Change Utcoffset Of A Timestamp

I know that sometimes when you're converting between timezones Python gets confused about what the result should be, because timezones are hard. from pandas import Timestamp strin

Solution 1:

Before 1901-12-13 20:45:52, the utcoffset was 4 hours and 56 minutes.

You can confirm this using pytz which uses the Olson database. This is the same module that Pandas uses to perform timezone calculations:

importpytzeastern= pytz.timezone('US/Eastern')
for utcdate, info in zip(
        eastern._utc_transition_times, eastern._transition_info):
    utcoffset, dstoffset, tzabbrev = info
    print('{} | {} '.format(utcdate, utcoffset.total_seconds()))

This prints all the utc transition boundaries and utcoffets (in seconds) for the US/Eastern timezone. The first few lines look like this

0001-01-01 00:00:00|-17760.01901-12-13 20:45:52|-18000.01918-03-31 07:00:00|-14400.01918-10-27 06:00:00|-18000.01919-03-30 07:00:00|-14400.0...

So before 1901-12-13 20:45:52, the utcoffset was -17760 seconds (or, equivalently, 4 hours and 56 minutes).

---

The standard way to make a timezone-aware date from a localtime using pytz is to call the localize method:

import datetime as DT
import pytz
eastern = pytz.timezone('US/Eastern')
date = DT.datetime(1900,1,1)
local_date = eastern.localize(date)
print(local_date)

prints

1900-01-01 00:00:00-04:56

This confirms that the Timestamp returned by Pandas is correct:

import pandas as pd
string = "1900-01-01 00:00:00"
ts = pd.Timestamp(string, tz='US/Eastern')
print(ts)
# 1900-01-01 00:00:00-04:56