How to Parse Dates with -0400 Timezone String in Python

Parse Date string to datetime with timezone

Using dateutil.parser you can directly parse your date correctly.

Note that CST is an ambiguous timezone, so you need to specify which one you mean. You can either do this directly in the tzinfos parameter of the parse() call or you can define a dictionary that has mappings for timezones and pass this. In this dict, you can either specify the offset, e.g.

timezone_info = {
        "CDT": -5 * 3600,
        "CEST": 2 * 3600,
        "CST": 8 * 3600
}

parser.parse(r, tzinfos=timezone_info)

or (using gettz) directly specify a timezone:

timezone_info = {
        "CDT": gettz("America/Chicago"),
        "CEST": gettz("Europe/Berlin"),
        "CST": gettz("Asia/Shanghai")
}

parser.parse(r, tzinfos=timezone_info)

See also the dateutil.parser documentation and the answers to this SO question.

Be aware that the latter approach is tricky if you have a location with daylight saving time! Depending on the date you apply it to, gettz("America/Chicago") will have UTC-5 or UTC-6 as a result (as Chicago switches between Central Standard Time and Central Daylight Time). So depending on your input data, the second example may actually not really be correct and yield the wrong outcome! Currently, China observes China Standard Time (CST) all year, so for your use case it makes no difference (may depend on your date range though).

Overall:

from dateutil import parser
from dateutil.tz import gettz

timezone_info = {"CST": gettz("Asia/Shanghai")}

r = 'Thu Dec 17 08:56:41 CST 2020'
d = parser.parse(r, tzinfos=timezone_info)

print(d)
print(d.strftime('%Y-%m-%d %H:%M:%S %Z%z'))

gets you

2020-12-17 08:56:41+08:00
2020-12-17 08:56:41 CST+0800

EDIT: Printing the human readable timezone name instead of the abbreviated one name is just a little more complicated with this approach, as dateutil.tz.gettz() gets you a tzfile that has no attribute which has just the name. However, you can obtain it via the protected _filename using split():

print(d.strftime('%Y-%m-%d %H:%M:%S') + " in " + "/".join(d.tzinfo._filename.split('/')[-2:]))

yields

2020-12-17 08:56:41+08:00 in Asia/Shanghai

This of course only works if you used gettz() to set the timezone in the first place.

EDIT 2: If you know that all your dates are in CST anyway, you can also ignore the timezone when parsing. This gets you naive (or unanware) datetimes which you can then later add a human readable timezone to. You can do this using replace() and specify the timezone either as shown above using gettz() or using timezone(() from the pytz module:

from dateutil import parser
from dateutil.tz import gettz
import pytz

r = 'Thu Dec 17 08:56:41 CST 2020'
d = parser.parse(r, ignoretz=True)

d_dateutil = d.replace(tzinfo=gettz('Asia/Shanghai'))
d_pytz = d.replace(tzinfo=pytz.timezone('Asia/Shanghai'))

Note that depending on which module you use to add the timezone information, the class of tzinfo differs. For the pytz object, there is a more direct way of accessing the timezone in human readable form:

print(type(d_dateutil.tzinfo))
print("/".join(d_dateutil.tzinfo._filename.split('/')[-2:]))

print(type(d_pytz.tzinfo))
print(d_pytz.tzinfo.zone)

produces

<class 'dateutil.tz.tz.tzfile'>
Asia/Shanghai
<class 'pytz.tzfile.Asia/Shanghai'>
Asia/Shanghai

Parse a date in a specific timezone with Python

There are three steps:

1. Convert the date string into a naive datetime object:

   from datetime import datetime 
   
   dt = datetime(*map(int ,'2015-01-01'.split('-')))
   

2. Get a timezone-aware datetime object:

   import pytz # $ pip install pytz
   
   aware = pytz.timezone("US/Mountain").localize(dt, is_dst=None)
   

   is_dst=None raises an exception for ambiguous or non-existing times. Here're more details about what is is_dst flag and why do you need it, see "Can I just always set is_dst=True?" section

3. Get POSIX timestamp:

   timestamp = aware.timestamp()
   

   .timestamp() is available since Python 3.3+. See multiple solutions for older Python versions.

Extract UTC date from timezone aware string

Assuming the format is consistent in your data (length of the strings is constant), you can do a bit of string slicing to separate date/time and UTC offset. Parse the first to datetime and add the latter as a timezone constructed from a timedelta. Then convert to UTC.

Ex:

from datetime import datetime, timedelta, timezone

s = '2021-04-15T21:53:00:000-06'

# first part to datetime
dt = datetime.fromisoformat(s[:-3])

# set time zone
dt = dt.replace(tzinfo=timezone(timedelta(hours=int(s[-3:]))))

# to UTC
dt_utc = dt.astimezone(timezone.utc)

print(dt_utc.date())
# 2021-04-16

Note that this will fail if the format is not consistent, e.g. if some strings have +0530 while others only have e.g. -06.

In that case, another option is to use strptime, but that requires modifying the input as well. %z expects ±HH:MM or ±HHMM, so you can add the minutes like

if len(s) == 26: # minutes missing
    s += '00'

dt = datetime.strptime(s, "%Y-%m-%dT%H:%M:%S:%f%z")

and then convert to UTC as described above.

Parse Datetime with +0 timezone

Any ideas what I have overseen?

strftime.org claims that %z

UTC offset in the form ±HHMM[SS[.ffffff]] (empty string if the object
is naive).

this mean that it must contain at least 4 digits after + or - (HHMM part, which is compulsory), taking this is account Dec 03 2020 01: +0 is not compliant with used format string, whilst Dec 03 2020 01: +0000 is

import datetime
dtObj = datetime.datetime.strptime("Dec 03 2020 01: +0000", '%b %d %Y %I: %z')
print(dtObj)

gives output

2020-12-03 01:00:00+00:00

How to convert date string with timezone to datetime in python

You could use %z to parse timezone info:

>>> from datetime import datetime, timezone
>>> datetime.strptime(str, "%Y-%m-%dT%H:%M:%S%z")
datetime.datetime(2015, 8, 23, 3, 36, 30, tzinfo=datetime.timezone(datetime.timedelta(days=-1, seconds=68400)))

Then, if you want to convert this datetime to UTC (which I assume is your goal since you say you want to compare datetimes), you could use astimezone method:

>>> datetime.strptime(str, "%Y-%m-%dT%H:%M:%S%z").astimezone(timezone.utc)
datetime.datetime(2015, 8, 23, 8, 36, 30, tzinfo=datetime.timezone.utc)

Back in string format:

>>> datetime.strptime(str, "%Y-%m-%dT%H:%M:%S%z").astimezone(timezone.utc).strftime("%Y-%m-%d %H:%M:%S")
'2015-08-23 08:36:30'

Datetime Time Zone Scraping Python

Note %z in strptime() is for timezone offsets not names and %Z only accepts certain values for time zones. For details see API docs.

Simplest option is to use dateparser module to parse dates with time zone names (e.g. EDT).

import dateparser

s = "Jun 1, 2022 2:49PM EDT"
d =  dateparser.parse(s)
print(d)

Output:

2022-06-01 14:49:00-04:00

Many of the date modules (e.g. dateutil and pytz) have timezone offsets defined for "EST", "PST", etc. but "EDT" is less common. These modules would need you to define the timezone with the offset as UTC-04:00.

import dateutil.parser

s = "Jun 1, 2022 2:49PM EDT"
tzinfos = {"EDT": -14400}
d = dateutil.parser.parse(s, tzinfos=tzinfos)
print(d)

Output:

2022-06-01 14:49:00-04:00

Parsing date/time string with timezone abbreviated name in Python?

That probably won't work because those abbreviations aren't unique. See this page for details. You might wind up just having to manually handle it yourself if you're working with a known set of inputs.

How can I parse a custom string as a timezone aware datetime?

Hmm How about maybe:

import re
import datetime
foo = "18 January 2022, 14:50 GMT-5"
bar = re.sub(r"[+-]\d+$", lambda m: "{:05d}".format(100 * int(m.group())), foo)
print(datetime.datetime.strptime(bar, "%d %B %Y, %H:%M %Z%z" ))

I think that gives you:

2022-01-18 14:50:00-05:00

Convert string with timezone included into datetime object

It is a common misconception that %Z can parse arbitrary abbreviated time zone names. It cannot. See especially the "Notes" section #6 under technical detail in the docs.

You'll have to do that "by hand" since many of those abbreviations are ambiguous. Here's an option how to deal with it using only the standard lib:

from datetime import datetime
from zoneinfo import ZoneInfo

# we need to define which abbreviation corresponds to which time zone
zoneMapping = {'PDT' : ZoneInfo('America/Los_Angeles'),
               'PST' : ZoneInfo('America/Los_Angeles'),
               'CET' : ZoneInfo('Europe/Berlin'),
               'CEST': ZoneInfo('Europe/Berlin')}

# some example inputs; last should fail
timestrings = ('Jun 8, 2021 PDT', 'Feb 8, 2021 PST', 'Feb 8, 2021 CET',
               'Aug 9, 2020 WTF')

for t in timestrings:
    # we can split off the time zone abbreviation
    s, z = t.rsplit(' ', 1)
    # parse the first part to datetime object
    # and set the time zone; use dict.get if it should be None if not found
    dt = datetime.strptime(s, "%b %d, %Y").replace(tzinfo=zoneMapping[z])
    print(t, "->", dt)

gives

Jun 8, 2021 PDT -> 2021-06-08 00:00:00-07:00
Feb 8, 2021 PST -> 2021-02-08 00:00:00-08:00
Feb 8, 2021 CET -> 2021-02-08 00:00:00+01:00

Traceback (most recent call last):

    dt = datetime.strptime(s, "%b %d, %Y").replace(tzinfo=zoneMapping[z])

KeyError: 'WTF'

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