python – datetime with timezone to epoch

To convert a datetime with timezone to epoch (POSIX timestamp):

from datetime import datetime
import pytz

tz = pytz.timezone('CST6CDT')

# a datetime with timezone
dt_with_tz = tz.localize(datetime(2012, 8, 28, 19, 33, 50), is_dst=None)

# get timestamp
ts = (dt_with_tz - datetime(1970, 1, 1, tzinfo=pytz.utc)).total_seconds()
# -> 1346200430.0

It is how datetime.timestamp method is implemented for timezone-aware datetime objects in Python 3.

To get “now epoch”:

from datetime import datetime

now_epoch = (datetime.utcnow() - datetime(1970, 1, 1)).total_seconds()

Or (assuming time uses POSIX epoch):

import time

now_epoch = time.time()

Getting “beginning of current day epoch” is more complex because current day may be different in different timezones:

from datetime import datetime, time
import pytz

tz = pytz.timezone('CST6CDT')

# get current date in given timezone
today = datetime.now(tz).date()
# -> datetime.date(2013, 6, 22)

# get beginning of current day in given timezone as a datetime with timezone
midnight = tz.localize(datetime.combine(today, time(0, 0)), is_dst=None)
# -> datetime.datetime(2013, 6, 22, 0, 0, tzinfo=<DstTzInfo 'CST6CDT'...>)

# get timestamp
ts = (midnight - datetime(1970, 1, 1, tzinfo=pytz.utc)).total_seconds()
# -> 1371877200.0 

See How do I get the UTC time of “midnight” for a given timezone?.

To get “beginning of current day epoch” assuming UTC date:

from datetime import datetime, date

# get current date in UTC
utc_date = datetime.utcnow().date()
# -> datetime.date(2013, 6, 23)

# get timestamp
ts = (utc_date - date(1970, 1, 1)).days * 86400
# -> 1371945600

See Converting datetime.date/datetime.datetime to UTC timestamp in Python.

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