get UTC timestamp in python with datetime

Question

Is there a way to get the UTC timestamp by specifying the date  What I would expect   datetime 2008  1  1  0  0  0  0    should result in   1199145600   Creating a naive datetime object means that there is no time zone information  If I look at the documentation for datetime utcfromtimestamp  creating a UTC timestamp means leaving out the time zone information  So I would guess  that creating a naive datetime object  like I did  would result in a UTC timestamp  However   then   datetime 2008  1  1  0  0  0  0  datetime utcfromtimestamp float then strftime   s       results in  2007-12-31 23 00 00   Is there still any hidden time zone information in the datetime object  What am I doing wrong

User · Answer

There is indeed a problem with using utcfromtimestamp and specifying time zones. A nice example/explanation is available on the following question:

How to specify time zone (UTC) when converting to Unix time? (Python)

User · Answer

Simplest way     gt  gt  gt  from datetime import datetime  gt  gt  gt  dt   datetime 2008  1  1  0  0  0  0   gt  gt  gt  dt strftime   s    1199163600      Edit   Daniel is correct  this would convert it to the machine s timezone  Here is a revised answer    gt  gt  gt  from datetime import datetime  timezone  gt  gt  gt  epoch   datetime 1970  1  1  0  0  0  0  timezone utc   gt  gt  gt  dt   datetime 2008  1  1  0  0  0  0  timezone utc   gt  gt  gt  int  dt-epoch  total seconds     1199145600    In fact  its not even necessary to specify timezone utc  because the time difference is the same so long as both datetime have the same timezone  or no timezone     gt  gt  gt  from datetime import datetime  gt  gt  gt  epoch   datetime 1970  1  1  0  0  0  0   gt  gt  gt  dt   datetime 2008  1  1  0  0  0  0   gt  gt  gt  int  dt-epoch  total seconds    1199145600

User · Answer

Another possibility is   d   datetime datetime utcnow   epoch   datetime datetime 1970 1 1  t    d - epoch  total seconds     This works as both  d  and  epoch  are naive datetimes  making the  -  operator valid  and returning an interval  total seconds   turns the interval into seconds  Note that total seconds   returns a float  even d microsecond    0

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Also note the calendar timegm   function as described by this blog entry   import calendar calendar timegm utc timetuple    The output should agree with the solution of vaab

User · Answer

If input datetime object is in UTC    gt  gt  gt  dt   datetime 2008  1  1  0  0  0  0   gt  gt  gt  timestamp    dt - datetime 1970  1  1   total seconds   1199145600 0   Note  it returns float i e   microseconds are represented as fractions of a second   If input date object is in UTC    gt  gt  gt  from datetime import date  gt  gt  gt  utc date   date 2008  1  1   gt  gt  gt  timestamp    utc date toordinal   - date 1970  1  1  toordinal      24 60 60 1199145600   See more details at Converting datetime date to UTC timestamp in Python

User · Answer

I think the correct way to phrase your question is Is there a way to get the timestamp by specifying the date in UTC   because timestamp is just a number which is absolute  not relative  The relative  or timezone aware  piece is the date   I find pandas very convenient for timestamps  so   import pandas as pd dt1   datetime 2008  1  1  0  0  0  0  ts1   pd Timestamp dt1  tz  utc   timestamp     make sure you get back dt1 datetime utcfromtimestamp ts1

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Na  ve datetime versus aware datetime  Default datetime objects are said to be  na  ve   they keep time information without the time zone information  Think about na  ve datetime as a relative number  ie   4  without a clear origin  in fact your origin will be common throughout your system boundary     In contrast  think about aware datetime as absolute numbers  ie  8  with a common origin for the whole world   Without timezone information you cannot convert the  naive  datetime towards any non-naive time representation  where does  4 targets if we don t know from where to start     This is why you can t have a datetime datetime toutctimestamp   method   cf  http   bugs python org issue1457227   To check if your datetime dt is na  ve  check dt tzinfo  if None  then it s na  ve   datetime now             DANGER  returns na  ve datetime pointing on local time datetime 1970  1  1      returns na  ve datetime pointing on user given time   I have na  ve datetimes  what can I do    You must make an assumption depending on your particular context  The question you must ask yourself is  was your datetime on UTC   or was it local time     If you were using UTC  you are out of trouble    import calendar  def dt2ts dt          Converts a datetime object to UTC timestamp      naive datetime will be considered UTC                return calendar timegm dt utctimetuple     If you were NOT using UTC  welcome to hell   You have to make your datetime non-na  ve prior to using the former function  by giving them back their intended timezone   You ll need the name of the timezone and the information about if DST was in effect when producing the target na  ve datetime  the last info about DST is required for cornercases    import pytz        pip install pytz  mytz   pytz timezone  Europe Amsterdam                  Set your timezone  dt   mytz normalize mytz localize dt  is dst True       Set is dst accordingly   Consequences of not providing is dst   Not using is dst will generate incorrect time  and UTC timestamp  if target datetime was produced while a backward DST was put in place  for instance changing DST time by removing one hour    Providing incorrect is dst will of course generate incorrect time  and UTC timestamp  only on DST overlap or holes  And  when  providing  also incorrect time  occuring in  holes   time that never existed due to forward shifting DST   is dst will give an interpretation of  how to consider this bogus time  and this is the only case where   normalize     will actually do something here  as it ll then  translate it as an actual valid time  changing the datetime AND the  DST object if required   Note that  normalize   is not required  for having a correct UTC timestamp at the end  but is probably  recommended if you dislike the idea of having bogus times in your  variables  especially if you re-use this variable elsewhere   and AVOID USING THE FOLLOWING   cf  Datetime Timezone conversion using pytz   dt   dt replace tzinfo timezone  Europe Amsterdam        BAD      Why  because  replace   replaces blindly the tzinfo without  taking into account the target time and will choose a bad DST object   Whereas  localize   uses the target time and your is dst hint to select the right DST object    OLD incorrect answer  thanks  J F Sebastien for bringing this up    Hopefully  it is quite easy to guess the timezone  your local origin  when you create your naive datetime object as it is related to the system configuration that you would hopefully NOT change between the naive datetime object creation and the moment when you want to get the UTC timestamp  This trick can be used to give an imperfect question   By using time mktime we can create an utc mktime   def utc mktime utc tuple          Returns number of seconds elapsed since epoch      Note that no timezone are taken into consideration       utc tuple must be   year  month  day  hour  minute  second                if len utc tuple     6          utc tuple     0  0  0      return time mktime utc tuple  - time mktime  1970  1  1  0  0  0  0  0  0    def datetime to timestamp dt          Converts a datetime object to UTC timestamp         return int utc mktime dt timetuple       You must make sure that your datetime object is created on the same timezone than the one that has created your datetime   This last solution is incorrect because it makes the assumption that the UTC offset from now is the same than the UTC offset from EPOCH  Which is not the case for a lot of timezones  in specific moment of the year for the Daylight Saving Time  DST  offsets

User · Answer

A simple solution without using external modules   from datetime import datetime  timezone  dt   datetime 2008  1  1  0  0  0  0  int dt replace tzinfo timezone utc  timestamp

User · Answer

The accepted answer seems not work for me  My solution   import time utc 0   int time mktime datetime 1970  01  01  timetuple     def datetime2ts dt          Converts a datetime object to UTC timestamp        return int time mktime dt utctimetuple     - utc 0

User · Answer

I feel like the main answer is still not so clear  and it s worth taking the time to understand time and timezones   The most important thing to understand when dealing with time is that time is relative    2017-08-30 13 23 00   a naive datetime   represents a local time somewhere in the world  but note that 2017-08-30 13 23 00 in London is NOT THE SAME TIME as 2017-08-30 13 23 00 in San Francisco    Because the same time string can be interpreted as different points-in-time depending on where you are in the world  there is a need for an absolute notion of time   A UTC timestamp is a number in seconds  or milliseconds  from Epoch  defined as 1 January 1970 00 00 00 at GMT timezone  00 00 offset     Epoch is anchored on the GMT timezone and therefore is an absolute point in time  A UTC timestamp being an offset from an absolute time therefore defines an absolute point in time    This makes it possible to order events in time   Without timezone information  time is relative  and cannot be converted to an absolute notion of time without providing some indication of what timezone the naive datetime should be anchored to   What are the types of time used in computer system    naive datetime  usually for display  in local time  i e  in the browser  where the OS can provide timezone information to the program   UTC timestamps  A UTC timestamp is an absolute point in time  as mentioned above  but it is anchored in a given timezone  so a UTC timestamp can be converted to a datetime in any timezone  however it does not contain timezone information  What does that mean  That means that 1504119325 corresponds to 2017-08-30T18 55 24Z  or 2017-08-30T17 55 24-0100 or also 2017-08-30T10 55 24-0800  It doesn t tell you where the datetime recorded is from  It s usually used on the server side to record events  logs  etc     or used to convert a timezone aware datetime to an absolute point in time and compute time differences  ISO-8601 datetime string  The ISO-8601 is a standardized format to record datetime with timezone   It s in fact several formats  read on here  https   en wikipedia org wiki ISO 8601  It is used to communicate timezone aware datetime information in a serializable manner between systems    When to use which  or rather when do you need to care about timezones     If you need in any way to care about time-of-day  you need timezone information  A calendar or alarm needs time-of-day to set a meeting at the correct time of the day for any user in the world  If this data is saved on a server  the server needs to know what timezone the datetime corresponds to  To compute time differences between events coming from different places in the world  UTC timestamp is enough  but you lose the ability to analyze at what time of day events occured  ie  for web analytics  you may want to know when users come to your site in their local time  do you see more users in the morning or the evening  You can t figure that out without time of day information    Timezone offset in a date string   Another point that is important  is that timezone offset in a date string is not fixed  That means that because 2017-08-30T10 55 24-0800 says the offset -0800 or 8 hours back  doesn t mean that it will always be    In the summer it may well be in daylight saving time  and it would be -0700  What that means is that timezone offset   0100  is not the same as timezone name  Europe France  or even timezone designation  CET   America Los Angeles timezone is a place in the world  but it turns into PST  Pacific Standard Time  timezone offset notation in the winter  and PDT  Pacific Daylight Time  in the summer   So  on top of getting the timezone offset from the datestring  you should also get the timezone name to be accurate   Most packages will be able to convert numeric offsets from daylight saving time to standard time on their own  but that is not necessarily trivial with just offset  For example WAT timezone designation in West Africa  is UTC 0100 just like CET timezone in France  but France observes daylight saving time  while West Africa does not  because they re close to the equator   So  in short  it s complicated  VERY complicated  and that s why you should not do this yourself  but trust a package that does it for you  and KEEP IT UP TO DATE

[python] get UTC timestamp in python with datetime

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