Weekday trong Python

Python’s DateTime module offers a wide range of time-handling functions that make life a breeze. However, there’s no direct method to return a plain-English representation of a weekday name. Fortunately, there are several easy ways to get there.

Table of Contents

Getting the Date + Weekday

Before we take a look at getting the weekday name, let’s consider how Python’s datetime class gets a date and, subsequently, determines the day of the week for said date. There’s nothing fancy about it—but it pays to know where you’re starting.

from datetime import datetime

# Create datetime object
date = datetime.now[]
>>> 2021-02-07 15:30:46.665318

# Get the weekday value, as an integer
date.weekday[]
>>> 6

This code illustrates how far the datetime class will get you before you have to start getting creative.  Before we move on, there are two things worth noting:

• The weekday method assigns Monday the value 0
• Another method, the isoweekday, assigns Sunday the value of 1

Check out the official documentation for more info. Now, knowing how to get an integer representation of the weekday for a given datetime object, we can start scheming on how to produce a plain-English version. Below are three approaches ranked in order of dependencies.

Method 1: Do it Manually

# Define a list of weekday names
days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

# Index using weekday int value
days[date.weekday[]]

>>> Sunday

This approach offers the flexibility of being able to tweak weekday naming and order on-the-fly. Need to truncate the date names? Just edit the list. Need to start with Sunday? Just re-arrange it. Need to reverse the list for some strange reason? Just 

# Define a list of weekday names
days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

# Index using weekday int value
days[date.weekday[]]

>>> Sunday

1 it!

Pros:

• No added dependencies
• No added methods to remember
• Flexibility for change
• Explicit representation in code

Cons:

• More typing
• Not immediately resistant to duplication issues [i.e. using it across a project]
• The fear of typos

Method 2: Use Strftime

# Convert the integer to english representation
date.date[].strftime["%A"]

>>> Sunday

This method is, arguably, the most succinct. It’s a reasonable one-liner, doesn’t stray from the datetime class, and offers some flexibility once familiar with the .

Pros:

• No extra dependencies
• One-liner possible
• Semi-flexible
• No fear of typos
• Easy to integrate project-wide

Cons:

• Need to be familiar with

  # Define a list of weekday names
  days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']
  
  # Index using weekday int value
  days[date.weekday[]]
  
  >>> Sunday

  3 to change format

Method 3: The Calendar Module

import calendar

# Convert using calender's day_name method
calender.day_name[date.weekday[]]

>>> Sunday

This is really just a round-about way to achieve the same result as the first method. The added benefit here is that someone else manages the weekday list [not really a burden in this case.] The

# Define a list of weekday names
days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

# Index using weekday int value
days[date.weekday[]]

>>> Sunday

4 object is just a fancy list of all weekday names. Indexing into this object is the same as indexing into a manual list.

Pros:

• Built-in module
• Lightweight dependency
• Uses native Python syntax for indexing

Cons:

• Extra dependency
• The syntax could be simpler

Final Thoughts

When I was first learning to code, one of the biggest surprises to me was how complex managing time and dates can be. The subtle length differences in months, leap years, converting

# Define a list of weekday names
days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

# Index using weekday int value
days[date.weekday[]]

>>> Sunday

5 to

# Define a list of weekday names
days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']

# Index using weekday int value
days[date.weekday[]]

>>> Sunday

6—it seemed like wading into the deep end for what was such a peripheral task.