Pandas timestamp 和 python datetime 对时区的解释不同

Question

我不明白为什么 a 和 b 不一样:

import pandas as pd
from datetime import datetime
import pytz

here = pytz.timezone('Europe/Amsterdam')

a = pd.Timestamp('2018-4-9', tz=here).to_pydatetime() 
# datetime.datetime(2018, 4, 9, 0, 0, tzinfo=<DstTzInfo'Europe/Amsterdam' CEST+2:00:00 DST>)
b = datetime(2018, 4, 9, 0, tzinfo=here)
# datetime.datetime(2018, 4, 9, 0, 0, tzinfo=<DstTzInfo 'Europe/Amsterdam' LMT+0:20:00 STD>)

print(b-a)
# returns 01:40:00

Answer 1

从这里stackoverflow post我了解到 tzinfo 对于某些时区效果不佳，这可能是导致错误结果的原因。 pytz doc :

Unfortunately using the tzinfo argument of the standard datetime constructors ‘’does not work’’ with pytz for many timezones.

解决方案是使用localize 或astimezone:

import pandas as pd
from datetime import datetime
import pytz

here = pytz.timezone('Europe/Amsterdam')

a = pd.Timestamp('2018-4-9', tz=here).to_pydatetime() 
# datetime.datetime(2018, 4, 9, 0, 0, tzinfo=<DstTzInfo'Europe/Amsterdam' CEST+2:00:00 DST>)
b = here.localize(datetime(2018, 4, 9))
# datetime.datetime(2018, 4, 9, 0, 0, tzinfo=<DstTzInfo 'Europe/Amsterdam' CEST+2:00:00 DST>)

print(b-a)
# returns 00:00:00