如何获得一天的第一个日期时间? [英] How to get the first datetime of a day?
问题描述
使用pytz和Python 3.4,如何获得给定时区的第一个 datetime
(让我们说,2014-10-19) 'America / Sao_Paulo'
)?
Using pytz and Python 3.4, how to get the first datetime
of a given day (lets say, 2014-10-19), in a given timezone (lets say 'America/Sao_Paulo'
)?
推荐答案
使用 localize()
方法附加时区:
from datetime import datetime
import pytz # $ pip install pytz
tz = pytz.timezone('America/Sao_Paulo')
naive = datetime(2014, 10, 19)
aware = tz.localize(naive, is_dst=None)
如果运行代码;它生成 NonExistentTimeError
。如何处理此错误取决于应用程序,例如,在午夜附近获得一些有效的本地时间:
If you run the code; it generates NonExistentTimeError
. How to deal with this error depends on the application e.g., to get some valid local time near the midnight:
aware = tz.normalize(tz.localize(naive, is_dst=False))
或者你可以增加时间分钟分钟,直到您得到一个有效的本地(圣保罗)时间:
Or you could increment the time minute by minute until you'll get a valid local (Sao Paulo) time:
from datetime import datetime, timedelta
import pytz # $ pip install pytz
tz = pytz.timezone('America/Sao_Paulo')
d = naive = datetime(2014, 10, 19)
while True:
try:
aware = tz.localize(d, is_dst=None)
except pytz.AmbiguousTimeError:
aware = tz.localize(d, is_dst=False)
assert tz.localize(d, is_dst=False) > tz.localize(d, is_dst=True)
break
except pytz.NonExistentTimeError:
d += timedelta(minutes=1) # try future time
continue
else:
break
结果:
>>> aware
datetime.datetime(2014, 10, 19, 1, 0, tzinfo=<DstTzInfo 'America/Sao_Paulo' BRST-1 day, 22:00:00 DST>
>>> aware.strftime('%Y-%m-%d %H:%M:%S %Z%z')
'2014-10-19 01:00:00 BRST-0200'
注意:第一个有效时间是 01:00
on那天,时区是UTC后两个小时(local = utc - 2)。
Note: the first valid time is 01:00
on that day. And the timezone is two hours behind UTC (local = utc - 2).
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