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Date: Tue, 24 Mar 2015 15:34:25 -0700
From: Gary Herron <gherron@digipen.edu>
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Subject: Re: Daylight savings time question
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On 03/24/2015 03:24 PM, Dan Stromberg wrote:
> Is there a way of "adding" 4 hours and getting a jump of 5 hours on
> March 8th, 2015 (due to Daylight Savings Time), without hardcoding
> when to spring forward and when to fall back?  I'd love it if there's
> some library that'll do this for me.
>
> #!/usr/bin/python
>
> import pytz
> import datetime
>
> def main():
>      # On 2015-03-08, 2:00 AM to 2:59AM Pacific time does not exist -
> the clock jumps forward an hour.
>      weird_naive_datetime = datetime.datetime(2015, 3, 8, 1, 0,
> 0).replace(tzinfo=pytz.timezone('US/Pacific'))
>      weird_tz_aware_datetime =
> weird_naive_datetime.replace(tzinfo=pytz.timezone('US/Pacific'))
>      print(weird_tz_aware_datetime)
>      four_hours=datetime.timedelta(hours=4)
>      print('Four hours later is:')
>      print(weird_tz_aware_datetime + four_hours)
>      print('...but I want numerically 5 hours later, because of
> Daylight Savings Time')
>
> main()
>
>
> Thanks!

The pyzt module (which you've imported) has lots to say about this. Look 
at its procedures "localize' and 'normalize' and all the rest of the 
pyzt documentation.



-- 
Dr. Gary Herron
Department of Computer Science
DigiPen Institute of Technology
(425) 895-4418