Convert datetime to Unix timestamp and convert it back in python

Question

I have dt   datetime 2013 9 1 11   and I would like to get a Unix timestamp of this datetime object   When I do  dt - datetime 1970 1 1   total seconds   I got the timestamp 1378033200   When converting it back using datetime fromtimestamp I got datetime datetime 2013  9  1  6  0    The hour doesn t match  What did I miss here

User · Accepted Answer

What you missed here is timezones   Presumably you ve five hours off UTC  so 2013-09-01T11 00 00 local and 2013-09-01T06 00 00Z are the same time   You need to read the top of the datetime docs  which explain about timezones and  naive  and  aware  objects   If your original naive datetime was UTC  the way to recover it is to use utcfromtimestamp instead of fromtimestamp   On the other hand  if your original naive datetime was local  you shouldn t have subtracted a UTC timestamp from it in the first place  use datetime fromtimestamp 0  instead   Or  if you had an aware datetime object  you need to either use a local  aware  epoch on both sides  or explicitly convert to and from UTC   If you have  or can upgrade to  Python 3 3 or later  you can avoid all of these problems by just using the timestamp method instead of trying to figure out how to do it yourself  And even if you don t  you may want to consider borrowing its source code    And if you can wait for Python 3 4  it looks like PEP 341 is likely to make it into the final release  which means all of the stuff J F  Sebastian and I were talking about in the comments should be doable with just the stdlib  and working the same way on both Unix and Windows

User · Answer

If you want to convert a python datetime to seconds since epoch you should do it explicitly   gt  gt  gt  import datetime  gt  gt  gt  datetime datetime 2012  04  01  0  0  strftime   s    1333234800   gt  gt  gt   datetime datetime 2012  04  01  0  0  - datetime datetime 1970  1  1   total seconds   1333238400 0  In Python 3 3  you can use timestamp   instead   gt  gt  gt  import datetime  gt  gt  gt  datetime datetime 2012  4  1  0  0  timestamp   1333234800 0

User · Answer

Well  when converting TO unix timestamp  python is basically assuming UTC  but while converting back it will give you a date converted to your local timezone   See this question answer  Get timezone used by datetime datetime fromtimestamp

User · Answer

def datetime to epoch d1          create 1 1 1970 in same timezone as d1     d2   datetime 1970  1  1  tzinfo d1 tzinfo      time delta   d1 - d2     ts   int time delta total seconds        return ts   def epoch to datetime string ts  tz name  UTC        x timezone   timezone tz name      d1   datetime fromtimestamp ts  x timezone      x   d1 strftime   d  B  Y  H  M  S       return x

User · Answer

For working with UTC timezones   time stamp   calendar timegm dt timetuple     datetime utcfromtimestamp time stamp

User · Answer

def dt2ts dt  utc False       if utc          return calendar timegm dt timetuple        if dt tzinfo is None          return int time mktime dt timetuple         utc dt   dt astimezone tz tzutc    timetuple       return calendar timegm utc dt    If you want UTC timestamp  time mktime just for local dt  Use calendar timegm is safe but dt must the utc zone so change the zone to utc  If dt in UTC just use calendar timegm

User · Answer

If your datetime object represents UTC time  don t use time mktime  as it assumes the tuple is in your local timezone  Instead  use calendar timegm    gt  gt  gt  import datetime  calendar  gt  gt  gt  d   datetime datetime 1970  1  1  0  1  0   gt  gt  gt  calendar timegm d timetuple    60

User · Answer

solution is   import time import datetime d   datetime date 2015 1 5   unixtime   time mktime d timetuple

User · Answer

You ve missed the time zone info  already answered  agreed   arrow package allows to avoid this torture with datetimes  It is already written  tested  pypi-published  cross-python  2 6     3 xx     All you need  pip install arrow  or add to dependencies   Solution for your case  dt   datetime 2013 9 1 11  arrow get dt  timestamp    gt  gt  gt  1378033200  bc   arrow get 1378033200  datetime print bc     gt  gt  gt  datetime datetime 2013  9  1  11  0  tzinfo tzutc    print bc isoformat       gt  gt  gt   2013-09-01T11 00 00 00 00

User · Answer

Rather than this expression to create a POSIX timestamp from dt    dt - datetime 1970 1 1   total seconds     Use this   int dt strftime   s      I get the right answer in your example using the second method   EDIT  Some followup    After some comments  see below   I was curious about the lack of support or documentation for  s in strftime  Here s what I found   In the Python source for datetime and time  the string STRFTIME FORMAT CODES tells us    Other codes may be available on your platform   See documentation for the C library strftime function     So now if we man strftime  on BSD systems such as Mac OS X   you ll find support for  s     s is replaced by the number of seconds since the Epoch  UTC  see mktime 3       Anyways  that s why  s works on the systems it does   But there are better solutions to OP s problem  that take timezones into account    See  abarnert s accepted answer here

User · Answer

This class will cover your needs  you can pass the variable into ConvertUnixToDatetime  amp  call which function you want it to operate based off   from datetime import datetime import time  class ConvertUnixToDatetime      def   init   self  date           self date   date        Convert unix to date object     def convert unix self           unix   self date            Check if unix is a string or int  amp  proceeds with correct conversion         if type unix    name       str               unix   int unix 0 10           else              unix   int str unix  0 10            date   datetime utcfromtimestamp unix  strftime   Y- m- d  H  M  S            return date        Convert date to unix object     def convert date self           date   self date            Check if datetime object or raise ValueError         if type date    name       datetime               unixtime   int time mktime date timetuple             else              raise ValueError  You are trying to pass a None Datetime object           return type unixtime    name    unixtime   if   name         main            Test Date     date test   ConvertUnixToDatetime datetime today        date test   date test convert date       print date test         Test Unix     unix test   ConvertUnixToDatetime date test 1       print unix test convert unix

[python] Convert datetime to Unix timestamp and convert it back in python

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