東部和格林威治標準時間之間的轉換錯誤

Question

我在將以下時間從東部轉換爲UTC/GMT時出現了一個奇怪的問題。有人可以建議嗎？

>>> import datetime 
>>> import pytz 
>>> 
>>> ept_time = datetime.datetime(2014,03,21,7) # March 21st at 7am 
>>> ept_time = ept_time.replace(tzinfo=pytz.timezone('US/Eastern')) 
>>> print ept_time 
2014-03-21 07:00:00-05:00 
>>> 
>>> gmt_time = pytz.utc.normalize(ept_time) 
>>> print gmt_time 
2014-03-21 12:00:00+00:00 
>>> 

然而，根據Wolfram Alpha，結果應該是上午11點，而不是12

Answer 1

>>> gmt = pytz.timezone('GMT') 
>>> eastern = pytz.timezone('US/Eastern') 
>>> d = datetime.datetime(2014,03,21,7) 
>>> dateeastern = eastern.localize(d) 
>>> dateeastern 
datetime.datetime(2014, 3, 21, 7, 0, tzinfo=<DstTzInfo 'US/Eastern' EDT-1 day, 20:00:00 DST>) 
>>> dategmt = dateeastern.astimezone(gmt) 
>>> dategmt 
datetime.datetime(2014, 3, 21, 11, 0, tzinfo=<StaticTzInfo 'GMT'>) 

與UTC更換GMT：

>>> eastern = pytz.timezone('US/Eastern') 
>>> d = datetime.datetime(2014,03,21,7) 
>>> dateeastern = eastern.localize(d) 
>>> dateeastern 
datetime.datetime(2014, 3, 21, 7, 0, tzinfo=<DstTzInfo 'US/Eastern' EDT-1 day, 20:00:00 DST>) 
>>> dateutc = dateeastern.astimezone(pytz.utc) 
>>> dateutc 
datetime.datetime(2014, 3, 21, 11, 0, tzinfo=<UTC>) 

編號：How to convert GMT time to EST time using python