I have a file. In Python, I would like to take its creation time, and convert it to an ISO time (ISO 8601) string while preserving the fact that it was created in the Eastern Time Zone (ET).
How do I take the file's ctime and convert it to an ISO time string that indicates the Eastern Time Zone (and takes into account daylight savings time, if necessary)?
Local to ISO 8601:
import datetime
datetime.datetime.now().isoformat()
>>> 2020-03-20T14:28:23.382748
UTC to ISO 8601:
import datetime
datetime.datetime.utcnow().isoformat()
>>> 2020-03-20T01:30:08.180856
Local to ISO 8601 without microsecond:
import datetime
datetime.datetime.now().replace(microsecond=0).isoformat()
>>> 2020-03-20T14:30:43
UTC to ISO 8601 with TimeZone information (Python 3):
import datetime
datetime.datetime.utcnow().replace(tzinfo=datetime.timezone.utc).isoformat()
>>> 2020-03-20T01:31:12.467113+00:00
UTC to ISO 8601 with Local TimeZone information without microsecond (Python 3):
import datetime
datetime.datetime.now().astimezone().replace(microsecond=0).isoformat()
>>> 2020-03-20T14:31:43+13:00
Local to ISO 8601 with TimeZone information (Python 3):
import datetime
datetime.datetime.now().astimezone().isoformat()
>>> 2020-03-20T14:32:16.458361+13:00
Notice there is a bug when using astimezone() on utc time. This gives an incorrect result:
datetime.datetime.utcnow().astimezone().isoformat() #Incorrect result
For Python 2, see and use pytz.
ISO 8601 allows a compact representation with no separators except for the T, so I like to use this one-liner to get a quick timestamp string:
>>> datetime.datetime.utcnow().strftime("%Y%m%dT%H%M%S.%fZ")
'20180905T140903.591680Z'
If you don't need the microseconds, just leave out the .%f part:
>>> datetime.datetime.utcnow().strftime("%Y%m%dT%H%M%SZ")
'20180905T140903Z'
For local time:
>>> datetime.datetime.now().strftime("%Y%m%dT%H%M%S")
'20180905T140903'
In general, I recommend you leave the punctuation in. RFC 3339 recommends that style because if everyone uses punctuation, there isn't a risk of things like multiple ISO 8601 strings being sorted in groups on their punctuation. So the one liner for a compliant string would be:
>>> datetime.datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ")
'2018-09-05T14:09:03Z'
Here is what I use to convert to the XSD datetime format:
from datetime import datetime
datetime.now().replace(microsecond=0).isoformat()
# You get your ISO string
I came across this question when looking for the XSD date time format (xs:dateTime). I needed to remove the microseconds from isoformat.
ISO 8601 Time Representation
The international standard ISO 8601 describes a string representation for dates and times. Two simple examples of this format are
2010-12-16 17:22:15
20101216T172215
(which both stand for the 16th of December 2010), but the format also allows for sub-second resolution times and to specify time zones. This format is of course not Python-specific, but it is good for storing dates and times in a portable format. Details about this format can be found in the Markus Kuhn entry.
I recommend use of this format to store times in files.
One way to get the current time in this representation is to use strftime from the time module in the Python standard library:
>>> from time import strftime
>>> strftime("%Y-%m-%d %H:%M:%S")
'2010-03-03 21:16:45'
You can use the strptime constructor of the datetime class:
>>> from datetime import datetime
>>> datetime.strptime("2010-06-04 21:08:12", "%Y-%m-%d %H:%M:%S")
datetime.datetime(2010, 6, 4, 21, 8, 12)
The most robust is the Egenix mxDateTime module:
>>> from mx.DateTime.ISO import ParseDateTimeUTC
>>> from datetime import datetime
>>> x = ParseDateTimeUTC("2010-06-04 21:08:12")
>>> datetime.fromtimestamp(x)
datetime.datetime(2010, 3, 6, 21, 8, 12)
References
The Python time module documentation
The Python datetime class documentation
The Egenix mxDateTime class
I found the datetime.isoformat in the documentation. It seems to do what you want:
datetime.isoformat([sep])
Return a string representing the date and time in ISO 8601 format, YYYY-MM-DDTHH:MM:SS.mmmmmm or, if microsecond is 0, YYYY-MM-DDTHH:MM:SS
If utcoffset() does not return None, a 6-character string is appended, giving the UTC offset in (signed) hours and minutes: YYYY-MM-DDTHH:MM:SS.mmmmmm+HH:MM or, if microsecond is 0 YYYY-MM-DDTHH:MM:SS+HH:MM
The optional argument sep (default 'T') is a one-character separator, placed between the date and time portions of the result. For example,
>>>
>>> from datetime import tzinfo, timedelta, datetime
>>> class TZ(tzinfo):
... def utcoffset(self, dt): return timedelta(minutes=-399)
...
>>> datetime(2002, 12, 25, tzinfo=TZ()).isoformat(' ')
'2002-12-25 00:00:00-06:39'
For those who are looking for a date-only solution, it is:
import datetime
datetime.date.today().isoformat()
The ISO 8601 time format does not store a time zone name, only the corresponding UTC offset is preserved.
To convert a file ctime to an ISO 8601 time string while preserving the UTC offset in Python 3:
>>> import os
>>> from datetime import datetime, timezone
>>> ts = os.path.getctime(some_file)
>>> dt = datetime.fromtimestamp(ts, timezone.utc)
>>> dt.astimezone().isoformat()
'2015-11-27T00:29:06.839600-05:00'
The code assumes that your local timezone is Eastern Time Zone (ET) and that your system provides a correct UTC offset for the given POSIX timestamp (ts), i.e., Python has access to a historical timezone database on your system or the time zone had the same rules at a given date.
If you need a portable solution; use the pytz module that provides access to the tz database:
>>> import os
>>> from datetime import datetime
>>> import pytz # pip install pytz
>>> ts = os.path.getctime(some_file)
>>> dt = datetime.fromtimestamp(ts, pytz.timezone('America/New_York'))
>>> dt.isoformat()
'2015-11-27T00:29:06.839600-05:00'
The result is the same in this case.
If you need the time zone name/abbreviation/zone id, store it separately.
>>> dt.astimezone().strftime('%Y-%m-%d %H:%M:%S%z (%Z)')
'2015-11-27 00:29:06-0500 (EST)'
Note: no, : in the UTC offset and EST timezone abbreviation is not part of the ISO 8601 time format. It is not unique.
Different libraries/different versions of the same library may use different time zone rules for the same date/timezone. If it is a future date then the rules might be unknown yet. In other words, the same UTC time may correspond to a different local time depending on what rules you use -- saving a time in ISO 8601 format preserves UTC time and the local time that corresponds to the current time zone rules in use on your platform. You might need to recalculate the local time on a different platform if it has different rules.
You'll need to use os.stat to get the file creation time and a combination of time.strftime and time.timezone for formatting:
>>> import time
>>> import os
>>> t = os.stat('C:/Path/To/File.txt').st_ctime
>>> t = time.localtime(t)
>>> formatted = time.strftime('%Y-%m-%d %H:%M:%S', t)
>>> tz = str.format('{0:+06.2f}', float(time.timezone) / 3600)
>>> final = formatted + tz
>>>
>>> final
'2008-11-24 14:46:08-02.00'
Just make the life simple please:
Use UTC time
Microsecond
one line code
f"{datetime.datetime.utcnow().isoformat()[:-3]}Z"
output:
2022-02-25T02:08:40.684Z
Standard RFC-3339 in milliseconds
I needed the time in this format for a LoRa application so I came up with this, I hope it helps:
from datetime import datetime
from time import strftime
# Get the current time in the format: 2021-03-20T16:51:23.644+01:00
def rfc3339_time_ms():
datetime_now = datetime.utcnow()
# Remove the microseconds
datetime_now_ms = datetime_now.strftime("%Y-%m-%dT%H:%M:%S.%f")[:-3]
# Add the timezone as "+/-HHMM", and the colon in "+/-HH:MM"
datetime_now_ms_tz = datetime_now_ms + strftime("%z")
rfc3339_ms_now = datetime_now_ms_tz[:-2] + ":" + datetime_now_ms_tz[-2:]
# print(f"Current time in ms in RFC-3339 format: {rfc3339_ms_now}")
return rfc3339_ms_now
Correct me if I'm wrong (I'm not), but the offset from UTC changes with daylight saving time. So you should use
tz = str.format('{0:+06.2f}', float(time.altzone) / 3600)
I also believe that the sign should be different:
tz = str.format('{0:+06.2f}', -float(time.altzone) / 3600)
I could be wrong, but I don't think so.
Adding a small variation to estani's excellent answer
Local to ISO 8601 with TimeZone and no microsecond info (Python 3):
import datetime, time
utc_offset_sec = time.altzone if time.localtime().tm_isdst else time.timezone
utc_offset = datetime.timedelta(seconds=-utc_offset_sec)
datetime.datetime.now().replace(microsecond=0, tzinfo=datetime.timezone(offset=utc_offset)).isoformat()
Sample Output:
'2019-11-06T12:12:06-08:00'
Tested that this output can be parsed by both Javascript Date and C# DateTime/DateTimeOffset
I agree with Jarek, and I furthermore note that the ISO offset separator character is a colon, so I think the final answer should be:
isodate.datetime_isoformat(datetime.datetime.now()) + str.format('{0:+06.2f}', -float(time.timezone) / 3600).replace('.', ':')
I've developed this function:
def iso_8601_format(dt):
"""YYYY-MM-DDThh:mm:ssTZD (1997-07-16T19:20:30-03:00)"""
if dt is None:
return ""
fmt_datetime = dt.strftime('%Y-%m-%dT%H:%M:%S')
tz = dt.utcoffset()
if tz is None:
fmt_timezone = "+00:00"
else:
fmt_timezone = str.format('{0:+06.2f}', float(tz.total_seconds() / 3600))
return fmt_datetime + fmt_timezone
import datetime, time
def convert_enddate_to_seconds(self, ts):
"""Takes ISO 8601 format(string) and converts into epoch time."""
dt = datetime.datetime.strptime(ts[:-7],'%Y-%m-%dT%H:%M:%S.%f')+\
datetime.timedelta(hours=int(ts[-5:-3]),
minutes=int(ts[-2:]))*int(ts[-6:-5]+'1')
seconds = time.mktime(dt.timetuple()) + dt.microsecond/1000000.0
return seconds
>>> import datetime, time
>>> ts = '2012-09-30T15:31:50.262-08:00'
>>> dt = datetime.datetime.strptime(ts[:-7],'%Y-%m-%dT%H:%M:%S.%f')+ datetime.timedelta(hours=int(ts[-5:-3]), minutes=int(ts[-2:]))*int(ts[-6:-5]+'1')
>>> seconds = time.mktime(dt.timetuple()) + dt.microsecond/1000000.0
>>> seconds
1348990310.26
I have a string in the form of 68.830320 Format. this I need to convert to time Format in second.millisecond. it does not contain date or any other values. I cannot use strptime since the Format is not right. tstamp that I'm trying to parse is a list of calues containg values with decimal Point. I cannot round this value. it still gives error. I'm not sure how to proceeed. please help!
tried a lot of threads from here that always take the datetime object. But since my Format is not in the same way, I cannot use that info. I have tries .time dateutil, and everything else available. I still cannot solve this problem
tstamp = child2.get('timestamp').replace(" ", "").replace("\n", "")
print(tstamp)
parser.parser(tstamp)
format_time = datetime.date(tstamp)
print(format_time)
A number of seconds isn't a datetime, it's a timedelta. It isn't a datetime because you can't take the string "68.830320" and set the hands on a wall clock to represent that time.
Convert your string to a timedelta like this:
>>> from datetime import timedelta
>>> mytime = timedelta(seconds=float("68.830320"))
>>> mytime
datetime.timedelta(0, 68, 830320)
You can then add the timedelta to a datetime to get a wall clock time.
I have a datetime object with integer number of seconds (ex: 2010-04-16 16:51:23). I am using the following command to extract exact time
dt = datetime.datetime.strptime(time, '%Y-%m-%d %H:%M:%S.%f
(generically, I have decimals (ex: 2010-04-16 16:51:23.1456) but sometimes I don't. So when I run this command, I get an error message
ValueError: time data '2010-04-16 16:51:23' does not match format '%Y-%m-%d %H:%M:%S.%f'
How do I go about resolving this?
It's because you don't have the format you specified. You have the format:
'%Y-%m-%d %H:%M:%S'
There are multiple solutions. First, always generate the data in the same format (adding .00 if you need to).
A second solution is that you try to decode in one format and if you fail, you decode using the other format:
try:
dt = datetime.datetime.strptime(time, '%Y-%m-%d %H:%M:%S.%f')
except ValueError:
dt = datetime.datetime.strptime(time, '%Y-%m-%d %H:%M:%S')
Another way avoiding using the exception handling mechanism is to default the field if not present and just try processing with the one format string:
from datetime import datetime
s = '2010-04-16 16:51:23.123'
dt, secs = s.partition('.')[::2]
print datetime.strptime('{}.{}'.format(dt, secs or '0'), '%Y-%m-%d %H:%M:%S.%f')
if you're using the latest python (3.2+) simple-date will do this kind of thing for you:
>>> from simpledate import *
>>> SimpleDate('2010-04-16 16:51:23.1456')
SimpleDate('2010-04-16 16:51:23.145600', tz='America/Santiago')
>>> SimpleDate('2010-04-16 16:51:23')
SimpleDate('2010-04-16 16:51:23', tz='America/Santiago')
it works by extending the python template format. so you could also write (it's not needed because ISO8601-like formats are handled by default):
>>> SimpleDate('2010-04-16 16:51:23', format='Y-m-d H:M:S(.f)?')
SimpleDate('2010-04-16 16:51:23', tz='America/Santiago')
see how the fractional seconds are (.f)? like a regexp - means it's optional (also, it will add % signs if there are none).
PS and you can access the datetime via an attribute. if you wanted to discard the tzinfo (which is taken from the locale by default - i live in chile, hence America/Santiago above) to get a naive datetime:
>>> SimpleDate('2010-04-16 16:51:23').naive.datetime
datetime.datetime(2010, 4, 16, 16, 51, 23)
I have a process where I read in a bunch of strings in ISO 8601 format at Zulu or UTC time. For example,
2012-06-20T21:15:00Z
2012-06-20T21:16:00Z
2012-06-20T21:17:00Z
2012-06-20T21:18:00Z
I convert the strings into timezone aware python datetime objects and then save them in a binary format as integers by converting them to Unix Timestamps. For example,
dt_str = '2012-06-20T21:15:00Z'
ts = int(mktime(datetime.strptime(dt_str, '%Y-%m-%dT%H:%M:%SZ').timetuple()))
# ts = 1340241300
When I read these timestamps back into another process I would like to instantiate a numpy.datetime64 object directly from the timestamp. The problem is that datetime64 sets the timezone to my local timezone.
np_dt = np.datetime64(ts,'s')
# np_dt = numpy.datetime64('2012-06-20T21:15:00-0400')
Does anyone know of a way that I could read in my timestamp so that it is UTC time? Would I would like for np_dt to equal is numpy.datetime64('2012-06-20T21:15:00-0000')...I think.
Regards
What about setting the timezone for your code.
import os, time
os.environ['TZ'] = 'GMT'
time.tzset()
# then your code
np_dt = np.datetime64(ts,'s')
You can use the dateutil module to help out. First, create a datetime object from the timestamp integer you saved:
>>> ts = 1340241300
>>> import datetime
>>> from dateutil import tz
>>> dt = datetime.datetime.fromtimestamp(ts).replace(tzinfo=tz.tzutc())
>>> dt
datetime.datetime(2012, 6, 20, 21, 15, tzinfo=tzutc())
Then pass it to numpy, which will convert it to the local timezone (I am in -4):
>>> import numpy as np
>>> np.datetime64(dt.isoformat())
numpy.datetime64('2012-06-20T17:15:00-0400')
Judging by the documentation, the only way to do it is to create it from a string that specifies the time zone directly. Thus you'll need to create a datetime.datetime object first and format it to a string with 'Z' appended, then construct the numpy.datetime64 from that.
I understand how to convert a string to a datetime object, but what about a string that has a different time zone? for example "10/07/2011 04:22 CEST"
EST can mean two different timezones: European Summer Time, or Eastern Standard Time. So datetime strings such as 08/07/2011 04:22 EST are ambiguous -- there's no sure-fire way to correctly convert such strings to a timezone-aware datetime.
If you are willing to just make a stab at a possibly correct answer, then
you can generate a mapping between abbreviations like EST and timezone names, make a random choice among the valid timezones, and
then use that timezone to build a timezone-aware datetime:
import dateutil.tz as dtz
import pytz
import datetime as dt
import collections
import random
timezones = collections.defaultdict(list)
for name in pytz.common_timezones:
timezone = dtz.gettz(name)
try:
now = dt.datetime.now(timezone)
except ValueError:
# dt.datetime.now(dtz.gettz('Pacific/Apia')) raises ValueError
continue
abbrev = now.strftime('%Z')
timezones[abbrev].append(name)
date_string, tz_string = '10/07/2011 04:22 CEST'.rsplit(' ', 1)
date = dt.datetime.strptime(date_string, '%m/%d/%Y %H:%M')
print(date)
# 2011-10-07 04:22:00
tz = pytz.timezone(random.choice(timezones[tz_string]))
print(tz)
# Europe/Oslo
date = tz.localize(date)
print(date)
# 2011-10-07 04:22:00+02:00
You should be able to use strptime with a %Z in your format string, but be aware of this note from the Python documentation (http://docs.python.org/library/datetime.html#strftime-strptime-behavior):
"%Z -- If tzname() returns None, %Z is replaced by an empty string. Otherwise %Z is replaced by the returned value, which must be a string. The full set of format codes supported varies across platforms, because Python calls the platform C library’s strftime() function, and platform variations are common."
Can you put the timezone into offset form and use %z instead?