Python Date Functions

1. Introduction

Dates are a very important concept in computer science, especially in processing time, scheduling tasks, and data analysis. Python provides many date functions and libraries that make working with dates simpler and more efficient.

This article introduces commonly used date functions in Python, including date formatting, obtaining the current date and time, date addition and subtraction, and comparisons.

2. time Module

Python’s time module provides several time-related functions. By importing the time module, we can use some common date manipulation functions.

2.1 time.time()

time.time() returns the number of seconds since 00:00, January 1, 1970 (UTC). This timestamp can be used to calculate time intervals or determine the execution time of an operation. Here is an example:

import time

start_time = time.time()

# Perform some time-consuming operations

time.sleep(1)

end_time = time.time()
elapsed_time = end_time - start_time

print("elapsed", elapsed_time, "seconds")

Output:

1.0008764266967773 seconds have passed

2.2 time.localtime()

time.localtime() The function returns a time tuple containing the current time. This time tuple contains information such as year, month, day, hour, minute, and second. Here’s an example:

import time

current_time = time.localtime()

year = current_time.tm_year
month = current_time.tm_mon
day = current_time.tm_mday
hour = current_time.tm_hour
minute = current_time.tm_min
second = current_time.tm_sec

print(“Current time:”, year, “Year”, month, “Month”, day, “Day”, hour, “Hour”, minute, “Minute”, second, “Second”)

output:

Current time: July 12, 2022, 18:30:00


<h2>3. Datetime Module

<p>Python's datetime module provides higher-level date and time operations. The datetime module allows us to easily obtain the current date and time, perform date calculations, and perform comparisons. </p>
<p>Below is an introduction to some commonly used datetime functions. </p>
<h3>3.1 Obtaining the Current Date and Time</h3>
<p>Use the <code>datetime.datetime.now() function to obtain the current date and time. 

import datetime

current_date_time = datetime.datetime.now()

print("Current date and time:", current_date_time)

Output: 
Current date and time: 2022-07-12 18:30:00.123456

3.2 Formatting Dates
You can use the strftime() function to format a date into a specific string format. Here are some commonly used format strings:

%Y: Four-digit full year
%m: Two-digit month (01 to 12)
%d: Two-digit day (01 to 31)
%H: Hour in 24-hour format (00 to 23)
%M: Minutes (00 to 59)
%S: Seconds (01 to 61, with 60 and 61 used for leap seconds)

import datetime

current_date_time = datetime.datetime.now()

formatted_date_time = current_date_time.strftime("%Y-%m-%d %H:%M:%S")

print("Formatted date and time:", formatted_date_time)

Output:
Formatted date and time: 2022-07-12 18:30:00

3.3 Date Addition and Subtraction
You can use timedelta objects to perform date addition and subtraction operations. 
import datetime

current_date = datetime.date.today()
one_day_delta = datetime.timedelta(days=1)

yesterday = current_date - one_day_delta
tomorrow = current_date + one_day_delta

print("Yesterday's date:", yesterday)
print("Tomorrow's date:", tomorrow)

Output: 
Yesterday's date: 2022-07-11
Tomorrow's date: 2022-07-13

3.4 Date Comparison
Dates can be compared using comparison operators. 
import datetime

current_date = datetime.date.today()
future_date = datetime.date(2022, 12, 31)

if current_date < future_date:
print("The current date is before the future date")
else:
print("The current date is after the future date")

Output: 
The current date is before the future date

4. Calendar Module
Python's calendar module provides several calendar-related functions. Using the calendar module, we can easily generate and manipulate calendars. 
Below is an introduction to some commonly used calendar functions. 
4.1 calendar.calendar()
calendar.calendar(year) returns a calendar for the specified year. By default, each week starts on Monday and displays seven days per line. 
import calendar

cal = calendar.calendar(2022)

print(cal)