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Basic datetime objects usage:

The datetime module contains three primary types of objects - date, time, and datetime.

Date:

import datetimetoday = datetime.date.today()new_year = datetime.date(2019, 1, 1)print(new_year)

Output:

2019-01-01

Time:

import datetime#Time objectnoon = datetime.time(12, 0, 0)print(noon)

Output:

12:00:00

Date Time:

import datetime# Current datetimenow = datetime.datetime.now()print(now)

Output:

2019-11-01 06:16:18.526734

Date Time:

import datetime# Datetime objectmillenium_turn = datetime.datetime(2019, 1, 1, 0, 0, 0)print(millenium_turn)

Output:

2019-01-01 00:00:00

Iterate over dates:

Print from a start date to some end date.

import datetime# The size of each step in daysday_delta = datetime.timedelta(days=1)start_date = datetime.date.today()end_date = start_date + 7*day_deltafor i in range((end_date - start_date).days):    print(start_date + i*day_delta)

Output:

2019-11-012019-11-022019-11-032019-11-042019-11-052019-11-062019-11-07

Computing time differences:

The timedelta module is used to compute differences between times:

from datetime import datetime, timedeltanow = datetime.now()then = datetime(2019, 5, 23)print(then)

Output:

2019-05-23 00:00:00

Specifying time is optional when creating a new datetime object

from datetime import datetime, timedeltanow = datetime.now()then = datetime(2019, 5, 23)delta = now-thenprint(delta)

Output:

162 days, 9:10:42.599772

delta is of type timedelta:

from datetime import datetime, timedeltanow = datetime.now()then = datetime(2019, 5, 23)delta = now-thenprint(delta.days)# 60print(delta.seconds)# 40826

Output:

16233296

To get n day's after and n day's before date we could use:

n day's after date:

from datetime import date, timedeltacurrent_date = date.today().isoformat()   days_after = (date.today()+timedelta(days=30)).isoformat()  print("\nCurrent Date: ",current_date)print("30 days after current date : ",days_after)

Output:

Current Date:  2019-11-0230 days after current date :  2019-12-02

n day's before date:

from datetime import date, timedeltacurrent_date = date.today().isoformat()   days_before = (date.today()-timedelta(days=30)).isoformat()print("\nCurrent Date: ",current_date)print("30 days before current date: ",days_before)

Output:

Current Date:  2019-11-0230 days before current date:  2019-10-03

Converting timestamp to date time:

The datetime module can convert a POSIX timestamp to a ITC datetime object.

The Epoch is January 1st, 1970 midnight.

import timefrom datetime import datetimeseconds_since_epoch=time.time()  #1469182681.709utc_date=datetime.utcfromtimestamp(seconds_since_epoch)print(utc_date)

Output:

2019-11-01 09:53:20.657171

Simple date arithmetic:

import datetimetoday = datetime.date.today()print('Today:', today)yesterday = today - datetime.timedelta(days=1)print('Yesterday:', yesterday)tomorrow = today + datetime.timedelta(days=1)print('Tomorrow:', tomorrow)print('Time between tomorrow and yesterday:', tomorrow - yesterday)

Output:

Today: 2019-11-01Yesterday: 2019-10-31Tomorrow: 2019-11-02Time between tomorrow and yesterday: 2 days, 0:00:00

Subtracting months from a date:

import calendarfrom datetime import datedef monthdelta(date, delta):    m, y = (date.month+delta) % 12, date.year + ((date.month)+delta-1) // 12    if not m: m = 12    d = min(date.day, calendar.monthrange(y, m)[1])    return date.replace(day=d,month=m, year=y)next_month = monthdelta(date.today(), 1) #datetime.date(2019, 10, 23)print(next_month)

Output:

2019-12-01

Using the dateutils module:

import datetimeimport dateutil.relativedeltad = datetime.datetime.strptime("2019-03-31", "%Y-%m-%d")d2 = d - dateutil.relativedelta.relativedelta(months=1)  #datetime.datetime(2019, 2, 28, 0, 0)print(d2)

Output:

2019-02-28 00:00:00

Switching between time zones:

To switch between time zones, we need datetime objects that are timezone-aware.

from datetime import datetimefrom dateutil import tzutc = tz.tzutc()local = tz.tzlocal()utc_now = datetime.utcnow()utc_now # Not timezone-aware.utc_now = utc_now.replace(tzinfo=utc)utc_now # Timezone-aware.local_now = utc_now.astimezone(local)local_now # Converted to local time.print(local_now)

Output:

2019-11-01 10:10:09.685012+00:00

Fuzzy datetime parsing (extracting datetime out of a text):

from dateutil.parser import parsedt = parse("Today is January 1, 2019 at 8:21:00AM", fuzzy=True)print(dt)

Output:

2019-01-01 08:21:00

Get an ISO 8601 timestamp:

Without timezone, with microseconds:

from datetime import datetimeprint (datetime.now().isoformat())

Output:

2019-11-01T10:42:00.720818

With timezone, with microseconds:

from datetime import datetimefrom dateutil.tz import tzlocalprint (datetime.now(tzlocal()).isoformat())

Output:

2019-11-01T10:46:20.965506+00:00

With timezone, without microseconds:

from datetime import datetimefrom dateutil.tz import tzlocalprint (datetime.now(tzlocal()).replace(microsecond=0).isoformat())

Output:

2019-11-01T10:49:58+00:00

Parsing a string with a short time zone name into a timr zone aware datetime object:

from dateutil import tzfrom dateutil.parser import parseET = tz.gettz('US/Eastern')CT = tz.gettz('US/Central')MT = tz.gettz('US/Mountain')PT = tz.gettz('US/Pacific')us_tzinfos = {'CST': CT, 'CDT': CT,              'EST': ET, 'EDT': ET,              'MST': MT, 'MDT': MT,              'PST': PT, 'PDT': PT}dt_est = parse('2018-1-2 04:00:00 EST', tzinfos=us_tzinfos)dt_pst = parse('2019-3-11 16:00:00 PST', tzinfos=us_tzinfos)print (dt_est)print (dt_pst)

Output:

2018-01-02 04:00:00-05:002019-03-11 16:00:00-07:00

Parsing an arbitrary ISO 8601 timestamp with minimal libraries:

Python has only limited support for parsing ISO 8601 timestamps and for strptime you need to know exactly what format it is in. The stringification of a datetime is an ISO 8601 timestamp, with space as a separator and 6 digit fraction:

import datetimeprint (str(datetime.datetime(2019, 7, 22, 9, 25, 59, 555555)))

Output:

2019-07-22 09:25:59.555555

but if the fraction is 0, no fractional part is output

import datetimeprint(str(datetime.datetime(2019, 7, 22, 9, 25, 59, 0)))

Output:

2019-07-22 09:25:59.555555

Parsing a string into a timezone aware datetime object:

Python 3.2+ has support for %z format when parsing a string into a datetime object.

UTC offset in the form +HHMM or -HHMM (empty string if the object is naive).

import datetimedt = datetime.datetime.strptime("2019-04-15T08:27:18-0500", "%Y-%m-%dT%H:%M:%S%z")print(dt)

Output:

2019-04-15 08:27:18-05:00

Fixed Offset Time Zones

from datetime import datetime, timedelta, timezoneJST = timezone(timedelta(hours=+9))dt = datetime(2019, 1, 1, 12, 0, 0, tzinfo=JST)print(dt)# 2019-01-01 12:00:00+09:00print(dt.tzname())# UTC+09:00dt = datetime(2019, 1, 1, 12, 0, 0, tzinfo=timezone(timedelta(hours=9), 'JST'))print(dt.tzname)# 'JST'

Output:

2019-01-01 12:00:00+09:00UTC+09:00<built-in method tzname of datetime.datetime object at 0x7f91a9437360>

Zones with daylight savings time using third party library:

Use the tz.gettz() method to get a time zone object, which can then be passed directly to the datetime constructor:

from datetime import datetimefrom dateutil import tzlocal = tz.gettz() # Local timePT = tz.gettz('US/Pacific') # Pacific timedt_l = datetime(2019, 1, 1, 12, tzinfo=local) # I am in ESTdt_pst = datetime(2019, 1, 1, 12, tzinfo=PT)dt_pdt = datetime(2019, 7, 1, 12, tzinfo=PT) # DST is handled automaticallyprint(dt_l)# 2019-01-01 12:00:00-05:00print(dt_pst)# 2019-01-01 12:00:00-08:00print(dt_pdt)# 2019-07-01 12:00:00-07:00

Output:

2019-01-01 12:00:00+00:002019-01-01 12:00:00-08:002019-07-01 12:00:00-07:00

List of the Date format codes:

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