9.4.2.1 today

This is local date (not UTC)

date.today()

#:> datetime.date(2020, 11, 20)

print( date.today() )

#:> 2020-11-20

9.4.2.2 Convert From ISO fromisoformat

strptime is not available for date conversion. It is only for datetime conversion

date.fromisoformat('2011-11-11')

#:> datetime.date(2011, 11, 11)

To convert non-iso format date string to date object, convert to datetime first, then to date

9.4.3.1 replace()

• Replace year/month/day with specified parameter, non specified params will remain unchange.
  
• Example below change only month. You can change year or day in combination

print( date.today() )

#:> 2020-11-20

print( date.today().replace(month=8) )

#:> 2020-08-20

9.4.3.2 weekday(), isoweekday()

For weekday(), Zero being Monday
For isoweekday(), Zero being Sunday

print( date.today().weekday() )

#:> 4

print( date.today().isoweekday() )

#:> 5

weekdays = ['Mon','Tue','Wed','Thu','Fri','Sat','Sun']
wd = date.today().weekday()
print( date.today(), "is day", wd ,"which is", weekdays[wd] )

#:> 2020-11-20 is day 4 which is Fri

9.4.3.3 Formating with isoformat()

isoformat() return ISO 8601 String (YYYY-MM-DD)

date.today().isoformat() # return string

#:> '2020-11-20'

9.4.3.4 Formating with strftime

For complete directive, see below:
https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior

date.today().strftime("%m/%d")

#:> '11/20'

9.4.3.5 isocalendar()

isocalendar return a 3-tuple, (ISO year, ISO week number, ISO weekday).

date.today().isocalendar() ## return tuple 

#:> (2020, 47, 5)

9.5.2.1 now and today

Both now() and today() return current system local datetime, no timezone

print(  dt.datetime.now(), '\n',
        dt.datetime.now().date())

#:> 2020-11-20 14:28:25.898918 
#:>  2020-11-20

dt.datetime.today()

#:> datetime.datetime(2020, 11, 20, 14, 28, 25, 906038)

9.5.2.2 utcnow

dt.datetime.utcnow()

#:> datetime.datetime(2020, 11, 20, 20, 28, 25, 916074)

9.5.2.3 combine() date and time

Apply datetime.combine() module method on both date and time object to get datetime

now = dt.datetime.now()
dt.datetime.combine(now.date(), now.time())

#:> datetime.datetime(2020, 11, 20, 14, 28, 25, 922861)

9.5.2.4 Convert from String strptime()

Use strptime to convert string into datetime object

%I : 12-hour
%H : 24-hour
%M : Minute
%p : AM/PM
%y : 18
%Y : 2018
%b : Mar
%m : month (1 to 12)
%d : day

datetime.strptime('2011-02-25','%Y-%m-%d')

#:> datetime.datetime(2011, 2, 25, 0, 0)

datetime.strptime('9-01-18','%d-%m-%y')

#:> datetime.datetime(2018, 1, 9, 0, 0)

datetime.strptime('09-Mar-2018','%d-%b-%Y')

#:> datetime.datetime(2018, 3, 9, 0, 0)

datetime.strptime('2/5/2018 4:49 PM', '%m/%d/%Y %I:%M %p')

#:> datetime.datetime(2018, 2, 5, 16, 49)

9.5.2.5 Convert from ISO fromisoformat

• fromisoformat() is intend to be reverse of isoformat()
  
• It actually not ISO compliance: when Z or +8 is included at the end of the string, error occur

#s = dt.datetime.now().isoformat()
dt.datetime.fromisoformat("2019-02-05T10:22:33")

#:> datetime.datetime(2019, 2, 5, 10, 22, 33)

9.5.3.1 weekday

datetime.now().weekday()

#:> 4

9.5.3.2 replace

datetime.now().replace(year=1999)

#:> datetime.datetime(1999, 11, 20, 14, 28, 25, 988527)

9.5.3.3 convert to .time()

datetime.now().time()

#:> datetime.time(14, 28, 25, 998462)

9.5.3.4 Convert to .date()

datetime.now().date()

#:> datetime.date(2020, 11, 20)

9.5.3.5 Convert to String

str

str( datetime.now() )

#:> '2020-11-20 14:28:26.024638'

Use strftime()

dt.datetime.now().strftime('%d-%b-%Y')

#:> '20-Nov-2020'

dt.datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%S.%fZ')  ## ISO 8601 UTC

#:> '2020-11-20T20:28:26.048793Z'

Use isoformat()

dt.datetime.utcnow().isoformat()

#:> '2020-11-20T20:28:26.056107'

9.6.2.1 now()

There is unfortunately no single function to extract the current time. Use time() function of an datetime object

datetime.now().time()

#:> datetime.time(14, 28, 26, 105177)