def localize(self, dt, is_dst=False):
'''Convert naive time to local time.
This method should be used to construct localtimes, rather
than passing a tzinfo argument to a datetime constructor.
is_dst is used to determine the correct timezone in the ambigous
period at the end of daylight saving time.
>>> from pytz import timezone
>>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
>>> amdam = timezone('Europe/Amsterdam')
>>> dt = datetime(2004, 10, 31, 2, 0, 0)
>>> loc_dt1 = amdam.localize(dt, is_dst=True)
>>> loc_dt2 = amdam.localize(dt, is_dst=False)
>>> loc_dt1.strftime(fmt)
'2004-10-31 02:00:00 CEST (+0200)'
>>> loc_dt2.strftime(fmt)
'2004-10-31 02:00:00 CET (+0100)'
>>> str(loc_dt2 - loc_dt1)
'1:00:00'
Use is_dst=None to raise an AmbiguousTimeError for ambiguous
times at the end of daylight saving time
>>> try:
... loc_dt1 = amdam.localize(dt, is_dst=None)
... except AmbiguousTimeError:
... print('Ambiguous')
Ambiguous
is_dst defaults to False
>>> amdam.localize(dt) == amdam.localize(dt, False)
True
is_dst is also used to determine the correct timezone in the
wallclock times jumped over at the start of daylight saving time.
>>> pacific = timezone('US/Pacific')
>>> dt = datetime(2008, 3, 9, 2, 0, 0)
>>> ploc_dt1 = pacific.localize(dt, is_dst=True)
>>> ploc_dt2 = pacific.localize(dt, is_dst=False)
>>> ploc_dt1.strftime(fmt)
'2008-03-09 02:00:00 PDT (-0700)'
>>> ploc_dt2.strftime(fmt)
'2008-03-09 02:00:00 PST (-0800)'
>>> str(ploc_dt2 - ploc_dt1)
'1:00:00'
Use is_dst=None to raise a NonExistentTimeError for these skipped
times.
>>> try:
... loc_dt1 = pacific.localize(dt, is_dst=None)
... except NonExistentTimeError:
... print('Non-existent')
Non-existent
'''
if dt.tzinfo is not None:
raise ValueError('Not naive datetime (tzinfo is already set)')
# Find the two best possibilities.
possible_loc_dt = set()
for delta in [timedelta(days=-1), timedelta(days=1)]:
loc_dt = dt + delta
idx = max(0, bisect_right(
self._utc_transition_times, loc_dt) - 1)
inf = self._transition_info[idx]
tzinfo = self._tzinfos[inf]
loc_dt = tzinfo.normalize(dt.replace(tzinfo=tzinfo))
if loc_dt.replace(tzinfo=None) == dt:
possible_loc_dt.add(loc_dt)
if len(possible_loc_dt) == 1:
return possible_loc_dt.pop()
# If there are no possibly correct timezones, we are attempting
# to convert a time that never happened - the time period jumped
# during the start-of-DST transition period.
if len(possible_loc_dt) == 0:
# If we refuse to guess, raise an exception.
if is_dst is None:
raise NonExistentTimeError(dt)
# If we are forcing the pre-DST side of the DST transition, we
# obtain the correct timezone by winding the clock forward a few
# hours.
elif is_dst:
return self.localize(
dt + timedelta(hours=6), is_dst=True) - timedelta(hours=6)
# If we are forcing the post-DST side of the DST transition, we
# obtain the correct timezone by winding the clock back.
else:
return self.localize(
dt - timedelta(hours=6),
is_dst=False) + timedelta(hours=6)
# If we get this far, we have multiple possible timezones - this
# is an ambiguous case occuring during the end-of-DST transition.
# If told to be strict, raise an exception since we have an
# ambiguous case
if is_dst is None:
raise AmbiguousTimeError(dt)
# Filter out the possiblilities that don't match the requested
# is_dst
filtered_possible_loc_dt = [
p for p in possible_loc_dt if bool(p.tzinfo._dst) == is_dst
]
# Hopefully we only have one possibility left. Return it.
if len(filtered_possible_loc_dt) == 1:
return filtered_possible_loc_dt[0]
if len(filtered_possible_loc_dt) == 0:
filtered_possible_loc_dt = list(possible_loc_dt)
# If we get this far, we have in a wierd timezone transition
# where the clocks have been wound back but is_dst is the same
# in both (eg. Europe/Warsaw 1915 when they switched to CET).
# At this point, we just have to guess unless we allow more
# hints to be passed in (such as the UTC offset or abbreviation),
# but that is just getting silly.
#
# Choose the earliest (by UTC) applicable timezone if is_dst=True
# Choose the latest (by UTC) applicable timezone if is_dst=False
# i.e., behave like end-of-DST transition
dates = {} # utc -> local
for local_dt in filtered_possible_loc_dt:
utc_time = (
local_dt.replace(tzinfo=None) - local_dt.tzinfo._utcoffset)
assert utc_time not in dates
dates[utc_time] = local_dt
return dates[[min, max][not is_dst](dates)]
def localize(self, dt, is_dst = False):
"""Convert naive time to local time.
This method should be used to construct localtimes, rather
than passing a tzinfo argument to a datetime constructor.
is_dst is used to determine the correct timezone in the ambigous
period at the end of daylight saving time.
>>> from pytz import timezone
>>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
>>> amdam = timezone('Europe/Amsterdam')
>>> dt = datetime(2004, 10, 31, 2, 0, 0)
>>> loc_dt1 = amdam.localize(dt, is_dst=True)
>>> loc_dt2 = amdam.localize(dt, is_dst=False)
>>> loc_dt1.strftime(fmt)
'2004-10-31 02:00:00 CEST (+0200)'
>>> loc_dt2.strftime(fmt)
'2004-10-31 02:00:00 CET (+0100)'
>>> str(loc_dt2 - loc_dt1)
'1:00:00'
Use is_dst=None to raise an AmbiguousTimeError for ambiguous
times at the end of daylight saving time
>>> try:
... loc_dt1 = amdam.localize(dt, is_dst=None)
... except AmbiguousTimeError:
... print('Ambiguous')
Ambiguous
is_dst defaults to False
>>> amdam.localize(dt) == amdam.localize(dt, False)
True
is_dst is also used to determine the correct timezone in the
wallclock times jumped over at the start of daylight saving time.
>>> pacific = timezone('US/Pacific')
>>> dt = datetime(2008, 3, 9, 2, 0, 0)
>>> ploc_dt1 = pacific.localize(dt, is_dst=True)
>>> ploc_dt2 = pacific.localize(dt, is_dst=False)
>>> ploc_dt1.strftime(fmt)
'2008-03-09 02:00:00 PDT (-0700)'
>>> ploc_dt2.strftime(fmt)
'2008-03-09 02:00:00 PST (-0800)'
>>> str(ploc_dt2 - ploc_dt1)
'1:00:00'
Use is_dst=None to raise a NonExistentTimeError for these skipped
times.
>>> try:
... loc_dt1 = pacific.localize(dt, is_dst=None)
... except NonExistentTimeError:
... print('Non-existent')
Non-existent
"""
if dt.tzinfo is not None:
raise ValueError('Not naive datetime (tzinfo is already set)')
possible_loc_dt = set()
for delta in [timedelta(days=-1), timedelta(days=1)]:
loc_dt = dt + delta
idx = max(0, bisect_right(self._utc_transition_times, loc_dt) - 1)
inf = self._transition_info[idx]
tzinfo = self._tzinfos[inf]
loc_dt = tzinfo.normalize(dt.replace(tzinfo=tzinfo))
if loc_dt.replace(tzinfo=None) == dt:
possible_loc_dt.add(loc_dt)
if len(possible_loc_dt) == 1:
return possible_loc_dt.pop()
if len(possible_loc_dt) == 0:
if is_dst is None:
raise NonExistentTimeError(dt)
elif is_dst:
return self.localize(dt + timedelta(hours=6), is_dst=True) - timedelta(hours=6)
else:
return self.localize(dt - timedelta(hours=6), is_dst=False) + timedelta(hours=6)
if is_dst is None:
raise AmbiguousTimeError(dt)
filtered_possible_loc_dt = [ p for p in possible_loc_dt if bool(p.tzinfo._dst) == is_dst ]
if len(filtered_possible_loc_dt) == 1:
return filtered_possible_loc_dt[0]
if len(filtered_possible_loc_dt) == 0:
filtered_possible_loc_dt = list(possible_loc_dt)
sorting_keys = {}
for local_dt in filtered_possible_loc_dt:
key = local_dt.replace(tzinfo=None) - local_dt.tzinfo._utcoffset
sorting_keys[key] = local_dt
first_key = sorted(sorting_keys)[0]
return sorting_keys[first_key]
