30-Days-Of-Python/16_Day/16_python_datetime.md

30 Days Of Python: Day 16 - Python Date time

_{Author: Asabeneh Yetayeh
First Edition: Nov 22 - Dec 22, 2019}

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• 📘 Day 16
  • Python datetime
    • Getting the datetime Information
    • Formating Datetime Output Using Strftime
    • String to Time Using Strptime
    • Use Date from Datetime
    • Time Object to Represent Time
    • Difference Between Two Datetime
    • Difference Between Two Dates and Times Using Timedelata
  • 💻 Exercises: Day 16

📘 Day 16

Python datetime

Python has datetime module to handle date and time.

import datetime
print(dir(datetime))
['MAXYEAR', 'MINYEAR', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'date', 'datetime', 'datetime_CAPI', 'sys', 'time', 'timedelta', 'timezone', 'tzinfo']

With dir or help built-in commands it is possible to know the available functions in a certain module. As you can see, in the datetime module there are many functions, but we will focus on date, datetime, time and timedelta. Let's see them one by one.

Getting the datetime information

from datetime import datetime
now = datetime.now()
print(now)                      # 2019-12-04 23:34:46.549883
day = now.day                   # 4
month = now.month               # 12
year = now.year                 # 2019
hour = now.hour                 # 23
minute = now.minute             # 38
second = now.second
timestamp = now.timestamp()
print(day, month, year, hour, minute)
print('timestamp', timestamp)
print(f'{day}/{month}/{year}, {hour}:{minute}')  # 4/12/2019, 23:38

Formating datetime output using strftime

from datetime import datetime
new_year = datetime(2020, 1, 1)
print(new_year)      # 2020-01-01 00:00:00
day = new_year.day
month = new_year.month
year = new_year.year
hour = new_year.hour
minute = new_year.minute
second = new_year.second
print(day, month, year, hour, minute) #1 1 2020 0 0
print(f'{day}/{month}/{year}, {hour}:{minute}')  # 1/1/2020, 0:0

Time formating

from datetime import datetime
# current date and time
now = datetime.now()
t = now.strftime("%H:%M:%S")
print("time:", t)
time_one = now.strftime("%m/%d/%Y, %H:%M:%S")
# mm/dd/YY H:M:S format
print("time one:", time_one)
time_two = now.strftime("%d/%m/%Y, %H:%M:%S")
# dd/mm/YY H:M:S format
print("time two:", time_two)

time: 01:05:01
time one: 12/05/2019, 01:05:01
time two: 05/12/2019, 01:05:01

Here are all the strftime symbols we use to format time. A reference of all the legal format codes.

String to time using strptime

from datetime import datetime
date_string = "5 December, 2019"
print("date_string =", date_string)
date_object = datetime.strptime(date_string, "%d %B, %Y")
print("date_object =", date_object)

date_string = 5 December, 2019
date_object = 2019-12-05 00:00:00

Use date from datetime

from datetime import date
d = date(2020, 1, 1)
print(d)
print('Current date:', d.today())    # 2019-12-05
# date object of today's date
today = date.today()
print("Current year:", today.year)   # 2019
print("Current month:", today.month) # 12
print("Current day:", today.day)     # 5

Time object to represent time

from datetime import time
# time(hour = 0, minute = 0, second = 0)
a = time()
print("a =", a)
# time(hour, minute and second)
b = time(10, 30, 50)
print("b =", b)
# time(hour, minute and second)
c = time(hour=10, minute=30, second=50)
print("c =", c)
# time(hour, minute, second, microsecond)
d = time(10, 30, 50, 200555)
print("d =", d)

output
a = 00:00:00
b = 10:30:50
c = 10:30:50
d = 10:30:50.200555

Difference between two datetime

today = date(year=2019, month=12, day=5)
new_year = date(year=2020, month=1, day=1)
time_left_for_newyear = new_year - today
# Time left for new year:  27 days, 0:00:00
print('Time left for new year: ', time_left_for_newyear)

t1 = datetime(year = 2019, month = 12, day = 5, hour = 0, minute = 59, second = 0)
t2 = datetime(year = 2020, month = 1, day = 1, hour = 0, minute = 0, second = 0)
diff = t2 - t1
print('Time left for new year:', diff) # Time left for new year: 26 days, 23: 01: 00

Difference between two dates and times using timedelata

from datetime import timedelta
t1 = timedelta(weeks=12, days=10, hours=4, seconds=20)
t2 = timedelta(days=7, hours=5, minutes=3, seconds=30)
t3 = t1 - t2
print("t3 =", t3)

    date_string = 5 December, 2019
    date_object = 2019-12-05 00:00:00
    t3 = 86 days, 22:56:50

💻 Exercises: Day 16

1. Get the current day, month, year, hour, minute and timestamp from time date module
2. Format the current date using in this format: "%m/%d/%Y, %H:%M:%S")
3. Today is 5 December, 2019. Change this time string to time.
4. Calculate the time difference from now to new year.
5. Calculate the time difference between 1 January 1970 and now.
6. Think about for what you can you use datetime module,
   • Time series analysis
   • To get time stamp of any activities in an application
   • And many other users

🎉 CONGRATULATIONS ! 🎉

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