Is time.mktime the timezone in python?
I am trying to understand the nature of the era and its behavior. Below I have tried the same date with 2 different time points with 1 naive datetime
import time
import pytz
from datetime import datetime, timedelta
pst = pytz.timezone('America/Los_Angeles')
t = datetime(year=2015, month=2, day=2)
t = pst.localize(t)
time.mktime(t.timetuple())
# outputs 1422864000.0
utc = pytz.utc
k = datetime(year=2015, month=2, day=2)
k = utc.localize(k)
time.mktime(k.timetuple())
# outputs 1422864000.0
o = datetime(year=2015, month=2, day=2)
time.mktime(o.timetuple())
# outputs 1422864000.0
They all have the same epoch, but this is surprising since the same date in pst must be offset by 7 hours from utc. Can someone explain this?
thank
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time.mktime()
returns the same result because it gets almost (~ isdst
) the same input in all three cases:
time.struct_time(tm_year=2015, tm_mon=2, tm_mday=2, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=0, tm_yday=33, ..)
.timetuple()
does not store utc offset. This is equivalent to a naive object datetime
.
In general, the "era", i.e. "seconds since epoch" is independent of the time zone. This is not local time or utc. Knowing the timestamp, you can get both with datetime.fromtimestamp
and datetime.utcfromtimestamp
accordingly.
If your timezone is different from 'America/Los_Angeles'
(different utc offset), all three time instances are different and therefore all three POSIX timestamps are different:
#!/usr/bin/env python3
from datetime import datetime
import pytz # $ pip install pytz
pacific = pytz.timezone('America/Los_Angeles')
naive = datetime(2015, 2, 2)
pacific_dt = pacific.localize(naive, is_dst=None)
print(pacific_dt.timestamp())
utc_dt = naive.replace(tzinfo=pytz.utc)
print(utc_dt.timestamp())
print(naive.timestamp()) #NOTE: interpret as local time
The last call can be used mktime(naive.timetuple())
internally.
Output
1422864000.0
1422835200.0
1422831600.0
Note: all three time stamps are different.
To get the POSIX timestamp for older versions of Python see this answer .
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