How to get week number in Python? (4 Different Methods)

Wondering how to get week number in Python? Let’s find how you can find the the number in python by 4 different methods.

Working with dates and time is a common task in many Python projects.

One frequently encountered requirement is to determine the week number for a given date.

In this blog post, we will explore various methods to obtain the week number in Python.

We will cover different approaches, including built-in modules, external libraries, and manual calculations.

So let’s dive in and learn how to get the week number in Python!

Python’s built-in datetime module provides functionalities to work with dates and times.

We can leverage this module to extract the week number from a given date.

Here’s a how you can get week number in python.

Example 1: How to get week number in Python?

import datetime

def get_week_number(date):
    return date.isocalendar()[1]

# Usage example:
current_date = datetime.date.today()
week_number = get_week_number(current_date)
print("Week number:", week_number)

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Output

In this method, we utilize the isocalendar() function, which returns a tuple containing the year, week number, and weekday for the specified date.

We extract the week number using the index [1] from the returned tuple.

The calendar module in Python provides various utilities for working with calendars, including week numbers.

Here’s how we can use it.

Example 2: How to get week number in Python?

import calendar
import datetime

def get_week_number(date):
    return date.strftime("%U")

# Usage example:
current_date = datetime.date.today()
week_number = get_week_number(current_date)
print("Week number:", week_number)

Output

In this approach, we use the strftime() function to format the date as a string using the “%U” directive.

The “%U” directive represents the week number of the year (Sunday as the first day of the week) as a decimal number (00-53).

The dateutil library is a powerful third-party library that extends Python’s datetime module with additional functionalities.

To use this library, you need to install it first using pip install python-dateutil.

Here’s an example of how to obtain the week number using dateutil.

Example 3: How to get week number in Python?

from dateutil import parser

def get_week_number(date):
    return date.isocalendar()[1]

# Usage example:
current_date = parser.parse("2023-05-17")
week_number = get_week_number(current_date)
print("Week number:", week_number)

Output

In this method, we make use of the isocalendar() function, similar to Method 1.

However, we utilize dateutil‘s parser.parse() function to convert a date string into a datetime object.

If you prefer a manual approach without relying on external modules, you can calculate the week number using basic arithmetic operations.

Here’s an example.

Example 4: How to get week number in Python?

import datetime

def get_week_number(date):
    first_day_of_year = datetime.date(date.year, 1, 1)
    days_passed = (date - first_day_of_year).days
    week_number = (days_passed // 7) + 1
    return week_number

# Usage example:
current_date = datetime.date.today()
week_number = get_week_number(current_date)
print("Week number:", week_number)

Output

In this method, we calculate the number of days that have passed between the given date and the first day of the year.

We then divide it by 7 to obtain the number of weeks passed, adding 1 to account for the first week.

In this blog post, we explored various methods to get the week number in Python. We covered built-in modules such as datetime and calendar libraries.

Additionally, we discussed a manual calculation approach.

Now you have a comprehensive understanding of different techniques to extract the week number from a given date.

Choose the method that best suits your needs and start incorporating it into your Python projects.

Happy coding!

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