platform. A portable solution is to use pytz module, to get access to the tz database:

#!/usr/bin/env python
from datetime import datetime
from email.utils import parsedate_tz, mktime_tz
import tzlocal # $ pip install tzlocal

local_timezone = tzlocal.get_localzone() # return pytz tzinfo
timestamp = mktime_tz(parsedate_tz("Thu, 01 Oct 2015 00:02:01 +0200"))
print(datetime.fromtimestamp(timestamp, local_timezone))

Solution 2:

I think the following does what you want by implementing a couple of concrete tzinfo classes:

from datetime import datetime, timedelta, tzinfo
import time as _time

_ZERO = timedelta(0)
_STDOFFSET = timedelta(seconds=-_time.timezone)
if _time.daylight:
    _DSTOFFSET = timedelta(seconds=-_time.altzone)
else:
    _DSTOFFSET = _STDOFFSET

_DSTDIFF = _DSTOFFSET - _STDOFFSET

class UTC(tzinfo):
    """ Concrete tzinfo time zone class for UTC
    """
    def utcoffset(self, dt):
        return _ZERO
    def tzname(self, dt):
        return "UTC"
    def dst(self, dt):
        return _ZERO

UTC = UTC()

class LocalTimezone(tzinfo):
    """ Concrete tzinfo time zone class for current timezone
    """
    def utcoffset(self, dt):
        if self._isdst(dt):
            return _DSTOFFSET
        else:
            return _STDOFFSET

    def dst(self, dt):
        if self._isdst(dt):
            return _DSTDIFF
        else:
            return _ZERO

    def tzname(self, dt):
        return _time.tzname[self._isdst(dt)]

    # everything depends on this private method which assumes 'dt' argument
    # is in local time
    def _isdst(self, dt):
        tt = (dt.year, dt.month, dt.day,
              dt.hour, dt.minute, dt.second,
              dt.weekday(), 0, -1)  # last -1 means dst unknown (mktime will fill in)
        stamp = _time.mktime(tt)  # mktime returns secs
        tt = _time.localtime(stamp)  # localtime returns time_struct with tm_isdst attribute
        return tt.tm_isdst > 0

LOCAL = LocalTimezone()

stamp = 'Thu, 01 Oct 2015 00:02:01 +0200'
dt = datetime(*_time.strptime(' '.join(stamp.split()[:-1]),
                              '%a, %d %b %Y %H:%M:%S')[:6], tzinfo=UTC)
local_dt = dt.astimezone(LOCAL)
print(local_dt.strftime('%Y-%M-%d %H:%M:%S'))