如何在 python 中计算两个时区之间的时差


如何在

Python 中计算两个时区之间的时差?也就是说,我不想比较 TZ 感知datetime对象并获得timedelta;我想比较两个TimeZone对象并得到一个offset_hours.datetime库中没有任何内容可以处理此问题,pytz也没有。

这是一个使用 Python 库 Pytz 的解决方案,它解决了夏令时结束时时间不明确的问题。


from pytz import timezone
import pandas as pd
def tz_diff(date, tz1, tz2):
    '''
    Returns the difference in hours between timezone1 and timezone2
    for a given date.
    '''
    date = pd.to_datetime(date)
    return (tz1.localize(date) - 
            tz2.localize(date).astimezone(tz1))
            .seconds/3600

以下示例分别计算 UTC 和澳大利亚时间在 1 月 1 日和 6 月 1 日之间的小时差。请注意如何考虑夏令时。

utc = timezone('UTC')
aus = timezone('Australia/Sydney')
tz_diff('2017-01-01', utc, aus)
# 11.0
tz_diff('2017-06-01', utc, aus)
# 10.0

谢谢

您必须知道的第一件事是,两个时区之间的偏移量不仅取决于所讨论的时区,还取决于您询问的日期。例如,夏令时的开始和结束日期在美国的日期在 2007 年发生了变化。虽然基本时区物流在任何单一地点变化很少,但全球的变化速度是不容忽视的。因此,您必须将有问题的日期合并到您的函数中。

完成必要的序言后,如果您利用钟摆库,实际功能并不难编写。它应该看起来像这样:

import pendulum
def tz_diff(home, away, on=None):
    """
    Return the difference in hours between the away time zone and home.
    `home` and `away` may be any values which pendulum parses as timezones.
    However, recommended use is to specify the full formal name.
    See https://gist.github.com/pamelafox/986163
    As not all time zones are separated by an integer number of hours, this
    function returns a float.
    As time zones are political entities, their definitions can change over time.
    This is complicated by the fact that daylight savings time does not start
    and end on the same days uniformly across the globe. This means that there are
    certain days of the year when the returned value between `Europe/Berlin` and
    `America/New_York` is _not_ `6.0`.
    By default, this function always assumes that you want the current
    definition. If you prefer to specify, set `on` to the date of your choice.
    It should be a `Pendulum` object.
    This function returns the number of hours which must be added to the home time
    in order to get the away time. For example,
    ```python
    >>> tz_diff('Europe/Berlin', 'America/New_York')
    -6.0
    >>> tz_diff('Europe/Berlin', 'Asia/Kabul')
    2.5
    ```
    """
    if on is None:
        on = pendulum.today()
    diff = (on.set(tz=home) - on.set(tz=away)).total_hours()
    # what about the diff from Tokyo to Honolulu? Right now the result is -19.0
    # it should be 5.0; Honolulu is naturally east of Tokyo, just not so around
    # the date line
    if abs(diff) > 12.0:
        if diff < 0.0:
            diff += 24.0
        else:
            diff -= 24.0
    return diff

如文档中所述,当您扫描一年中的几天时,您可能无法在任何两个给定位置之间获得稳定的结果。但是,实现在当前年份中选择中位数结果的变体是留给读者的练习。

这是另一个解决方案:

from datetime import datetime
from pytz import timezone
from dateutil.relativedelta import relativedelta
utcnow = timezone('utc').localize(datetime.utcnow()) # generic time
here = utcnow.astimezone(timezone('US/Eastern')).replace(tzinfo=None)
there = utcnow.astimezone(timezone('Asia/Ho_Chi_Minh')).replace(tzinfo=None)
offset = relativedelta(here, there) 
offset.hours

在这里,我们要做的是将时间转换为两个不同的时区。然后,我们删除时区信息,以便当您使用相对增量计算两者之间的差异时,我们欺骗它认为这是两个不同的时刻,而不是不同时区的同一时刻。

上述结果将返回 -11,但是此金额可能会在一年中发生变化,因为美国/东部遵守 DST,而亚洲/Ho_Chi_Minh则不遵守。

我创建了两个函数来处理时区。

import datetime
import pytz
def diff_hours_tz(from_tz_name, to_tz_name, negative=False):
    """
    Returns difference hours  between timezones
    res = diff_hours_tz("UTC", "Europe/Paris") : 2
    """
    from_tz = pytz.timezone(from_tz_name)
    to_tz = pytz.timezone(to_tz_name)
    utc_dt = datetime.datetime.now(datetime.timezone.utc)
    dt_from = dt_to = datetime.datetime.utcnow()
    dt_from = from_tz.localize(dt_from)
    dt_to = to_tz.localize(dt_to)
    from_d = dt_from - utc_dt
    if from_d.days < 0:
        return diff_hours_tz(to_tz_name, from_tz_name, True)
    dt_delta = dt_from - dt_to
    negative_int = -1 if negative else 1
    return int(dt_delta.seconds/3600)*negative_int
def dt_tz_to_tz(dt, from_tz_name, to_tz_name):
    """
    Apply difference hours between timezones to a datetime object
    dt_new = dt_tz_to_tz(datetime.datetime.now(), "UTC", "Europe/Paris")
    """
    hours = diff_hours_tz(from_tz_name, to_tz_name)
    return dt+datetime.timedelta(hours=hours)
# Usage example
res = diff_hours_tz("Europe/Paris", "America/New_York")
# Result : -6
res = diff_hours_tz("UTC", "Europe/Paris")
# Result : 2
now = datetime.datetime.now()
# Result : 2019-06-18 15:10:31.720105
dt_new = dt_tz_to_tz(now, "UTC", "Europe/Paris")
# Result : 2019-06-18 17:10:31.720105
dt_new = dt_tz_to_tz(now, "Europe/Paris", "America/New_York")
# Result : 2019-06-18 09:10:31.720105
dt_new = dt_tz_to_tz(now, "America/New_York", "Europe/Paris")
# Result : 2019-06-18 21:10:31.720105

我希望它会有所帮助!

这是一个代码片段,用于获取 UTC 和美国/东部之间的区别,但它应该适用于任何两个时区。

# The following algorithm will work no matter what is the local timezone of the server,
# but for the purposes of this discussion, let's assume that the local timezone is UTC.
local_timestamp = datetime.now()
# Assume that utc_timestamp == 2019-01-01 12:00.
utc_timestamp = pytz.utc.localize(local_timestamp)
# If it was 12:00 in New York, it would be 20:00 in UTC. So us_eastern_timestamp is a UTC
# timestamp with the value of 2019-01-01 20:00.
us_eastern_timestamp = timezone("US/Eastern").localize(local_timestamp).astimezone(pytz.utc)
# delta is a Python timedelta object representing the interval between the two timestamps,
# which, in our example, is -8 hours.
delta = utc_timestamp - us_eastern_timestamp
# In the last line, we convert the timedelta into an integer representing the number of
# hours.
print round(delta.total_seconds() / 60.0 / 60.0)

(tz_from.localize(date) - tz_to.localize(date)).seconds/3600.0

其中tz_from和tz_to是开始和结束时区。 必须指定特定日期。

from datetime import datetime
from zoneinfo import ZoneInfo
dt = datetime.now() # 2020-09-13
tz0, tz1 = "Europe/Berlin", "US/Eastern" # +2 vs. -4 hours rel. to UTC
utcoff0, utcoff1 = dt.astimezone(ZoneInfo(tz0)).utcoffset(), dt.astimezone(ZoneInfo(tz1)).utcoffset()
print(f"hours offset between {tz0} -> {tz1} timezones: {(utcoff1-utcoff0).total_seconds()/3600}")
>>> hours offset between Europe/Berlin -> US/Eastern timezones: -6.0
  • 一种使用 Python 3.9 的标准库执行此操作的方法。

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