python datetime

import datetime

today = datetime.datetime.now()
date_time = today.strftime("%m/%d/%Y, %H:%M:%S")
print("date and time:",date_time)

| Directive | Meaning                                                        | Example                 | 
|-----------|------------------------------------------------------------------------------------------|
|%a         | Abbreviated weekday name.                                      | Sun, Mon, ..            | 
|%A         | Full weekday name.                                             | Sunday, Monday, ...     | 
|%w         | Weekday as a decimal number.                                   | 0, 1, ..., 6            | 
|%d         | Day of the month as a zero-padded decimal.                     | 01, 02, ..., 31         | 
|%-d        | Day of the month as a decimal number.                          | 1, 2, ..., 30           | 
|%b         | Abbreviated month name.                                        | Jan, Feb, ..., Dec      | 
|%B         | Full month name.                                               | January, February, ...  | 
|%m         | Month as a zero-padded decimal number.                         | 01, 02, ..., 12         | 
|%-m        | Month as a decimal number.                                     | 1, 2, ..., 12           | 
|%y         | Year without century as a zero-padded decimal number.          | 00, 01, ..., 99         | 
|%-y        | Year without century as a decimal number.                      | 0, 1, ..., 99           | 
|%Y         | Year with century as a decimal number.                         | 2013, 2019 etc.         | 
|%H         | Hour (24-hour clock) as a zero-padded decimal number.          | 00, 01, ..., 23         | 
|%-H        | Hour (24-hour clock) as a decimal number.                      | 0, 1, ..., 23           | 
|%I         | Hour (12-hour clock) as a zero-padded decimal number.          | 01, 02, ..., 12         | 
|%-I        | Hour (12-hour clock) as a decimal number.                      | 1, 2, ... 12            | 
|%p         | Locale’s AM or PM.                                             | AM, PM                  | 
|%M         | Minute as a zero-padded decimal number.                        | 00, 01, ..., 59         | 
|%-M        | Minute as a decimal number.                                    | 0, 1, ..., 59           | 
|%S         | Second as a zero-padded decimal number.                        | 00, 01, ..., 59         | 
|%-S        | Second as a decimal number.                                    | 0, 1, ..., 59           | 
|%f         | Microsecond as a decimal number, zero-padded on the left.      | 000000 - 999999         | 
|%z         | UTC offset in the form +HHMM or -HHMM.                         |                         | 
|%Z         | Time zone name.                                                |                         | 
|%j         | Day of the year as a zero-padded decimal number.               | 001, 002, ..., 366      | 
|%-j        | Day of the year as a decimal number. 1, 2, ..., 366            |                         | 
|%U         | Week number of the year (Sunday as the first day of the week). | 00, 01, ..., 53         | 
|%W         | Week number of the year (Monday as the first day of the week). | 00, 01, ..., 53         | 
|%c         | Locale’s appropriate date and time representation.             | Mon Sep 30 07:06:05 2013|
|%x         | Locale’s appropriate date representation.                      | 09/30/13                | 
|%X         | Locale’s appropriate time representation.                      | 07:06:05                | 
|%%         | A literal '%' character.                                       | %                       | 

%a - Abbreviated weekday name. (Sun, Mon, ...)
%A - Full weekday name. (Sunday, Monday, ...)
%w - Weekday as a decimal number. (0, 1, ..., 6)
%d - Day of the month as a zero-padded decimal. (01, 02, ..., 31)
%-d - Day of the month as a decimal number. (1, 2, ..., 30)
%b - Abbreviated month name. (Jan, Feb, ..., Dec)
%B - Full month name. (January, February, ...)
%m - Month as a zero-padded decimal number. (01, 02, ..., 12)
%-m - Month as a decimal number. (1, 2, ..., 12)
%y - Year without century as a zero-padded decimal number. (00, 01, ..., 99)
%-y - Year without century as a decimal number. (0, 1, ..., 99)
%Y - Year with century as a decimal number. (2013, 2019 etc.)
%H - Hour (24-hour clock) as a zero-padded decimal number. (00, 01, ..., 23)
%-H - Hour (24-hour clock) as a decimal number. (0, 1, ..., 23)
%I - Hour (12-hour clock) as a zero-padded decimal number. (01, 02, ..., 12)
%-I - Hour (12-hour clock) as a decimal number. (1, 2, ... 12)
%p - Locale’s AM or PM. (AM, PM)
%M - Minute as a zero-padded decimal number. (00, 01, ..., 59)
%-M - Minute as a decimal number. (0, 1, ..., 59)
%S - Second as a zero-padded decimal number. (00, 01, ..., 59)
%-S - Second as a decimal number. (0, 1, ..., 59)
%f - Microsecond as a decimal number, zero-padded on the left.  (000000 - 999999)
%z - UTC offset in the form +HHMM or -HHMM.  
%Z - Time zone name. 
%j - Day of the year as a zero-padded decimal number. (001, 002, ..., 366)
%-j - Day of the year as a decimal number. (1, 2, ..., 366)
%U - Week number of the year (Sunday as the first day of the week). All days in a new year preceding the first Sunday are considered to be in week 0. (00, 01, ..., 53)
%W - Week number of the year (Monday as the first day of the week). All days in a new year preceding the first Monday are considered to be in week 0. (00, 01, ..., 53)
%c - Locale’s appropriate date and time representation. (Mon Sep 30 07:06:05 2013)
%x - Locale’s appropriate date representation. (09/30/13)
%X - Locale’s appropriate time representation. (07:06:05)
%% - A literal '%' character. (%)

from datetime import datetime
now = datetime.now()
print (now.strftime("%Y-%m-%d %H:%M:%S"))


Output: 2020-06-19 10:34:45

from datetime import datetime as d
date = d.now()
print(now.strftime("%Y-%m-%d %H:%M:%S"))

df['date_time']=pd.to_datetime(df['date_time'], format='%d-%m-%Y %H.%M.%S')
#fomrat given in code should match the format of the feature
#here--> df['date_time'][0]=10-03-2004 18.00.00
#watchout for the blanks  '-' '.'

from datetime import datetime

print(datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3])

from datetime import datetime, timedelta

d = datetime.today() - timedelta( days = 1)

print( d.strftime( "%Y%m%d" ) )

from datetime import datetime

custom_date_time = datetime(2021, 7, 23, 17, 30, 29, 431717)
print(custom_date_time)

# Output:
# 2021-07-23 17:30:29.431717

from datetime import datetime

dt_obj = datetime.strptime('20.12.2016 09:38:42,76',
                           '%d.%m.%Y %H:%M:%S,%f')
millisec = dt_obj.timestamp() * 1000

print(millisec)

from datetime import datetime

date_string = "21 June, 2018"

print("date_string =", date_string)
print("type of date_string =", type(date_string))

date_object = datetime.strptime(date_string, "%d %B, %Y")

print("date_object =", date_object)
print("type of date_object =", type(date_object))

from datetime import date
f_date = date(2014, 7, 2)
l_date = date(2014, 7, 11)
delta = l_date - f_date
print(delta.days)