Python datetime and utc offset conversion ignoring timezone/daylight savings

问题:

I have two operations I want to perform, one the inverse of the other.

1. I have a UNIX timestamp at UTC, say for instance, 1425508527. From this I want to get the year, month, day etc. given a UTC offset. EG. what is the year/month/day/time in (UTC -6 hours)? The answer is March 4, 2015 at 16:35:27. Without providing an offset (or offset zero) the answer should be March 4, 2015 at 22:35:27.

2. Now I have the date at some location, along with the UTC offset. For instance March 4, 2015 at 16:35:27 and the offset (UTC -6 hours). The UNIX UTC timestamp I should get should be 1425508527.

I am able to almost do 2. (using python datetime library) like this:

import datetime.datetime as datetime import time import dateutil.tz as tz  utc_offset = 6 time.mktime(datetime(2015,3,4,16,35,27,                      tzinfo=tz.tzoffset(None, utc_offset*60*60)).utctimetuple()) # => 1425486927 

The problem with the above is that utc_offset has to be given the wrong sign. According to this map, utc_offset should be set to -6. Number 1. I've had no luck with. I don't need/want to deal with timezone information like daylight savings time. How do I implement this in Python?

回答1:

If your system uses Unix time, which does not count leap seconds, then the conversion can be done as follows:

Part 1: timestamp and offset to local date

import datetime as DT import calendar  timestamp = 1425508527 offset = -6  date = DT.datetime(1970,1,1) + DT.timedelta(seconds=timestamp) print(date) # 2015-03-04 22:35:27  localdate = date + DT.timedelta(hours=offset) print(localdate) # 2015-03-04 16:35:27 

Part 2: local date and offset to timestamp

utcdate = localdate - DT.timedelta(hours=offset) assert date == utcdate  timetuple = utcdate.utctimetuple() timestamp2 = calendar.timegm(timetuple) print(timestamp2) # 1425508527 assert timestamp == timestamp2 

文章来源: Python datetime and utc offset conversion ignoring timezone/daylight savings