blocks|key|837742|text|从Python3.9开始，您可以使用zoneinfo模块。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|837743|首先，让我们使用utcnow()来获得时间|837744|>>>+from+datetime+import+datetime
>>>+database_time+=+datetime.utcnow()
>>>+database_time
datetime.datetime(2021,+9,+24,+4,+18,+27,+706532)|code-block|syntax|javascript|837745|然后创建时区：|837746|>>>+from+zoneinfo+import+ZoneInfo
>>>+utc+=+ZoneInfo('UTC')
>>>+localtz+=+ZoneInfo('localtime')|837747|然后转换。要在时区之间转换，datetime必须知道它所在的时区，然后我们只需使用astimezone()|837748|>>>+utctime+=+database_time.replace(tzinfo=utc)
>>>+localtime+=+utctime.astimezone(localtz)
>>>+localtime
datetime.datetime(2021,+9,+24,+6,+18,+27,+706532,+tzinfo=zoneinfo.ZoneInfo(key='localtime'))|837749|对于Python3.6到3.8，您需要backports.zoneinfo模块：|837750|>>>+try:
>>>+++++from+zoneinfo+import+ZoneInfo
>>>+except+ImportError:
>>>+++++from+backports.zoneinfo+import+ZoneInfo|837751|其余的都是一样的。|837752|对于早于此的版本，则需要pytz或dateutil。datutil的工作原理类似于zoneinfo：|837753|>>>+from+dateutil+import+tz
>>>+utc+=+tz.gettz('UTC')
>>>+localtz+=+tz.tzlocal()

The+Conversion:
>>>+utctime+=+now.replace(tzinfo=UTC)
>>>+localtime+=+utctime.astimezone(localtz)
>>>+localtime
datetime.datetime(2010,+12,+30,+15,+51,+22,+114668,+tzinfo=tzlocal())|837754|pytz有一个不同的接口，这是由于Python的时区处理不能处理不明确的时间：|837755|>>>+import+pytz
>>>+utc+=+pytz.timezone('UTC')
#+There+is+no+local+timezone+support,+you+need+to+know+your+timezone
>>>+localtz+=+pytz.timezone('Europe/Paris')

>>>+utctime+=+utc.localize(database_time)
>>>+localtime+=+localtz.normalize(utctime.astimezone(localtz))
>>>+localtime|837756|entityMap|0|LINK|mutability|MUTABLE|url|http://pypi.python.org/pypi/pytz|1|http://pypi.python.org/pypi/python-dateutil/1.5^0|I|8|0|8|8|0|0|0|0|15|C|0|0|0|0|0|C|4|H|8|C|4|0|H|8|1|0|0|0|4|0|0^^$0|@$1|2|3|4|5|6|7|1I|8|@$9|1J|A|1K|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1L|8|@$9|1M|A|1N|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|1O|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1P|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1Q|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1R|8|@$9|1S|A|1T|B|C]]|D|@]|E|$]]|$1|S|3|T|5|J|7|1U|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1V|8|@]|D|@]|E|$]]|$1|W|3|X|5|J|7|1W|8|@]|D|@]|E|$K|L]]|$1|Y|3|Z|5|6|7|1X|8|@]|D|@]|E|$]]|$1|10|3|11|5|6|7|1Y|8|@$9|1Z|A|20|B|C]|$9|21|A|22|B|C]]|D|@$9|23|A|24|1|25]|$9|26|A|27|1|28]]|E|$]]|$1|12|3|13|5|J|7|29|8|@]|D|@]|E|$K|L]]|$1|14|3|15|5|6|7|2A|8|@$9|2B|A|2C|B|C]]|D|@]|E|$]]|$1|16|3|17|5|J|7|2D|8|@]|D|@]|E|$K|L]]|$1|18|3|-4|5|6|7|2E|8|@]|D|@]|E|$]]]|19|$1A|$5|1B|1C|1D|E|$1E|1F]]|1G|$5|1B|1C|1D|E|$1E|1H]]]]

Since Python 3.9 you can use the <code>zoneinfo</code> module.
First lets get that time with <code>utcnow()</code>:
<pre><code>&gt;&gt;&gt; from datetime import datetime
&gt;&gt;&gt; database_time = datetime.utcnow()
&gt;&gt;&gt; database_time
datetime.datetime(2021, 9, 24, 4, 18, 27, 706532)
</code></pre>
Then create the time zones:
<pre><code>&gt;&gt;&gt; from zoneinfo import ZoneInfo
&gt;&gt;&gt; utc = ZoneInfo('UTC')
&gt;&gt;&gt; localtz = ZoneInfo('localtime')
</code></pre>
Then convert. To convert between timezones, the datetime must know what timezone it is in, then we just use <code>astimezone()</code>:
<pre><code>&gt;&gt;&gt; utctime = database_time.replace(tzinfo=utc)
&gt;&gt;&gt; localtime = utctime.astimezone(localtz)
&gt;&gt;&gt; localtime
datetime.datetime(2021, 9, 24, 6, 18, 27, 706532, tzinfo=zoneinfo.ZoneInfo(key='localtime'))
</code></pre>
For Python 3.6 to 3.8 you need the backports.zoneinfo module:
<pre><code>&gt;&gt;&gt; try:
&gt;&gt;&gt; from zoneinfo import ZoneInfo
&gt;&gt;&gt; except ImportError:
&gt;&gt;&gt; from backports.zoneinfo import ZoneInfo
</code></pre>
The rest is the same.
For versions earlier than that need <a href="http://pypi.python.org/pypi/pytz" rel="nofollow noreferrer"><code>pytz</code></a> or <a href="http://pypi.python.org/pypi/python-dateutil/1.5" rel="nofollow noreferrer"><code>dateutil</code></a>. datutil works similar to zoneinfo:
<pre><code>&gt;&gt;&gt; from dateutil import tz
&gt;&gt;&gt; utc = tz.gettz('UTC')
&gt;&gt;&gt; localtz = tz.tzlocal()

The Conversion:
&gt;&gt;&gt; utctime = now.replace(tzinfo=UTC)
&gt;&gt;&gt; localtime = utctime.astimezone(localtz)
&gt;&gt;&gt; localtime
datetime.datetime(2010, 12, 30, 15, 51, 22, 114668, tzinfo=tzlocal())
</code></pre>
<code>pytz</code> has a different interface which is a result of Python's time zone handling not handling ambigous times:
<pre><code>&gt;&gt;&gt; import pytz
&gt;&gt;&gt; utc = pytz.timezone('UTC')
# There is no local timezone support, you need to know your timezone
&gt;&gt;&gt; localtz = pytz.timezone('Europe/Paris')

&gt;&gt;&gt; utctime = utc.localize(database_time)
&gt;&gt;&gt; localtime = localtz.normalize(utctime.astimezone(localtz))
&gt;&gt;&gt; localtime
</code></pre>

blocks|key|837804|text|我想我弄明白了:计算从纪元开始的秒数，然后使用time.localtime转换为本地时间，然后将时间结构转换回datetime……|type|unstyled|depth|inlineStyleRanges|entityRanges|data|837805|EPOCH_DATETIME+=+datetime.datetime(1970,1,1)
SECONDS_PER_DAY+=+24*60*60

def+utc_to_local_datetime(+utc_datetime+):
++++delta+=+utc_datetime+-+EPOCH_DATETIME
++++utc_epoch+=+SECONDS_PER_DAY+*+delta.days+%2B+delta.seconds
++++time_struct+=+time.localtime(+utc_epoch+)
++++dt_args+=+time_struct[:6]+%2B+(delta.microseconds,)
++++return+datetime.datetime(+*dt_args+)|code-block|syntax|javascript|837806|它正确地应用夏季/冬季DST：|837807|>>>+utc_to_local_datetime(+datetime.datetime(2010,+6,+6,+17,+29,+7,+730000)+)
datetime.datetime(2010,+6,+6,+19,+29,+7,+730000)
>>>+utc_to_local_datetime(+datetime.datetime(2010,+12,+6,+17,+29,+7,+730000)+)
datetime.datetime(2010,+12,+6,+18,+29,+7,+730000)|837808|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I think I figured it out: computes number of seconds since epoch, then converts to a local timzeone using time.localtime, and then converts the time struct back into a datetime...

<pre><code>EPOCH_DATETIME = datetime.datetime(1970,1,1)
SECONDS_PER_DAY = 24*60*60

def utc_to_local_datetime( utc_datetime ):
 delta = utc_datetime - EPOCH_DATETIME
 utc_epoch = SECONDS_PER_DAY * delta.days + delta.seconds
 time_struct = time.localtime( utc_epoch )
 dt_args = time_struct[:6] + (delta.microseconds,)
 return datetime.datetime( *dt_args )
</code></pre>

It applies the summer/winter DST correctly:

<pre><code>&gt;&gt;&gt; utc_to_local_datetime( datetime.datetime(2010, 6, 6, 17, 29, 7, 730000) )
datetime.datetime(2010, 6, 6, 19, 29, 7, 730000)
&gt;&gt;&gt; utc_to_local_datetime( datetime.datetime(2010, 12, 6, 17, 29, 7, 730000) )
datetime.datetime(2010, 12, 6, 18, 29, 7, 730000)
</code></pre>

blocks|key|837856|text|标准的Python库根本没有提供任何tzinfo实现。我一直认为这是datetime模块的一个令人惊讶的缺点。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|837857|documentation+for+the+tzinfo+class确实提供了一些有用的示例。查找本节末尾的大代码块。|837858|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/library/datetime.html#tzinfo-objects^0|I|6|0|0|Y|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@$9|T|A|U|1|V]]|E|$]]|$1|H|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

The standard Python library does not come with any <code>tzinfo</code> implementations at all. I've always considered this a surprising shortcoming of the datetime module.

The <a href="http://docs.python.org/library/datetime.html#tzinfo-objects" rel="nofollow">documentation for the tzinfo class</a> does come with some useful examples. Look for the large code block at the end of the section.

blocks|key|837942|text|在Python+3.3%2B中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|837943|from+datetime+import+datetime,+timezone

def+utc_to_local(utc_dt):
++++return+utc_dt.replace(tzinfo=timezone.utc).astimezone(tz=None)|code-block|syntax|javascript|837944|在Python+2/3中：|837945|import+calendar
from+datetime+import+datetime,+timedelta

def+utc_to_local(utc_dt):
++++#+get+integer+timestamp+to+avoid+precision+lost
++++timestamp+=+calendar.timegm(utc_dt.timetuple())
++++local_dt+=+datetime.fromtimestamp(timestamp)
++++assert+utc_dt.resolution+>=+timedelta(microseconds=1)
++++return+local_dt.replace(microsecond=utc_dt.microsecond)|837946|使用pytz+(都是Python2/3)：|offset|length|style|CODE|837947|import+pytz

local_tz+=+pytz.timezone('Europe/Moscow')+#+use+your+local+timezone+name+here
#+NOTE:+pytz.reference.LocalTimezone()+would+produce+wrong+result+here

##+You+could+use+`tzlocal`+module+to+get+local+timezone+on+Unix+and+Win32
#+from+tzlocal+import+get_localzone+#+$+pip+install+tzlocal

#+#+get+local+timezone++++
#+local_tz+=+get_localzone()

def+utc_to_local(utc_dt):
++++local_dt+=+utc_dt.replace(tzinfo=pytz.utc).astimezone(local_tz)
++++return+local_tz.normalize(local_dt)+#+.normalize+might+be+unnecessary|837948|示例|837949|def+aslocaltimestr(utc_dt):
++++return+utc_to_local(utc_dt).strftime('%25Y-%25m-%25d+%25H:%25M:%25S.%25f+%25Z%25z')

print(aslocaltimestr(datetime(2010,++6,+6,+17,+29,+7,+730000)))
print(aslocaltimestr(datetime(2010,+12,+6,+17,+29,+7,+730000)))
print(aslocaltimestr(datetime.utcnow()))|837950|输出|837951|Python+3.3|837952|2010-06-06+21:29:07.730000+MSD%2B0400
2010-12-06+20:29:07.730000+MSK%2B0300
2012-11-08+14:19:50.093745+MSK%2B0400|837953|Python+2|837954|2010-06-06+21:29:07.730000+
2010-12-06+20:29:07.730000+
2012-11-08+14:19:50.093911+|837955|pytz|837956|2010-06-06+21:29:07.730000+MSD%2B0400
2010-12-06+20:29:07.730000+MSK%2B0300
2012-11-08+14:19:50.146917+MSK%2B0400|837957|注意:它考虑了DST和MSK时区utc偏移量的最新变化。|837958|我不知道非pytz解决方案是否适用于Windows。|837959|entityMap^0|0|0|0|0|2|4|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1G|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1H|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1I|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|1J|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|1K|8|@$M|1L|N|1M|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|1N|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1O|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|1P|8|@]|9|@]|A|$E|F]]|$1|W|3|X|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1R|8|@]|9|@]|A|$]]|$1|10|3|11|5|D|7|1S|8|@]|9|@]|A|$E|F]]|$1|12|3|13|5|6|7|1T|8|@]|9|@]|A|$]]|$1|14|3|15|5|D|7|1U|8|@]|9|@]|A|$E|F]]|$1|16|3|17|5|6|7|1V|8|@]|9|@]|A|$]]|$1|18|3|19|5|D|7|1W|8|@]|9|@]|A|$E|F]]|$1|1A|3|1B|5|6|7|1X|8|@]|9|@]|A|$]]|$1|1C|3|1D|5|6|7|1Y|8|@]|9|@]|A|$]]|$1|1E|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]]|1F|$]]

In Python 3.3+:

<pre><code>from datetime import datetime, timezone

def utc_to_local(utc_dt):
 return utc_dt.replace(tzinfo=timezone.utc).astimezone(tz=None)
</code></pre>

In Python 2/3:

<pre><code>import calendar
from datetime import datetime, timedelta

def utc_to_local(utc_dt):
 # get integer timestamp to avoid precision lost
 timestamp = calendar.timegm(utc_dt.timetuple())
 local_dt = datetime.fromtimestamp(timestamp)
 assert utc_dt.resolution &gt;= timedelta(microseconds=1)
 return local_dt.replace(microsecond=utc_dt.microsecond)
</code></pre>

Using <code>pytz</code> (both Python 2/3):

<pre><code>import pytz

local_tz = pytz.timezone('Europe/Moscow') # use your local timezone name here
# NOTE: pytz.reference.LocalTimezone() would produce wrong result here

## You could use `tzlocal` module to get local timezone on Unix and Win32
# from tzlocal import get_localzone # $ pip install tzlocal

# # get local timezone 
# local_tz = get_localzone()

def utc_to_local(utc_dt):
 local_dt = utc_dt.replace(tzinfo=pytz.utc).astimezone(local_tz)
 return local_tz.normalize(local_dt) # .normalize might be unnecessary
</code></pre>

<h3>Example</h3>

<pre><code>def aslocaltimestr(utc_dt):
 return utc_to_local(utc_dt).strftime('%Y-%m-%d %H:%M:%S.%f %Z%z')

print(aslocaltimestr(datetime(2010, 6, 6, 17, 29, 7, 730000)))
print(aslocaltimestr(datetime(2010, 12, 6, 17, 29, 7, 730000)))
print(aslocaltimestr(datetime.utcnow()))
</code></pre>

<h3>Output</h3>

Python 3.3

<pre><code>2010-06-06 21:29:07.730000 MSD+0400
2010-12-06 20:29:07.730000 MSK+0300
2012-11-08 14:19:50.093745 MSK+0400
</code></pre>

Python 2

<pre><code>2010-06-06 21:29:07.730000 
2010-12-06 20:29:07.730000 
2012-11-08 14:19:50.093911 
</code></pre>

pytz

<pre><code>2010-06-06 21:29:07.730000 MSD+0400
2010-12-06 20:29:07.730000 MSK+0300
2012-11-08 14:19:50.146917 MSK+0400
</code></pre>

Note: it takes into account DST and the recent change of utc offset for MSK timezone.

I don't know whether non-pytz solutions work on Windows.

blocks|key|1052736|text|在Python+2和3中工作的一种简单(但可能有缺陷)的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1052737|import+time
import+datetime

def+utc_to_local(dt):
++++return+dt+-+datetime.timedelta(seconds+=+time.timezone)|code-block|syntax|javascript|1052738|它的优点是编写一个反函数很简单|1052739|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

A simple (but maybe flawed) way that works in Python 2 and 3:

<pre><code>import time
import datetime

def utc_to_local(dt):
 return dt - datetime.timedelta(seconds = time.timezone)
</code></pre>

Its advantage is that it's trivial to write an inverse function

blocks|key|1052762|text|基于阿列克谢的评论。这应该也适用于DST。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1052763|import+time
import+datetime

def+utc_to_local(dt):
++++if+time.localtime().tm_isdst:
++++++++return+dt+-+datetime.timedelta(seconds+=+time.altzone)
++++else:
++++++++return+dt+-+datetime.timedelta(seconds+=+time.timezone)|code-block|syntax|javascript|1052764|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Building on Alexei's comment. This should work for DST too.

<pre><code>import time
import datetime

def utc_to_local(dt):
 if time.localtime().tm_isdst:
 return dt - datetime.timedelta(seconds = time.altzone)
 else:
 return dt - datetime.timedelta(seconds = time.timezone)
</code></pre>

blocks|key|1052826|text|这是另一种在没有min的情况下更改datetime格式时区的方法(我知道我在这上面浪费了精力，但我没有看到这个页面，所以我不知道怎么做)。和秒。因为我的项目不需要它：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1052827|def+change_time_zone(year,+month,+day,+hour):
++++++hour+=+hour+%2B+7+#<--+difference
++++++if+hour+>=+24:
++++++++difference+=+hour+-+24
++++++++hour+=+difference
++++++++day+%2B=+1
++++++++long_months+=+[1,+3,+5,+7,+8,+10,+12]
++++++++short_months+=+[4,+6,+9,+11]
++++++++if+month+in+short_months:
++++++++++if+day+>=+30:
++++++++++++day+=+1
++++++++++++month+%2B=+1
++++++++++++if+month+>+12:
++++++++++++++year+%2B=+1
++++++++elif+month+in+long_months:
++++++++++if+day+>=+31:
++++++++++++day+=+1
++++++++++++month+%2B=+1
++++++++++++if+month+>+12:
++++++++++++++year+%2B=+1
++++++++elif+month+==+2:
++++++++++if+not+year%254==0:
++++++++++++if+day+>=+29:
++++++++++++++day+=+1
++++++++++++++month+%2B=+1
++++++++++++++if+month+>+12:
++++++++++++++++year+%2B=+1
++++++++++else:
++++++++++++if+day+>=+28:
++++++++++++++day+=+1
++++++++++++++month+%2B=+1
++++++++++++++if+month+>+12:
++++++++++++++++year+%2B=+1
++++++return+datetime(int(year),+int(month),+int(day),+int(hour),+00)|code-block|syntax|javascript|1052828|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is another way to change timezone in datetime format (I know I wasted my energy on this but I didn't see this page so I don't know how) without min. and sec. cause I don't need it for my project:

<pre><code>def change_time_zone(year, month, day, hour):
 hour = hour + 7 #&lt;-- difference
 if hour &gt;= 24:
 difference = hour - 24
 hour = difference
 day += 1
 long_months = [1, 3, 5, 7, 8, 10, 12]
 short_months = [4, 6, 9, 11]
 if month in short_months:
 if day &gt;= 30:
 day = 1
 month += 1
 if month &gt; 12:
 year += 1
 elif month in long_months:
 if day &gt;= 31:
 day = 1
 month += 1
 if month &gt; 12:
 year += 1
 elif month == 2:
 if not year%4==0:
 if day &gt;= 29:
 day = 1
 month += 1
 if month &gt; 12:
 year += 1
 else:
 if day &gt;= 28:
 day = 1
 month += 1
 if month &gt; 12:
 year += 1
 return datetime(int(year), int(month), int(day), int(hour), 00)
</code></pre>

blocks|key|1052860|text|这是一种可怕的方式，但它避免了创建定义。它满足了坚持使用基本Python3库的要求。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1052861|#+Adjust+from+UST+to+Eastern+Standard+Time+(dynamic)
#+df.my_localtime+should+already+be+in+datetime+format,+so+just+in+case
df['my_localtime']+=+pd.to_datetime.df['my_localtime']

df['my_localtime']+=+df['my_localtime'].dt.tz_localize('UTC').dt.tz_convert('America/New_York').astype(str)
df['my_localtime']+=+pd.to_datetime(df.my_localtime.str[:-6])|code-block|syntax|javascript|1052862|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This is a terrible way to do it but it avoids creating a definition. It fulfills the requirement to stick with the basic Python3 library.

<pre><code># Adjust from UST to Eastern Standard Time (dynamic)
# df.my_localtime should already be in datetime format, so just in case
df['my_localtime'] = pd.to_datetime.df['my_localtime']

df['my_localtime'] = df['my_localtime'].dt.tz_localize('UTC').dt.tz_convert('America/New_York').astype(str)
df['my_localtime'] = pd.to_datetime(df.my_localtime.str[:-6])
</code></pre>

blocks|key|838205|text|使用timedelta在时区之间切换。你所需要的就是时区之间的时差。不必为datetime对象的所有6个元素设置边界。timedelta也可以轻松处理闰年、闰世纪等。你必须先|type|unstyled|depth|inlineStyleRanges|entityRanges|data|838206|from+datetime+import+datetime,+timedelta|code-block|syntax|javascript|838207|然后，如果offset是以小时为单位的时区增量：|offset|length|style|CODE|838208|timeout+=+timein+%2B+timedelta(hours+=+offset)|838209|其中timein和timeout是datetime对象。例如：|838210|timein+%2B+timedelta(hours+=+-8)|838211|从GMT转换为PST。|838212|那么，如何确定offset呢？这里有一个简单的函数，假设您只有几个转换的可能性，而不使用datetime对象，这些对象是时区“感知”的，一些其他答案很好地做到了这一点。有点手动，但有时清晰是最好的。|838213|def+change_timezone(timein,+timezone,+timezone_out):
++++'''
++++changes+timezone+between+predefined+timezone+offsets+to+GMT
++++timein+-+datetime+object
++++timezone+-+'PST',+'PDT',+'GMT'+(can+add+more+as+needed)
++++timezone_out+-+'PST',+'PDT',+'GMT'+(can+add+more+as+needed)
++++'''+
++++#+simple+table+lookup++++++++
++++tz_offset+=++{'PST':+{'GMT':+8,+'PDT':+1,+'PST':+0},+\
++++++++++++++++++'GMT':+{'PST':+-8,+'PDT':+-7,+'GMT':+0},+\
++++++++++++++++++'PDT':+{'GMT':+7,+'PST':+-1,+'PDT':+0}}
++++try:
++++++++offset+=+tz_offset[timezone][timezone_out]
++++except:
++++++++msg+=+'Input+timezone='+%2B+timezone+%2B+'+OR+output+time+zone='+%2B+\
++++++++++++timezone_out+%2B+'+not+recognized'
++++++++raise+DateTimeError(msg)

++++return+timein+%2B+timedelta(hours+=+offset)|838214|在看了大量的答案和我所能想到的最紧凑的代码之后(目前)，似乎最好的做法是所有的应用程序，其中时间很重要，并且必须考虑混合时区，应该真正努力使所有的datetime对象“意识到”。那么看起来最简单的答案是：|838215|timeout+=+timein.astimezone(pytz.timezone("GMT"))|838216|例如，转换为GMT。当然，要在任何其他时区之间进行转换，无论是本地时区还是其他时区，只需使用pytz能够理解的适当时区字符串(来自pytz.all_timezones)。然后，夏令时也被考虑在内。|838217|entityMap^0|0|0|5|6|0|0|18|0|0|0|U|0|0|7|6|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|18|8|@$I|19|J|1A|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|1B|8|@$I|1C|J|1D|K|L]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1E|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1F|8|@$I|1G|J|1H|K|L]]|9|@]|A|$]]|$1|S|3|T|5|6|7|1I|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1J|8|@$I|1K|J|1L|K|L]]|9|@]|A|$]]|$1|W|3|X|5|D|7|1M|8|@]|9|@]|A|$E|F]]|$1|Y|3|Z|5|6|7|1N|8|@]|9|@]|A|$]]|$1|10|3|11|5|D|7|1O|8|@]|9|@]|A|$E|F]]|$1|12|3|13|5|6|7|1P|8|@]|9|@]|A|$]]|$1|14|3|-4|5|6|7|1Q|8|@]|9|@]|A|$]]]|15|$]]

Use timedelta to switch between timezones. All you need is the offset in hours between timezones. Don't have to fiddle with boundaries for all 6 elements of a datetime object. timedelta handles leap years, leap centuries, etc., too, with ease. You must first 

<pre><code>from datetime import datetime, timedelta
</code></pre>

Then if <code>offset</code> is the timezone delta in hours: 

<code>timeout = timein + timedelta(hours = offset)</code> 

where timein and timeout are datetime objects. e.g. 

<code>timein + timedelta(hours = -8)</code> 

converts from GMT to PST.

So, how to determine <code>offset</code>? Here is a simple function provided you only have a few possibilities for conversion without using datetime objects that are timezone "aware" which some other answers nicely do. A bit manual, but sometimes clarity is best.

<pre><code>def change_timezone(timein, timezone, timezone_out):
 '''
 changes timezone between predefined timezone offsets to GMT
 timein - datetime object
 timezone - 'PST', 'PDT', 'GMT' (can add more as needed)
 timezone_out - 'PST', 'PDT', 'GMT' (can add more as needed)
 ''' 
 # simple table lookup 
 tz_offset = {'PST': {'GMT': 8, 'PDT': 1, 'PST': 0}, \
 'GMT': {'PST': -8, 'PDT': -7, 'GMT': 0}, \
 'PDT': {'GMT': 7, 'PST': -1, 'PDT': 0}}
 try:
 offset = tz_offset[timezone][timezone_out]
 except:
 msg = 'Input timezone=' + timezone + ' OR output time zone=' + \
 timezone_out + ' not recognized'
 raise DateTimeError(msg)

 return timein + timedelta(hours = offset)
</code></pre>

After looking at the numerous answers and playing around with the tightest code I can think of (for now) it seems best that all applications, where time is important and mixed timezones must be accounted for, should make a real effort to make all datetime objects "aware". Then it would seem the simplest answer is:

<pre><code>timeout = timein.astimezone(pytz.timezone("GMT"))
</code></pre>

to convert to GMT for example. Of course, to convert to/from any other timezone you wish, local or otherwise, just use the appropriate timezone string that pytz understands (from pytz.all_timezones). Daylight savings time is then also taken into account.

blocks|key|1052975|text|使用time.timezone，它给出一个“协调世界时以西秒”的整数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1052976|例如：|1052977|from+datetime+import+datetime,+timedelta,+timezone
import+time

#+make+datetime+from+timestamp,+thus+no+timezone+info+is+attached
now+=+datetime.fromtimestamp(time.time())

#+make+local+timezone+with+time.timezone
local_tz+=+timezone(timedelta(seconds=-time.timezone))

#+attach+different+timezones+as+you+wish
utc_time+=+now.astimezone(timezone.utc)
local_time+=+now.astimezone(local_tz)

print(utc_time.isoformat(timespec='seconds'))+
print(local_time.isoformat(timespec='seconds'))|code-block|syntax|javascript|1052978|在我的PC+(Python+3.7.3)上，它提供了：|1052979|2021-05-07T12:50:46%2B00:00
2021-05-07T20:50:46%2B08:00|1052980|非常简单，只使用标准库~|1052981|entityMap^0|2|D|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|11|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|T|$]]

Use <code>time.timezone</code>, it gives an integer in &quot;seconds west of UTC&quot;.
For example:
<pre class="lang-py prettyprint-override"><code>from datetime import datetime, timedelta, timezone
import time

# make datetime from timestamp, thus no timezone info is attached
now = datetime.fromtimestamp(time.time())

# make local timezone with time.timezone
local_tz = timezone(timedelta(seconds=-time.timezone))

# attach different timezones as you wish
utc_time = now.astimezone(timezone.utc)
local_time = now.astimezone(local_tz)

print(utc_time.isoformat(timespec='seconds')) 
print(local_time.isoformat(timespec='seconds'))
</code></pre>
On my PC (Python 3.7.3), it gives:
<pre><code>2021-05-07T12:50:46+00:00
2021-05-07T20:50:46+08:00
</code></pre>
Pretty simple and uses only standard libraries~

blocks|key|838298|text|对于特定的情况：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|838299|输入utc日期时间字符串。//通常来自日志|838300|输出区域设置日期时间字符串。|838301|​|838302|def+utc_to_locale(utc_str):
++++#+from+utc+to+locale
++++d1=datetime.fromisoformat(utc_str%2B'-00:00')
++++return+d1.astimezone().strftime('%25F+%25T.%25f')[:-3]|code-block|syntax|javascript|838303|838304|测试：|838305|>>>+utc_to_locale('2022-02-14+00:49:06')
'2022-02-14+08:49:06.000'
>>>+utc_to_locale('2022-02-14+00:49:06.123')
'2022-02-14+08:49:06.123'
>>>+utc_to_locale('2022-02-14T00:49:06.123')
'2022-02-14+08:49:06.123'|838306|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|X|8|@]|9|@]|A|$K|L]]|$1|M|3|G|5|6|7|Y|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|Z|8|@]|9|@]|A|$]]|$1|P|3|Q|5|J|7|10|8|@]|9|@]|A|$K|L]]|$1|R|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|S|$]]

for a specific situation: 
　input utc datetime string. // usually from log 
　output locale datetime string.
 
<pre class="lang-py prettyprint-override"><code>def utc_to_locale(utc_str):
 # from utc to locale
 d1=datetime.fromisoformat(utc_str+'-00:00')
 return d1.astimezone().strftime('%F %T.%f')[:-3]
</code></pre>
 
tests:
<pre><code>&gt;&gt;&gt; utc_to_locale('2022-02-14 00:49:06')
'2022-02-14 08:49:06.000'
&gt;&gt;&gt; utc_to_locale('2022-02-14 00:49:06.123')
'2022-02-14 08:49:06.123'
&gt;&gt;&gt; utc_to_locale('2022-02-14T00:49:06.123')
'2022-02-14 08:49:06.123'
</code></pre>

I have a python <code>datetime</code> instance that was created using <code>datetime.utcnow()</code> and persisted in database.
For display, I would like to convert the <code>datetime</code> instance retrieved from the database to local <code>datetime</code> using the default local timezone (i.e., as if the <code>datetime</code> was created using <code>datetime.now()</code>).
How can I convert the UTC <code>datetime</code> to a local <code>datetime</code> using only python standard library (e.g., no <code>pytz</code> dependency)?
It seems one solution would be to use <code>datetime.astimezone(tz)</code>, but how would you get the default local timezone?

How to convert a UTC datetime to a local datetime using only standard library?

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我有一个使用datetime.utcnow()创建并持久存储在数据库中的python datetime实例。为了便于显示，我想将从数据库检索到的datetime实例转换为使用默认本地时区的本地datetime (即，就好像datetime是使用datetime.now()创建的一样)。如何仅使用python标准库(例如...

问如何仅使用标准库将UTC日期时间转换为本地日期时间？
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