在Python中将datetime.date转换为UTC时间戳

问题:在Python中将datetime.date转换为UTC时间戳

我正在使用Python处理日期,因此需要将其转换为UTC时间戳以在Javascript中使用。以下代码不起作用:

>>> d = datetime.date(2011,01,01)
>>> datetime.datetime.utcfromtimestamp(time.mktime(d.timetuple()))
datetime.datetime(2010, 12, 31, 23, 0)

首先将日期对象转换为datetime也无济于事。我从以下链接尝试了此示例,但是:

from pytz import utc, timezone
from datetime import datetime
from time import mktime
input_date = datetime(year=2011, month=1, day=15)

现在要么:

mktime(utc.localize(input_date).utctimetuple())

要么

mktime(timezone('US/Eastern').localize(input_date).utctimetuple())

确实有效。

如此普遍的问题:如何根据UTC将日期转换为自纪元以来的秒数?

I am dealing with dates in Python and I need to convert them to UTC timestamps to be used inside Javascript. The following code does not work:

>>> d = datetime.date(2011,01,01)
>>> datetime.datetime.utcfromtimestamp(time.mktime(d.timetuple()))
datetime.datetime(2010, 12, 31, 23, 0)

Converting the date object first to datetime also does not help. I tried the example at this link from, but:

from pytz import utc, timezone
from datetime import datetime
from time import mktime
input_date = datetime(year=2011, month=1, day=15)

and now either:

mktime(utc.localize(input_date).utctimetuple())

or

mktime(timezone('US/Eastern').localize(input_date).utctimetuple())

does work.

So general question: how can I get a date converted to seconds since epoch according to UTC?


回答 0

如果d = date(2011, 1, 1)使用UTC:

>>> from datetime import datetime, date
>>> import calendar
>>> timestamp1 = calendar.timegm(d.timetuple())
>>> datetime.utcfromtimestamp(timestamp1)
datetime.datetime(2011, 1, 1, 0, 0)

如果d在当地时区:

>>> import time
>>> timestamp2 = time.mktime(d.timetuple()) # DO NOT USE IT WITH UTC DATE
>>> datetime.fromtimestamp(timestamp2)
datetime.datetime(2011, 1, 1, 0, 0)

timestamp1timestamp2如果午夜在本地时区是不一样的时间实例作为午夜UTC可能会有所不同。

mktime()如果d对应于一个不明确的本地时间(例如,在DST过渡期间),或者d是utc偏移可能已经不同并且 C mktime()无法访问给定平台上的tz数据库的过去(未来)日期,则可能返回错误结果。您可以使用pytz模块(例如via tzlocal.get_localzone())来访问所有平台上的tz数据库。此外,如果使用timezone,则utcfromtimestamp()可能会失败并mktime()可能返回非POSIX时间戳"right"


要转换datetime.date不使用UTC表示日期的对象calendar.timegm()

DAY = 24*60*60 # POSIX day in seconds (exact value)
timestamp = (utc_date.toordinal() - date(1970, 1, 1).toordinal()) * DAY
timestamp = (utc_date - date(1970, 1, 1)).days * DAY

如何根据UTC将日期转换为自纪元以来的秒数?

将已经以UTC表示时间的对象datetime.datetime(不是datetime.date)转换为相应的POSIX时间戳(a float)。

Python 3.3以上

datetime.timestamp()

from datetime import timezone

timestamp = dt.replace(tzinfo=timezone.utc).timestamp()

注意:有必要timezone.utc明确地提供其他条件,.timestamp()假设您朴素的datetime对象位于本地时区。

Python 3(<3.3)

从文档中获取datetime.utcfromtimestamp()

没有从日期时间实例获取时间戳的方法,但是可以很容易地如下计算对应于日期时间实例dt的POSIX时间戳。对于幼稚的dt:

timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1)

对于有意识的dt:

timestamp = (dt - datetime(1970,1,1, tzinfo=timezone.utc)) / timedelta(seconds=1)

有趣的读物:大纪元时间与一天中的时间之间的时差是几点?多少秒过去了?

另请参见:datetime需要一种“时代”方法

Python 2

为了使以上代码适用于Python 2:

timestamp = (dt - datetime(1970, 1, 1)).total_seconds()

其中timedelta.total_seconds()等于在(td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6启用真除法的情况下进行的计算。

from __future__ import division
from datetime import datetime, timedelta

def totimestamp(dt, epoch=datetime(1970,1,1)):
    td = dt - epoch
    # return td.total_seconds()
    return (td.microseconds + (td.seconds + td.days * 86400) * 10**6) / 10**6 

now = datetime.utcnow()
print now
print totimestamp(now)

当心浮点问题

输出量

2012-01-08 15:34:10.022403
1326036850.02

如何将感知datetime对象转换为POSIX时间戳

assert dt.tzinfo is not None and dt.utcoffset() is not None
timestamp = dt.timestamp() # Python 3.3+

在Python 3上:

from datetime import datetime, timedelta, timezone

epoch = datetime(1970, 1, 1, tzinfo=timezone.utc)
timestamp = (dt - epoch) / timedelta(seconds=1)
integer_timestamp = (dt - epoch) // timedelta(seconds=1)

在Python 2上:

# utc time = local time              - utc offset
utc_naive  = dt.replace(tzinfo=None) - dt.utcoffset()
timestamp = (utc_naive - datetime(1970, 1, 1)).total_seconds()

If d = date(2011, 1, 1) is in UTC:

>>> from datetime import datetime, date
>>> import calendar
>>> timestamp1 = calendar.timegm(d.timetuple())
>>> datetime.utcfromtimestamp(timestamp1)
datetime.datetime(2011, 1, 1, 0, 0)

If d is in local timezone:

>>> import time
>>> timestamp2 = time.mktime(d.timetuple()) # DO NOT USE IT WITH UTC DATE
>>> datetime.fromtimestamp(timestamp2)
datetime.datetime(2011, 1, 1, 0, 0)

timestamp1 and timestamp2 may differ if midnight in the local timezone is not the same time instance as midnight in UTC.

mktime() may return a wrong result if d corresponds to an ambiguous local time (e.g., during DST transition) or if d is a past(future) date when the utc offset might have been different and the C mktime() has no access to the tz database on the given platform. You could use pytz module (e.g., via tzlocal.get_localzone()) to get access to the tz database on all platforms. Also, utcfromtimestamp() may fail and mktime() may return non-POSIX timestamp if "right" timezone is used.


To convert datetime.date object that represents date in UTC without calendar.timegm():

DAY = 24*60*60 # POSIX day in seconds (exact value)
timestamp = (utc_date.toordinal() - date(1970, 1, 1).toordinal()) * DAY
timestamp = (utc_date - date(1970, 1, 1)).days * DAY

How can I get a date converted to seconds since epoch according to UTC?

To convert datetime.datetime (not datetime.date) object that already represents time in UTC to the corresponding POSIX timestamp (a float).

Python 3.3+

datetime.timestamp():

from datetime import timezone

timestamp = dt.replace(tzinfo=timezone.utc).timestamp()

Note: It is necessary to supply timezone.utc explicitly otherwise .timestamp() assume that your naive datetime object is in local timezone.

Python 3 (< 3.3)

From the docs for datetime.utcfromtimestamp():

There is no method to obtain the timestamp from a datetime instance, but POSIX timestamp corresponding to a datetime instance dt can be easily calculated as follows. For a naive dt:

timestamp = (dt - datetime(1970, 1, 1)) / timedelta(seconds=1)

And for an aware dt:

timestamp = (dt - datetime(1970,1,1, tzinfo=timezone.utc)) / timedelta(seconds=1)

Interesting read: Epoch time vs. time of day on the difference between What time is it? and How many seconds have elapsed?

See also: datetime needs an “epoch” method

Python 2

To adapt the above code for Python 2:

timestamp = (dt - datetime(1970, 1, 1)).total_seconds()

where timedelta.total_seconds() is equivalent to (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6 computed with true division enabled.

Example

from __future__ import division
from datetime import datetime, timedelta

def totimestamp(dt, epoch=datetime(1970,1,1)):
    td = dt - epoch
    # return td.total_seconds()
    return (td.microseconds + (td.seconds + td.days * 86400) * 10**6) / 10**6 

now = datetime.utcnow()
print now
print totimestamp(now)

Beware of floating-point issues.

Output

2012-01-08 15:34:10.022403
1326036850.02

How to convert an aware datetime object to POSIX timestamp

assert dt.tzinfo is not None and dt.utcoffset() is not None
timestamp = dt.timestamp() # Python 3.3+

On Python 3:

from datetime import datetime, timedelta, timezone

epoch = datetime(1970, 1, 1, tzinfo=timezone.utc)
timestamp = (dt - epoch) / timedelta(seconds=1)
integer_timestamp = (dt - epoch) // timedelta(seconds=1)

On Python 2:

# utc time = local time              - utc offset
utc_naive  = dt.replace(tzinfo=None) - dt.utcoffset()
timestamp = (utc_naive - datetime(1970, 1, 1)).total_seconds()

回答 1

适用于Unix系统

>>> import datetime
>>> d = datetime.date(2011,01,01)
>>> d.strftime("%s")  # <-- THIS IS THE CODE YOU WANT
'1293832800'

注1: dizzyf观察到这适用于本地时区。不要在生产中使用。

注意2: JakubNarębski指出,即使对于具有偏移量的日期时间,它也会忽略时区信息(已针对Python 2.7测试)。

For unix systems only:

>>> import datetime
>>> d = datetime.date(2011,01,01)
>>> d.strftime("%s")  # <-- THIS IS THE CODE YOU WANT
'1293832800'

Note 1: dizzyf observed that this applies localized timezones. Don’t use in production.

Note 2: Jakub Narębski noted that this ignores timezone information even for offset-aware datetime (tested for Python 2.7).


回答 2

  • 假设1:您正在尝试将日期转换为时间戳,但是由于日期涵盖24小时,因此没有一个代表该日期的时间戳。我假设您要代表该日期的时间戳记为午夜(00:00:00.000)。

  • 假设2:您提供的日期与特定时区没有关联,但是您想确定与特定时区(UTC)的偏移量。如果不知道日期所在的时区,就无法为特定时区计算时间戳。我假设您想将日期当作本地​​系统时区中的日期。

首先,您可以使用timetuple()成员将日期实例转换为代表各种时间成分的元组:

dtt = d.timetuple() # time.struct_time(tm_year=2011, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=5, tm_yday=1, tm_isdst=-1)

然后,您可以使用将该时间戳转换为时间戳time.mktime

ts = time.mktime(dtt) # 1293868800.0

您可以通过使用纪元时间本身(1970-01-01)对其进行测试来验证此方法,在这种情况下,该函数应返回该日期的本地时区的时区偏移量:

d = datetime.date(1970,1,1)
dtt = d.timetuple() # time.struct_time(tm_year=1970, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=1, tm_isdst=-1)
ts = time.mktime(dtt) # 28800.0

28800.0 是8个小时,这对于太平洋时区(我所在的时间)是正确的。

  • Assumption 1: You’re attempting to convert a date to a timestamp, however since a date covers a 24 hour period, there isn’t a single timestamp that represents that date. I’ll assume that you want to represent the timestamp of that date at midnight (00:00:00.000).

  • Assumption 2: The date you present is not associated with a particular time zone, however you want to determine the offset from a particular time zone (UTC). Without knowing the time zone the date is in, it isn’t possible to calculate a timestamp for a specific time zone. I’ll assume that you want to treat the date as if it is in the local system time zone.

First, you can convert the date instance into a tuple representing the various time components using the timetuple() member:

dtt = d.timetuple() # time.struct_time(tm_year=2011, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=5, tm_yday=1, tm_isdst=-1)

You can then convert that into a timestamp using time.mktime:

ts = time.mktime(dtt) # 1293868800.0

You can verify this method by testing it with the epoch time itself (1970-01-01), in which case the function should return the timezone offset for the local time zone on that date:

d = datetime.date(1970,1,1)
dtt = d.timetuple() # time.struct_time(tm_year=1970, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=1, tm_isdst=-1)
ts = time.mktime(dtt) # 28800.0

28800.0 is 8 hours, which would be correct for the Pacific time zone (where I’m at).


回答 3

按照python2.7文档,您必须使用calendar.timegm()而不是time.mktime()

>>> d = datetime.date(2011,01,01)
>>> datetime.datetime.utcfromtimestamp(calendar.timegm(d.timetuple()))
datetime.datetime(2011, 1, 1, 0, 0)

follow the python2.7 document, you have to use calendar.timegm() instead of time.mktime()

>>> d = datetime.date(2011,01,01)
>>> datetime.datetime.utcfromtimestamp(calendar.timegm(d.timetuple()))
datetime.datetime(2011, 1, 1, 0, 0)

回答 4

我定义了我自己的两个功能

  • utc_time2datetime(utc_time,tz =无)
  • datetime2utc_time(日期时间)

这里:

import time
import datetime
from pytz import timezone
import calendar
import pytz


def utc_time2datetime(utc_time, tz=None):
    # convert utc time to utc datetime
    utc_datetime = datetime.datetime.fromtimestamp(utc_time)

    # add time zone to utc datetime
    if tz is None:
        tz_datetime = utc_datetime.astimezone(timezone('utc'))
    else:
        tz_datetime = utc_datetime.astimezone(tz)

    return tz_datetime


def datetime2utc_time(datetime):
    # add utc time zone if no time zone is set
    if datetime.tzinfo is None:
        datetime = datetime.replace(tzinfo=timezone('utc'))

    # convert to utc time zone from whatever time zone the datetime is set to
    utc_datetime = datetime.astimezone(timezone('utc')).replace(tzinfo=None)

    # create a time tuple from datetime
    utc_timetuple = utc_datetime.timetuple()

    # create a time element from the tuple an add microseconds
    utc_time = calendar.timegm(utc_timetuple) + datetime.microsecond / 1E6

    return utc_time

I defined my own two functions

  • utc_time2datetime(utc_time, tz=None)
  • datetime2utc_time(datetime)

here:

import time
import datetime
from pytz import timezone
import calendar
import pytz


def utc_time2datetime(utc_time, tz=None):
    # convert utc time to utc datetime
    utc_datetime = datetime.datetime.fromtimestamp(utc_time)

    # add time zone to utc datetime
    if tz is None:
        tz_datetime = utc_datetime.astimezone(timezone('utc'))
    else:
        tz_datetime = utc_datetime.astimezone(tz)

    return tz_datetime


def datetime2utc_time(datetime):
    # add utc time zone if no time zone is set
    if datetime.tzinfo is None:
        datetime = datetime.replace(tzinfo=timezone('utc'))

    # convert to utc time zone from whatever time zone the datetime is set to
    utc_datetime = datetime.astimezone(timezone('utc')).replace(tzinfo=None)

    # create a time tuple from datetime
    utc_timetuple = utc_datetime.timetuple()

    # create a time element from the tuple an add microseconds
    utc_time = calendar.timegm(utc_timetuple) + datetime.microsecond / 1E6

    return utc_time

回答 5

这个问题有点困惑。时间戳不是UTC,而是Unix。日期可能是UTC?假设是这样,并且如果您使用的是Python 3.2+,则简单日期使此操作变得无关紧要:

>>> SimpleDate(date(2011,1,1), tz='utc').timestamp
1293840000.0

如果您实际上有年,月和日,则无需创建date

>>> SimpleDate(2011,1,1, tz='utc').timestamp
1293840000.0

以及日期是否在其他时区中(这很重要,因为我们假设午夜没有相关的时间):

>>> SimpleDate(date(2011,1,1), tz='America/New_York').timestamp
1293858000.0

[simple-date背后的想法是将所有python的日期和时间收集在一个一致的类中,因此您可以进行任何转换。因此,例如,它也会沿相反方向前进:

>>> SimpleDate(1293858000, tz='utc').date
datetime.date(2011, 1, 1)

]

the question is a little confused. timestamps are not UTC – they’re a Unix thing. the date might be UTC? assuming it is, and if you’re using Python 3.2+, simple-date makes this trivial:

>>> SimpleDate(date(2011,1,1), tz='utc').timestamp
1293840000.0

if you actually have the year, month and day you don’t need to create the date:

>>> SimpleDate(2011,1,1, tz='utc').timestamp
1293840000.0

and if the date is in some other timezone (this matters because we’re assuming midnight without an associated time):

>>> SimpleDate(date(2011,1,1), tz='America/New_York').timestamp
1293858000.0

[the idea behind simple-date is to collect all python’s date and time stuff in one consistent class, so you can do any conversion. so, for example, it will also go the other way:

>>> SimpleDate(1293858000, tz='utc').date
datetime.date(2011, 1, 1)

]


回答 6

使用箭头包:

>>> import arrow
>>> arrow.get(2010, 12, 31).timestamp
1293753600
>>> time.gmtime(1293753600)
time.struct_time(tm_year=2010, tm_mon=12, tm_mday=31, 
    tm_hour=0, tm_min=0, tm_sec=0, 
    tm_wday=4, tm_yday=365, tm_isdst=0)

Using the arrow package:

>>> import arrow
>>> arrow.get(2010, 12, 31).timestamp
1293753600
>>> time.gmtime(1293753600)
time.struct_time(tm_year=2010, tm_mon=12, tm_mday=31, 
    tm_hour=0, tm_min=0, tm_sec=0, 
    tm_wday=4, tm_yday=365, tm_isdst=0)

回答 7

完整的时间字符串包含:

  • 日期
  • 时间
  • utcoffset [+HHMM or -HHMM]

例如:

1970-01-01 06:00:00 +0500 == 1970-01-01 01:00:00 +0000 == UNIX timestamp:3600

$ python3
>>> from datetime import datetime
>>> from calendar import timegm
>>> tm = '1970-01-01 06:00:00 +0500'
>>> fmt = '%Y-%m-%d %H:%M:%S %z'
>>> timegm(datetime.strptime(tm, fmt).utctimetuple())
3600

注意:

UNIX timestamp是一个浮点数,以纪元以来的秒数表示,单位为UTC


编辑:

$ python3
>>> from datetime import datetime, timezone, timedelta
>>> from calendar import timegm
>>> dt = datetime(1970, 1, 1, 6, 0)
>>> tz = timezone(timedelta(hours=5))
>>> timegm(dt.replace(tzinfo=tz).utctimetuple())
3600

A complete time-string contains:

  • date
  • time
  • utcoffset [+HHMM or -HHMM]

For example:

1970-01-01 06:00:00 +0500 == 1970-01-01 01:00:00 +0000 == UNIX timestamp:3600

$ python3
>>> from datetime import datetime
>>> from calendar import timegm
>>> tm = '1970-01-01 06:00:00 +0500'
>>> fmt = '%Y-%m-%d %H:%M:%S %z'
>>> timegm(datetime.strptime(tm, fmt).utctimetuple())
3600

Note:

UNIX timestamp is a floating point number expressed in seconds since the epoch, in UTC.


Edit:

$ python3
>>> from datetime import datetime, timezone, timedelta
>>> from calendar import timegm
>>> dt = datetime(1970, 1, 1, 6, 0)
>>> tz = timezone(timedelta(hours=5))
>>> timegm(dt.replace(tzinfo=tz).utctimetuple())
3600

回答 8

考虑到您有一个datetime名为的对象d,请使用以下命令获取UTC中的时间戳记:

d.strftime("%Y-%m-%dT%H:%M:%S.%fZ")

对于相反的方向,请使用以下命令:

d = datetime.strptime("2008-09-03T20:56:35.450686Z", "%Y-%m-%dT%H:%M:%S.%fZ")

Considering you have a datetime object called d, use the following to get the timestamp in UTC:

d.strftime("%Y-%m-%dT%H:%M:%S.%fZ")

And for the opposite direction, use following :

d = datetime.strptime("2008-09-03T20:56:35.450686Z", "%Y-%m-%dT%H:%M:%S.%fZ")

回答 9

我对深入的讨论印象深刻。

我的2美分:

从datetime导入datetime导入时间

utc中的时间戳为:

timestamp = \
(datetime.utcnow() - datetime(1970,1,1)).total_seconds()

要么,

timestamp = time.time()

如果现在是从datetime.now()返回的,则在同一DST中

utcoffset = (datetime.now() - datetime.utcnow()).total_seconds()
timestamp = \
(now - datetime(1970,1,1)).total_seconds() - utcoffset

i’m impressed of the deep discussion.

my 2 cents:

from datetime import datetime import time

the timestamp in utc is:

timestamp = \
(datetime.utcnow() - datetime(1970,1,1)).total_seconds()

or,

timestamp = time.time()

if now results from datetime.now(), in the same DST

utcoffset = (datetime.now() - datetime.utcnow()).total_seconds()
timestamp = \
(now - datetime(1970,1,1)).total_seconds() - utcoffset