How to convert UTC to EST with Python and take care of daylight saving automatically?

问题

If I have a bunch of data with date & time in UTC format, how can I convert them to EST.

It can determine when they will be -4(in summer) and -5(in winter) automatically every year? Thanks

回答1:

You'll need to use the pytz module (available from PyPI):

import pytz
from datetime import datetime

est = pytz.timezone('US/Eastern')
utc = pytz.utc
fmt = '%Y-%m-%d %H:%M:%S %Z%z'

winter = datetime(2016, 1, 24, 18, 0, 0, tzinfo=utc)
summer = datetime(2016, 7, 24, 18, 0, 0, tzinfo=utc)

print winter.strftime(fmt)
print summer.strftime(fmt)

print winter.astimezone(est).strftime(fmt)
print summer.astimezone(est).strftime(fmt)

which will print:

2016-01-24 18:00:00 UTC+0000
2016-07-24 18:00:00 UTC+0000
2016-01-24 13:00:00 EST-0500
2016-07-24 14:00:00 EDT-0400

The reason why you'll need to use 'US/Eastern' and not 'EST' is exemplified in the last two lines of output.

回答2:

If you have a pandas series with object datatype, you can first convert it into a DateTime series using pd.to_datetime()

df[col] = pd.to_datetime(your_series, format = '%Y-%m-%d %H:%M:%S', errors ='coerce')

Check if it is timezone aware or not by using series.dt.tz

df[col].dt.tz

If it's not timezone aware, we should make it timezone aware by using series.dt.tz_localize(). Also, do read about the ambiguous and nonexistent parameters of this function

df[col] = your_series[col].dt.tz_localize('UTC')

Now convert this series into the required timezone by series.dt.tz_convert()

df[col] = your_series[col].dt.tz_convert('US/Eastern')

The above method will take care of daylight savings time. If you want to check more timezones you can pip install pytz and

import pytz
pytz.common_timezones

来源：https://stackoverflow.com/questions/48416511/how-to-convert-utc-to-est-with-python-and-take-care-of-daylight-saving-automatic