7 "Useless" Python Standard Library Functions You Should Know

These seemingly obscure Python functions from the standard library can be surprisingly useful for various programming tasks. This article explores seven such functions, demonstrating their practical applications with code examples.

1. `textwrap.dedent()` - Cleaning Multi-line Strings

This function is invaluable for tidying up multi-line strings that have unwanted leading whitespace due to indentation in the source code. It removes common leading whitespace from each line, ensuring clean and consistent string formatting.

Example:

import textwrap

def my_function():
    description = textwrap.dedent("""
        This is a multi-line string
        that will have consistent indentation
        regardless of how it's indented in the code.
        Pretty neat, right?
    """).strip()
    return description

print(my_function())

Output:

This is a multi-line string
that will have consistent indentation
regardless of how it's indented in the code.
Pretty neat, right?

2. `difflib.get_close_matches()` - Fuzzy String Matching

For scenarios requiring fuzzy string matching, such as implementing a "did you mean?" feature or finding similar strings, difflib.get_close_matches() is the go-to function. It returns a list of the best "close" matches to a query string from a given sequence.

Example 1:

import difflib

words = ["python", "javascript", "typescript", "ruby", "golang"]
search = "pythn"

matches = difflib.get_close_matches(search, words, n=3, cutoff=0.6)
print(f"Did you mean: {matches}")

Output:

Did you mean: ['python']

Example 2:

search = "typescript"
matches = difflib.get_close_matches(search, words)
print(f"Matches: {matches}")

Output:

['typescript', 'javascript']

This function is particularly useful for command-line tools and search functionalities where handling typos is essential.

3. `uuid.uuid4()` - Generating Unique IDs

When unique identifiers are needed without the complexity of database management or the risk of collisions, the uuid module provides a solution. uuid.uuid4() generates a random UUID (Universally Unique Identifier) that is practically guaranteed to be unique.

Example:

import uuid

# Generate a random UUID
random_id = uuid.uuid4()
print(f"Unique ID: {random_id}")

# Use as string for filenames, database keys, etc.
filename = f"document-{uuid.uuid4()}.pdf"
print(filename)

Output:

Unique ID: fc4c6638-9707-437b-83a1-76206b5f7191
filename = document-b5ccbe7a-fad9-4611-8163-be1015c634b9.pdf

UUIDs are ideal for generating unique IDs for files, database entries, or any situation requiring guaranteed uniqueness.

4. `shutil.get_terminal_size()` - Responsive CLI Applications

To create command-line applications that adapt to the user's terminal dimensions, shutil.get_terminal_size() is essential. It retrieves the current terminal size, allowing for dynamic layout adjustments.

Example:

import shutil

columns, rows = shutil.get_terminal_size()
print(f"Your terminal is {columns} columns wide and {rows} rows tall")

# Create a horizontal divider that fits perfectly
print("-" * columns)

Output:

Your terminal is 80 columns wide and 24 rows tall
--------------------------------------------------------------------------------

This function enables the creation of responsive CLI interfaces.

5. `itertools.groupby()` - Grouping Data Efficiently

itertools.groupby() provides an efficient way to group data based on a key without the overhead of creating dictionaries. It's crucial to sort the data by the grouping key first for groupby to function correctly.

Example:

from itertools import groupby
from operator import itemgetter

employees = [
    ("Alice", "Engineering"),
    ("Bob", "Marketing"),
    ("Charlie", "Engineering"),
    ("Diana", "HR"),
    ("Evan", "Marketing"),
]

employees.sort(key=itemgetter(1))

for department, group in groupby(employees, key=itemgetter(1)):
    print(f"\n{department} Department:")
    for name, _ in group:
        print(f"  - {name}")

Output:


Engineering Department:
  - Alice
  - Charlie

HR Department:
  - Diana

Marketing Department:
  - Bob
  - Evan

6. `collections.ChainMap` - Merging Dictionaries

collections.ChainMap is a useful class for managing multiple dictionaries. It allows you to search through them in order without the need for merging, effectively creating a single, updated view of the dictionaries.

Example:

from collections import ChainMap

defaults = {"theme": "dark", "language": "en", "timeout": 30}
user_settings = {"theme": "light"}
session_settings = {"timeout": 60}

settings = ChainMap(session_settings, user_settings, defaults)

print(settings["theme"])
print(settings["language"])
print(settings["timeout"])

Output:

light
en
60

This demonstrates how settings from different sources can be prioritized.

7. `os.path.commonpath()` - Finding Shared Directory Paths

To determine the longest common directory path among a list of file paths, os.path.commonpath() is the ideal function. It's particularly useful for tasks involving file organization and path manipulation.

Example:

import os.path

paths = [
    "/home/user/documents/work/report.pdf",
    "/home/user/documents/personal/taxes.xlsx",
    "/home/user/documents/work/presentation.pptx"
]

common = os.path.commonpath(paths)
print(f"Common directory: {common}")

Output:

Common directory: /home/user/documents

Conclusion:

Python's standard library is a treasure trove of specialized functions that can simplify complex tasks. By exploring these lesser-known utilities, developers can write more efficient and elegant code. Always consider checking the standard library for solutions before implementing custom logic.

Author Bio:

Bala Priya C is a developer and technical writer from India, passionate about the intersection of math, programming, data science, and content creation. Her expertise spans DevOps, data science, and natural language processing. She actively shares her knowledge through tutorials, guides, and opinion pieces, aiming to contribute to the developer community.

7 "Useless" Python Standard Library Functions You Should Know