Python – Date and Time

Often in data science we need analysis which is based on temporal values. Python can handle the various formats of date and time gracefully. The datetime library
provides necessary methods and functions to handle the following scenarios.

• Date Time Representation
• Date Time Arithmetic
• Date Time Comparison
  We will study them one by one.

  Date Time Representation

  A date and its various parts are represented by using different datetime functions. Also, there are format specifiers which play a role in displaying the alphabetical parts of a date like name of the month or week day. The following code shows today's date and various parts of the date.

  import datetime
  print 'The Date Today is  :', datetime.datetime.today()
  today_date = datetime.date.today()
  print today_date
  print 'This Year   :', today_date.year
  print 'This Month    :', today_date.month
  print 'Month Name:',today_date.strftime('%B')
  print 'This Week Day    :', today_date.day
  print 'Week Day Name:',today_date.strftime('%A')

  When we execute the above code, it produces the following result.

  The Date Today is  : 2021-02-27 15:38:35.835000
  2021-02-27
  This Year   : 2021
  This Month    : 02
  Month Name: February
  This Week Day    : 27
  Week Day Name: Saturday

  Date Time Arithmetic

  For calculations involving dates we store the various dates into variables and apply the relevant mathematical operator to these variables.

  import datetime
  #Capture the First Date
  d1 = datetime.date(2021, 2, 27)
  print 'day1:', d1.ctime()
  # Capture the Second Date
  d2 = datetime.date(2019, 6, 18)
  print 'day2:', d2.ctime()
  # Find the difference between the dates
  print 'Number of Days:', day1-day2
  today_date  = datetime.date.today()
  # Create a delta of Four Days
  no_days = datetime.timedelta(days=4)
  # Use Delta for Past Date
  before_four_days = today_date - no_days
  print 'Before Four Days:', before_four_days
  # Use Delta for future Date
  after_four_days = today_date + no_days
  print 'After Four Days:', after_four_days

  When we execute the above code, it produces the following result.

  day1: Sat Feb 27 00:00:00 2021
  day2: Fri Jun 06 00:00:00 2019
  Number of Days: 178 days, 0:00:00
  Before Four Days: 2021-02-23
  After Four Days: 2021-03-03

  Date Time Comparison

  Date and time are compared using logical operators. But we must be careful in comparing the right parts of the dates with each other. In the below examples
  we take the future and past dates and compare them using the python if clause along with logical operators.

  import datetime
  today_date  = datetime.date.today()
  print 'Today is: ', today_date
  # Create a delta of Four Days
  no_days = datetime.timedelta(days=4)
  # Use Delta for Past Date
  before_four_days = today_date - no_days
  print 'Before Four Days:', before_four_days
  after_four_days =  today_date + no_days
  d1 = datetime.date(2021,2,27)
  print 'date1:',today_date
  if d1 == before_four_days :
  print 'Same Dates'
  if d1 > date1:
  print 'Past Date'
  if d1 < after_four_days:
  print 'Future Date'

  When we execute the above code, it produces the following result.

  Today is:  2021-02-27
  Before Four Days: 2021-02-23
  date1: 2018-04-04
  Past Date
  Future Date