如何在Python中查找同一小时（包括DST）的第二天的Unix时间戳？ [英] How to find next day's Unix timestamp for same hour, including DST, in Python?

问题描述

在Python中，我可以像这样（使用pytz）知道时区，找到本地时间的Unix时间戳：

In Python, I can find the Unix time stamp of a local time, knowing the time zone, like this (using pytz):

>>> import datetime as DT
>>> import pytz
>>> mtl = pytz.timezone('America/Montreal')
>>> naive_time3 = DT.datetime.strptime('2013/11/03', '%Y/%m/%d')
>>> naive_time3
datetime.datetime(2013, 11, 3, 0, 0)
>>> localized_time3 = mtl.localize(naive_time3)
>>> localized_time3
datetime.datetime(2013, 11, 3, 0, 0, tzinfo=<DstTzInfo 'America/Montreal' EDT-1 day, 20:00:00 DST>)
>>> localized_time3.timestamp()
1383451200.0

到目前为止，很好。 naive_time 未知时区，而 localized_time 知道2013年11月3日午夜蒙特利尔，因此（UTC）Unix时间戳很好。此时区也是我的本地时区，并且此时间戳似乎正确：

So far, so good. naive_time is not aware of the time zone, whereas localized_time knows its midnight on 2013/11/03 in Montréal, so the (UTC) Unix time stamp is good. This time zone is also my local time zone and this time stamp seems right:

$ date -d @1383451200
Sun Nov  3 00:00:00 EDT 2013

现在，时钟在11月3日向后调整了一个小时2:00在蒙特利尔，所以那天我们多了一个小时。这表示在2013/11/03至2013/11/04之间有 25小时。这表明：

Now, clocks were adjusted one hour backward November 3rd at 2:00 here in Montréal, so we gained an extra hour that day. This means that there were, here, 25 hours between 2013/11/03 and 2013/11/04. This shows it:

>>> naive_time4 = DT.datetime.strptime('2013/11/04', '%Y/%m/%d')
>>> localized_time4 = mtl.localize(naive_time4)
>>> localized_time4
datetime.datetime(2013, 11, 4, 0, 0, tzinfo=<DstTzInfo 'America/Montreal' EST-1 day, 19:00:00 STD>)
>>> (localized_time4.timestamp() - localized_time3.timestamp()) / 3600
25.0

现在，我正在寻找一种简单的方法来从 localized_time3 获取 localized_time4 对象，因为我想获取下一个同一小时（此处为午夜）的本地化日期。我尝试了 timedelta ，但我认为它不知道时区或DST：

Now, I'm looking for an easy way to get the localized_time4 object from localized_time3, knowing I want to get the next localized day at the same hour (here, midnight). I tried timedelta, but I believe it's not aware of time zones or DST:

>>> localized_time4td = localized_time3 + DT.timedelta(1)
>>> localized_time4td
datetime.datetime(2013, 11, 4, 0, 0, tzinfo=<DstTzInfo 'America/Montreal' EDT-1 day, 20:00:00 DST>)
>>> (localized_time4td.timestamp() - localized_time3.timestamp()) / 3600
24.0

我的目的是获取有关每个本地日以Unix时间戳存储的日志条目的信息。当然，如果我使用 localized_time3.timestamp（）并在此处添加 24 * 3600 （这与 localized_time4td.timestamp（）），我会错过在 localized_time4td.timestamp（）和<$之间发生的所有日志条目c $ c> localized_time4td.timestamp（）+ 3600 。

My purpose is to get informations about log entries that are stored with their Unix timestamp for each local day. Of course, if I use localized_time3.timestamp() and add 24 * 3600 here (which will be the same as localized_time4td.timestamp()), I will miss all log entries that happened between localized_time4td.timestamp() and localized_time4td.timestamp() + 3600.

换句话说，我正在寻找的函数或方法应该知道何时

In other words, the function or method I'm looking for should know when to add 25 hours, 24 hours or 23 hours sometimes to a Unix time stamp, depending on when DST shifts happen.

推荐答案

无，根据Unix时间戳的变化，有时会在Unix时间戳上添加25小时，24小时或23小时。使用新软件包：

Without using a new package:

def add_day(x):
    d = x.date()+DT.timedelta(1)
    return mtl.localize(x.replace(year=d.year, month=d.month, day=d.day, tzinfo=None))

完整脚本：

import datetime as DT
import pytz
import calendar
mtl = pytz.timezone('America/Montreal')
naive_time3 = DT.datetime.strptime('2013/11/03', '%Y/%m/%d')
print repr(naive_time3)
#datetime.datetime(2013, 11, 3, 0, 0)
localized_time3 = mtl.localize(naive_time3)
print repr(localized_time3)
#datetime.datetime(2013, 11, 3, 0, 0, tzinfo=<DstTzInfo 'America/Montreal' EDT-1 day, 20:00:00 DST>)
print calendar.timegm(localized_time3.utctimetuple())
#1383451200.0
def add_day(x):
    d = x.date()+DT.timedelta(1)
    return mtl.localize(x.replace(year=d.year, month=d.month, day=d.day, tzinfo=None))
print repr(add_day(localized_time3))
#datetime.datetime(2013, 11, 4, 0, 0, tzinfo=<DstTzInfo 'America/Montreal' EST-1 day, 19:00:00 STD>)

（日历适用于Python2。）

(calendar is for Python2.)

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