Converting ISO 8601 date time to seconds in Python

python python-2.7 time iso8601 rfc3339

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Solution 1

If you want to get the seconds since epoch, you can use python-dateutil to convert it to a datetime object and then convert it so seconds using the strftime method. Like so:

>>> import dateutil.parser as dp
>>> t = '1984-06-02T19:05:00.000Z'
>>> parsed_t = dp.parse(t)
>>> t_in_seconds = parsed_t.timestamp()
>>> t_in_seconds
'455051100'

So you were halfway there :)

Solution 2

Your date is UTC time in RFC 3339 format, you could parse it using only stdlib:

from datetime import datetime

utc_dt = datetime.strptime('1984-06-02T19:05:00.000Z', '%Y-%m-%dT%H:%M:%S.%fZ')

# Convert UTC datetime to seconds since the Epoch
timestamp = (utc_dt - datetime(1970, 1, 1)).total_seconds()
# -> 455051100.0

How do I convert it back to ISO 8601 format?

To convert POSIX timestamp back, create a UTC datetime object from it, and format it using .strftime() method:

from datetime import datetime, timedelta

utc_dt = datetime(1970, 1, 1) + timedelta(seconds=timestamp)
print(utc_dt.strftime('%Y-%m-%dT%H:%M:%S.%fZ'))
# -> 1984-06-02T19:05:00.000000Z

Note: It prints six digits after the decimal point (microseconds). To get three digits, see Formatting microseconds to 2 decimal places (in fact converting microseconds into tens of microseconds).

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Zaynaib Giwa

I am a full stack developer who has interests in data journalism and data visualization.If you ever want to do a collaboration just contact me via twitter @AmazingSpeciali or LinkedIn.

Updated on December 20, 2020

Comments

Zaynaib Giwa over 3 years

I am trying to add two times together. The ISO 8601 time stamp is '1984-06-02T19:05:00.000Z', and I would like to convert it to seconds. I tried using the Python module iso8601, but it is only a parser.

Any suggestions?
- Robby Cornelissen over 9 years
  
  What seconds? Seconds since the epoch?
- Zaynaib Giwa over 9 years
  
  I guess so. This is my first time working with dates.
- jfs over 9 years
  
  related: Convert an RFC 3339 time to a standard Python timestamp
Zaynaib Giwa over 9 years

Thanks feynman21. I'm looking at the dateutil.parser documentation. What if I want to convert it back to an ISO format.
chunpoon over 9 years

check this out. datetime.isoformat() should have what you are looking for. So you should first convert the string back to a datetime object using strptime and then call isoformat on that object.
Zaynaib Giwa over 9 years

stackoverflow.com/questions/3401428/… Thank you so much for your help.
Zaynaib Giwa over 9 years

Do you by any chance know how to convert it back to ISO 8601 format? So far anotherTime = datetime.datetime.fromtimestamp(timestamp).isoformat() but it does format .000Z. Any suggestions? I tried multiple things but all I got were errors
jfs over 9 years

@user3426338: I've updated the answer to show how to convert the timestamp (number) back to ISO 8601 format string.
Beni Cherniavsky-Paskin almost 8 years

Impressively short pure stdlib TZ-aware parsing! Alas, it's not ISO 8601 format (see example in question or run date --iso-8601=ns). The ISO standard allows tons of formats so strptime is hopeless, but parsing just ±hh:mm, Z timezone formats (the RFC3339 subset) would be good enough in many cases.
Beni Cherniavsky-Paskin almost 8 years

This only parses Z suffix, doesn't deal with ±hh:mm timezones. %f annoyingly refuses to parse more than 6 fractional digits (rare but legal in both ISO 8601 and RFC 3339) e.g. as printed by date --iso-8601=ns.
jfs almost 8 years

@BeniCherniavsky-Paskin yes, it is correct (moreover %z in Python 3 understands only hhmm utc offset—no colon :). There is no way to parse even rfc 3339 (a profile of rfc 8601) using only stdlib (see the question I've linked above). Though sometimes, parsing Z is all you need as in the example in the question.
jfs over 7 years

parsed_t.strftime('%s') is wrong. parsed_t.tzinfo == tzutc() but .strftime('%s') always uses the local timezone even if it is available (it may and does differ in your case from utc). The correct answer is 455051100, not 455047500 (check datetime.utcfromtimestamp(455051100)).
Blairg23 over 7 years

Such a simple, elegant solution!
Kieleth over 6 years

Adding to @jfs comment: watch out if you're not using UTC timezone in the ISO, since strftime('%s') might bite you painfully: >>> parser.parse('2018-01-10T16:23:47-08:00').strftime('%s') '1515630227' >>> parser.parse('2018-01-10T16:23:47-00:00').strftime('%s') '1515630227'
user1609012 almost 6 years

For Python 3.3 and onward, you can use parsed_t.timestamp() to get the correct time.
k-den about 4 years

What if you'd like the seconds as an integer instead of a string (without an additional conversion.) Is there a way instead of strftime?
jfs over 3 years

@user1609012: beware, if parsed_t is not time zone aware then timestamp() may produce incorrect result: it interprets naive datetime as local time that may differ from the desired time zone such as UTC.
Pavneet Singh over 3 years

The above solution does not actually check the Z value to convert to GMT. If you paste the above t_in_seconds returned in the results to an epoch converter it returns Saturday, 2 June 1984 18:05:00 in GMT. so it's either not timezone aware or does not consider daylight savings.
Ian Smith over 2 years

Seems overly complicated --> (int(ts[-2:])*60 + 60 * 60 * int(ts[-4:-2]) * int(ts[-5:-4]+'1')