5 Best Ways to Retrieve Weekday Names in Python Using datetime

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💡 Problem Formulation: When working with dates in Python, you may need to find out the day of the week for a specific date. The problem is to transform a date object into a human-readable weekday name (e.g., Monday, Tuesday). For instance, given the input date ‘2021-11-01’, the expected output is ‘Monday’.

Method 1: Using the datetime Module with strftime()

The datetime module in Python provides various classes for manipulating dates and times. One of these classes, datetime.datetime, has a method called strftime() which can be used to format date objects into readable strings, including weekday names.

Here’s an example:

from datetime import datetime

date_object = datetime(2021, 11, 1)
weekday_name = date_object.strftime('%A')

print(weekday_name)

Output: Monday

This code snippet first imports the datetime class from the datetime module. A date object representing November 1st, 2021, is created. The strftime() method with the format code '%A' converts this date object into the full name of the weekday.

Method 2: Using the calendar Module

The calendar module provides functions related to the calendar, including functions to get the weekday name. The day_name attribute holds the names of the weekdays that can be indexed using the week day number (0 for Monday and so on).

Here’s an example:

import calendar
from datetime import datetime

date_object = datetime(2021, 11, 1)
weekday_number = date_object.weekday()
weekday_name = calendar.day_name[weekday_number]

print(weekday_name)

Output: Monday

In this example, we first import the calendar module along with the datetime class from the datetime module. We create a date object for November 1st, 2021, and obtain the corresponding weekday number using the weekday() method. We then use this number as an index to find the weekday name in the calendar.day_name array.

Method 3: Using Locale’s format() Function

Locale settings provide localization capabilities for formatting dates. The format() function in the locale module can be used to display the weekday name based on the system’s locale settings.

Here’s an example:

import locale
from datetime import datetime
locale.setlocale(locale.LC_TIME, 'en_US.UTF-8')

date_object = datetime(2021, 11, 1)
weekday_name = date_object.strftime('%A')

print(weekday_name)

Output: Monday

The locale module is first imported and the locale for time is set to English (United States). The strftime() method is then used as before to format the date object into the full name of the weekday in accordance with the set locale. This approach allows for localized weekday names if needed.

Method 4: Using pandas day_name() Function

Pandas is a powerful data analysis and manipulation library in Python. It also provides methods to work with dates in a DataFrame. One such method, day_name(), returns the name of the day of the week.

Here’s an example:

import pandas as pd

date_object = pd.Timestamp('2021-11-01')
weekday_name = date_object.day_name()

print(weekday_name)

Output: Monday

This code snippet creates a Timestamp object in pandas for November 1st, 2021. The day_name() function is then called on this Timestamp object, which directly returns the name of the weekday. This method is particularly handy when dealing with time series data in pandas.

Bonus One-Liner Method 5: Using a Lambda Function

For those looking for a quick one-liner, a lambda function can be used in combination with the datetime module. This is useful for inline operations or when defining a function is not necessary.

Here’s an example:

from datetime import datetime

weekday_name = (lambda d: d.strftime('%A'))(datetime(2021, 11, 1))

print(weekday_name)

Output: Monday

Here we define a lambda function that takes a date object and calls the strftime('%A') method on it to get the weekday name. The lambda function is immediately invoked with a newly created date object for November 1st, 2021. While compact, this approach can reduce readability.

Summary/Discussion

  • Method 1: datetime.strftime(). Very common and straightforward. Limited to Python’s datetime objects.
  • Method 2: calendar.day_name. Relies on the built-in calendar module. Slightly more verbose but powerful for calendar-related operations.
  • Method 3: Locale’s format(). Suitable for localizing the weekday names. Requires understanding of locale settings.
  • Method 4: pandas day_name(). Best when working within the pandas ecosystem, especially with DataFrame objects. Overkill for simple tasks if pandas is not already in use.
  • Method 5: Lambda Function. Quick and concise. Best for minimal inline uses. Can hinder code clarity if overused.