Master Python Essentials: Sets, Calendars, Enums, and More

01. Sets

Developers often forget that Python has a built‑in set type, which stores an unordered collection of unique elements. Mastering sets can simplify many tasks, such as extracting unique letters from a word.

myword = "NanananaBatman"
set(myword)  # {'N', 'm', 'n', 'B', 'a', 't'}

Sets also make it easy to obtain a list of unique items from another list.

mylist = ["a", "b", "c", "c"]
myset = set(mylist)          # {'a', 'b', 'c'}
for element in myset:
    print(element)
mynewlist = list(myset)      # ['a', 'b', 'c']

Note that the order of elements may change when converting between list and set.

02. Calendar

When working with dates, you often need to know how many days a month contains or what weekday a month starts on. The calendar module provides convenient functions for these tasks.

import calendar
calendar.monthrange(2020, 12)   # (1, 31)  # weekday, number of days
calendar.monthrange(2024, 2)    # (3, 29)  # leap year handling

You can map the returned weekday index to a name:

weekdays = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]
weekday_index, days = calendar.monthrange(2024, 2)
print(weekdays[weekday_index])  # Thursday

The module also offers helpers for leap‑year checks:

calendar.isleap(2024)      # True
calendar.leapdays(2020, 2026)  # 2

03. Enumerate with a Start Index

The enumerate function can accept a second argument to specify the starting index.

mylist = ['a', 'b', 'd', 'c', 'g', 'e']
for i, item in enumerate(mylist, 16):
    print(i, item)
# Output: 16 a, 17 b, 18 d, 19 c, 20 g, 21 e

04. Clean If‑Else Logic Using Enums

For many conditions, mapping status values to handler functions via an Enum makes the code cleaner and more maintainable.

from enum import IntEnum
class StatusE(IntEnum):
    OPEN = 1
    IN_PROGRESS = 2
    CLOSED = 3

def handle_open_status():
    print('Handling open status')

def handle_in_progress_status():
    print('Handling in‑progress status')

def handle_closed_status():
    print('Handling closed status')

handlers = {
    StatusE.OPEN.value: handle_open_status,
    StatusE.IN_PROGRESS.value: handle_in_progress_status,
    StatusE.CLOSED.value: handle_closed_status,
}

def handle_status_change(status):
    if status not in handlers:
        raise Exception(f'No handler for status: {status}')
    handlers[status]()

handle_status_change(StatusE.OPEN.value)   # Handling open status

05. The Enum Module

The enum module provides Enum and IntEnum for defining symbolic constants.

from enum import Enum, IntEnum
class MyEnum(Enum):
    FIRST = "first"
    SECOND = "second"
    THIRD = "third"

class MyIntEnum(IntEnum):
    ONE = 1
    TWO = 2
    THREE = 3

print(MyEnum.FIRST.value)   # 'first'
print(MyIntEnum.ONE == 1)   # True

Enums are especially useful in medium‑sized codebases for managing constants and can be integrated with Django choices.

06. iPython

iPython is an enhanced interactive Python shell. Install it with pip and start using it for richer command‑line experiences.

pip install ipython
# After launching, you will see a prompt like:
In [1]:

iPython supports system commands, tab completion, and command history, making it a valuable tool for rapid experimentation.