Skip to content

README.md

Latest commit

 

History

History
91 lines (62 loc) · 2.82 KB

README.md

File metadata and controls

91 lines (62 loc) · 2.82 KB
Raw

Standard Library Modules

Python includes a rich set of built-in modules (the Standard Library) that solve common programming problems out-of-the-box.

1. The os Module (Operating System)

Used for interacting with the operating system, navigating directories, and reading environment variables.

import os

print(os.getcwd())             # Get current working directory
print(os.listdir("."))         # List all files/folders in the current directory
os.makedirs("new_dir", exist_ok=True)  # Create a directory safely (no error if it exists)

2. The sys Module (System)

Used to access system-specific parameters and functions (like command-line arguments and Python interpreter versions).

import sys

print(sys.version)  # Prints current Python version details
print(sys.argv)     # List of command line arguments passed to the script

3. The random Module

Used to generate pseudo-random numbers, choose random items, or shuffle lists.

import random

print(random.randint(1, 10))  # Random integer between 1 and 10 (inclusive)

items = ["apple", "banana", "cherry"]
print(random.choice(items))   # Picks a random item from the list

random.shuffle(items)         # Shuffles the list in-place
print(items)

4. The collections Module

Provides specialized container data types to supplement Python's general-purpose built-ins.

Counter

A dict subclass for counting hashable objects.

from collections import Counter

words = ["apple", "banana", "apple", "cherry", "banana", "apple"]
count = Counter(words)
print(count)  # Output: Counter({'apple': 3, 'banana': 2, 'cherry': 1})
print(count.most_common(1))  # Output: [('apple', 3)]

defaultdict

A dict subclass that calls a factory function to supply missing values, avoiding KeyError.

from collections import defaultdict

# Creates a list for any new key automatically
grouped_data = defaultdict(list)
grouped_data["fruits"].append("apple")
print(grouped_data)  # Output: defaultdict(<class 'list'>, {'fruits': ['apple']})

5. Standard Modules Recap (Math, JSON, Datetime, Pathlib)

  • math: Math functions and constants (math.sqrt(), math.ceil(), math.floor(), math.pi).
  • json: Serializing and parsing JSON strings and files (json.loads(), json.dumps(), json.load(), json.dump()).
  • datetime: Date and time manipulation (datetime.datetime.now(), strftime()).
  • pathlib: Modern object-oriented path handling (Path("my_folder") / "file.txt").

Further Reading