16_python_datetime.md

30 Days Of Python: Day 16 - Python Date time

_{Author: Asabeneh Yetayeh
Second Edition: July, 2021}

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• 📘 Day 16
  • Python datetime
    • Getting datetime Information
    • Formatting Date Output Using strftime
    • String to Time Using strptime
    • Using date from datetime
    • Time Objects to Represent Time
    • Difference Between Two Points in Time Using
    • Difference Between Two Points in Time Using timedelata
  • 💻 Exercises: Day 16

📘 Day 16

Python datetime

Python has got 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 se see them one by one.

Getting datetime Information

from datetime import datetime
now = datetime.now()
print(now)                      # 2021-07-08 07:34:46.549883
day = now.day                   # 8
month = now.month               # 7
year = now.year                 # 2021
hour = now.hour                 # 7
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}')  # 8/7/2021, 7:38

Timestamp or Unix timestamp is the number of seconds elapsed from 1st of January 1970 UTC.

Formatting Date 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

Formatting date time using strftime method and the documentation can be found here.

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. An example of all the formats for this module.

String to Time Using strptime

Here is a documentation hat helps to understand the format.

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

Using 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 Objects 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 Points in Time Using

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 Points in Time 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

🌕 You are an extraordinary. You are 16 steps a head to your way to greatness. Now do some exercises for your brain and muscles.

💻 Exercises: Day 16

1. Get the current day, month, year, hour, minute and timestamp from datetime module
2. Format the current date using 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 between now and new year.
5. Calculate the time difference between 1 January 1970 and now.
6. Think, what can you use the datetime module for? Examples:
   • Time series analysis
   • To get a timestamp of any activities in an application
   • Adding posts on a blog

🎉 CONGRATULATIONS ! 🎉

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