Python时区转换会增加小时数吗？ [英] Python timezone conversion adding minutes to the hour?

问题描述

因此，我试图将一小时（10：00：00、14：00：00等）从给定时区转换为UTC。

So I'm trying to convert a bunch of hours (10:00:00, 14:00:00, etc) from a given timezone to UTC.

这样做的时候，我会一直疯狂地回想起诸如 15:51:00之类的东西。

When I do so, I keep maddeningly getting things back like "15:51:00".

当您到达该行并打印其使用的值时，

When you get to that line, and print what value it's using, it's using something like:

1900-01-01 12:00:00-05:51

除了-05：51位之外，其他都可以。我不知道为什么有-05：51，这给我带来了麻烦。 UTC转换是小时到小时，是吗？我认为这与我的时区转换有关，但我真的不明白为什么他们会这样做。

Which is fine, except for the -05:51 bit. I have no idea why that -05:51 is there, and it's causing me problems. UTC conversion is hour to hour, yes? I think it's got something to do with my timezone conversions, but I really don't get why they would be doing that.

这是一个最小的例子，有同样的错误输出;它会返回 15:51:00 ，而应该只返回一个固定的小时，没有分钟。

Here's a minimal example that has the same erroneous output; it returns 15:51:00 when it should just return a flat hour, no minutes.

import datetime
from dateutil import tz

jj = datetime.datetime.strptime("10:00:00", "%H:%M:%S")

tzz = tz.gettz('US/Central')

def constructstring(tzz,x):
    inter2 = x.replace(tzinfo=tzz) #ERROR HAPPENS HERE (I'm pretty sure anyways)
    inter3 = inter2.astimezone(tz.tzutc())
    return inter3

print(constructstring(tzz,jj).strftime("%H:%M:%S"))

推荐答案

在创建 jj datetime对象时未指定日期，因此使用默认日期1900-01-01。时区不是固定的实体；它们会随时间变化，因此美国/中部时区在1900年使用了不同的偏移量。

You are not specifying a date when you create the jj datetime object, so the default date of 1900-01-01 is used. Timezones are not fixed entities; they change over time, and the US/Central timezone used a different offset back in 1900.

至少，请使用最近的日期，例如 today 例如：

At the very least, use a recent date, like today for example:

# use today's date, with the time from jj, and a given timezone.
datetime.datetime.combine(datetime.date.today(), jj.time(), tzinfo=tzz)

如果只需要一个时间，则不要创建 datetime 对象来存储它们； datetime 模块具有专用的 time（）对象。我也不会使用 strftime（）从文字中创建对象。只需使用构造函数来传递整数：

If all you need is a time, then don't create datetime objects to store those; the datetime module has a dedicated time() object. I'd also not use strftime() to create objects from literals. Just use the constructor to pass in integers:

jj = datetime.time(10, 0, 0)  # or just .time(10)

其他好的经验法则：如果必须处理带时区的日期，请尝试在代码接收或加载它们时，将它们移动到UTC中的 datetime 对象。如果您只有一天中的某个时间，但仍需要时区支持，请将它们附加到今天的日期，这样您就可以获得正确的时区。仅在尽可能晚的时候再次转换为字符串。

Other good rules of thumb: If you have to deal with dates with timezones, try to move those to datetime objects in UTC the moment your code receives or loads them. If you only have a time of day, but still need timezone support, attach them to today's date, so you get the right timezone. Only convert to strings again as late as possible.

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