如何将python时间戳字符串转换为纪元？

Question

I have the following string:

mytime = "2009-03-08T00:27:31.807Z"

How do I convert it to epoch in python?

I tried:

import time
p = '%Y-%m-%dT%H:%M:%S'
int(time.mktime(time.strptime(s, p)))

But it does not work with the 31.807Z .

Answer 1

There are two parts:

1. Convert the time string into a broken-down time. See How to parse ISO formatted date in python?
2. Convert the UTC time to "seconds since the Epoch" (POSIX timestamp) .

#!/usr/bin/env python
from datetime import datetime

utc_time = datetime.strptime("2009-03-08T00:27:31.807Z", "%Y-%m-%dT%H:%M:%S.%fZ")
epoch_time = (utc_time - datetime(1970, 1, 1)).total_seconds()
# -> 1236472051.807

If you are sure that you want to ignore fractions of a second and to get an integer result:

#!/usr/bin/env python
import time
from calendar import timegm

utc_time = time.strptime("2009-03-08T00:27:31.807Z", "%Y-%m-%dT%H:%M:%S.%fZ")
epoch_time = timegm(utc_time)
# -> 1236472051

To support timestamps that correspond to a leap second such as Wed July 1 2:59:60 MSK 2015 , you could use a combination of time.strptime() and datetime (if you care about leap seconds you should take into account the microseconds too) .

Answer 2

You are missing .%fZ from your format string.

p = '%Y-%m-%dT%H:%M:%S.%fZ'

The correct way to convert to epoch is to use datetime :

from datetime import datetime

p = '%Y-%m-%dT%H:%M:%S.%fZ'
mytime = "2009-03-08T00:27:31.807Z"
epoch = datetime(1970, 1, 1)
print((datetime.strptime(mytime, p) - epoch).total_seconds())

Or call int if you want to ignore fractions.

Answer 3

dateutil is the only library i have found that correctly deals with the timezone offset identitifier ( Z )

pip install python-dateutil

then

from dateutil.parser import parse as date_parse
print date_parse("2009-03-08T00:27:31.807Z")
#get timestamp

import calendar
dt =  date_parse("2009-03-08T00:27:31.807Z")
timestamp1 = calendar.timegm(dt.timetuple())

Answer 4

Code:

import datetime
epoch = datetime.datetime(1970, 1, 1)

mytime = "2009-03-08T00:27:31.807Z"
myformat = "%Y-%m-%dT%H:%M:%S.%fZ"
mydt = datetime.datetime.strptime(mytime, myformat)
val = (mydt - epoch).total_seconds()

print(val)
> 1236472051.81
repr(val)
> '1236472051.807'

Notes:

• When using time.strptime() , the returned time.struct_time does not support sub-second precision.
• The %f format is for microseconds. When parsing it need not be the full 6 digits.

Answer 5

dateutil has recently been added back to python packages, it's an easy one liner that handles formatting on its own.

from dateutil import parser
strtime = '2009-03-08T00:27:31.807Z'
epoch = parser.parse(strtime).timestamp()

Answer 6

Python 3.7+ The string format in question can be parsed by strptime :

from datetime import datetime
datetime.strptime("2009-03-08T00:27:31.807Z", '%Y-%m-%dT%H:%M:%S.%f%z')
>>> datetime.datetime(2009, 3, 8, 0, 27, 31, 807000, tzinfo=datetime.timezone.utc)

Another option using the built-in datetime.fromisoformat() : As mentioned in this thread linked by @jfs, fromisoformat() doesn't parse the 'Z' character to UTC although this is part of the RFC3339 definitions. A little work-around can make it work - some will consider this nasty but it's efficient after all.

from datetime import datetime
mytime = "2009-03-08T00:27:31.807Z"
datetime.fromisoformat(mytime.replace("Z", "+00:00")).timestamp()
>>> 1236472051.807

Answer 7

This code works in Python 3.6 to convert a datetime string to epoch in UTC or local timezone.

from datetime import datetime, timedelta
from dateutil.tz import tzutc, tzlocal

mydate = '2020-09-25'
mytime = '06:00:00'

epoch1970 = datetime(1970, 1, 1, 0, 0, 0, tzinfo=tzutc())

myepochutc = int((datetime.strptime(mydate + ' ' + mytime, "%Y-%m-%d %H:%M:%S").replace(tzinfo=tzutc()) - epoch1970).total_seconds()*1000)

myepochlocal = int((datetime.strptime(mydate + ' ' + mytime, "%Y-%m-%d %H:%M:%S").replace(tzinfo=tzlocal()) - epoch1970).total_seconds()*1000)

#epoch will be in milliseconds
print(myepochutc)   #if mydate/mytime was in utc
print(myepochlocal) #if mydate/mytime was in local timezone