Python Code
Samples
Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
How to Generate Project Statistics Including Lines of Code and Complexity in Python
Walk through a Python script that scans a project directory for Python files, counts lines of code excluding blanks and comments, and estimates cyclomatic complexity by counting decision keywords.
import os
from pathlib import Path
def count_lines_of_code(filepath):
"""Counts lines of code in a Python file, excluding blank lines and comments."""
try:
with open(filepath, 'r') as f:
lines = f.readlines()
code_lines = [line for line in lines if line.strip() and not line.strip()…How to Generate Thumbnails While Maintaining Aspect Ratio in Python
Resize images to fit within maximum dimensions while preserving the original aspect ratio using Pillow (PIL).
from PIL import Image
def thumbnail_with_aspect_ratio(image_path, output_path, max_width, max_height):
with Image.open(image_path) as img:
# Get original dimensions
width, height = img.size
# Calculate scaling ratio to fit within max dimensions
ratio = min(max_width / width, max_h…How to Generate a Dependency Graph for Python Projects
This script walks through a Python project directory, parses each .py file's imports, and prints a dependency graph showing which modules depend on which other modules.
import os
import ast
from pathlib import Path
from collections import defaultdict
def get_imports(filepath):
with open(filepath) as f:
try:
tree = ast.parse(f.read())
except SyntaxError:
return []
imports = []
for node in ast.walk(tree):
if isinstance(node, …How to Generate a QR Code in Python
Generate a QR code image from a URL string using the qrcode library and save it as a PNG file.
import qrcode
# Data to encode
data = "https://www.example.com"
# Create QR code instance
qr = qrcode.QRCode(
version=1,
error_correction=qrcode.constants.ERROR_CORRECT_L,
box_size=10,
border=4,
)
# Add data to QR code
qr.add_data(data)
qr.make(fit=True)
# Create an image from the QR code
img = qr.…How to Generate a cloud-init User Data Mock in Python
Generate a cloud-init user data mock for a VM using a dataclass and JSON in Python.
import json
from dataclasses import dataclass, asdict
@dataclass
class VMConfig:
hostname: str
cpus: int
memory_mb: int
ssh_key: str
def generate_cloud_init_mock(config: VMConfig) -> str:
"""Build a cloud-init user-data mock for a VM."""
user_data = {
"hostname": config.hostname,
…How to Generate an Inventory CSV of Installed pip Packages in Python
This script uses subprocess and csv to list all installed pip packages and write their names and versions into a CSV inventory file.
import subprocess
import csv
def get_installed_packages():
"""Return a list of (name, version) tuples for installed pip packages."""
result = subprocess.run(
["pip", "list", "--format=freeze"],
capture_output=True,
text=True,
check=True
)
packages = []
for line in r…How to generate an htpasswd bcrypt entry in Python
Create a mock htpasswd file entry with a bcrypt-hashed password for a given username using a simple Python script.
import bcrypt
def mock_htpasswd_entry(username, password):
salt = bcrypt.gensalt(rounds=12)
hashed = bcrypt.hashpw(password.encode(), salt).decode()
return f"{username}:{hashed}"
if __name__ == "__main__":
entry = mock_htpasswd_entry("demo_user", "s3cretP@ss")
print(entry)How to generate website performance reports from HTTP requests in Python
Measure and report website load time, status code, and content size using Python's standard library.
import urllib.request
import time
def measure_website_load_time(url):
"""Measures total loading time of a website."""
start_time = time.time()
try:
with urllib.request.urlopen(url, timeout=10) as response:
content = response.read()
status_code = response.status
…Add a UUID Surrogate Key to Each Row in a CSV with Python
Generate a unique UUID string for every row in a CSV file using the standard-library uuid and csv modules.
import uuid
import csv
def add_surrogate_key(filename):
with open(filename, newline='') as f_in:
reader = csv.DictReader(f_in)
rows = list(reader)
for row in rows:
row['surrogate_key'] = str(uuid.uuid4())
with open(filename, 'w', newline='') as f_out:
writer = csv.DictWri…Generate a Deterministic Hash for Deduplication in Python
Create a stable SHA-256 fingerprint from nested data and file contents to deduplicate records in a data pipeline.
import hashlib
import json
from pathlib import Path
def natural_key_hash(data, salt=""):
"""
Generate a deterministic fingerprint from raw data (dict/list/str).
Uses JSON canonical-ish serialization with sorted keys and SHA-256.
"""
canonical = json.dumps(data, sort_keys=True, separators=(",", ":"…Generate a Mock CDC Changelog in Python
Simulate a CDC changelog with INSERT, UPDATE, and DELETE operations, timestamps, and record snapshots for testing data pipelines.
import json
from datetime import datetime, timedelta
def generate_mock_changelog(records, operations=("INSERT", "UPDATE", "DELETE")):
"""Simulate a CDC changelog from a list of record snapshots."""
base_time = datetime(2025, 1, 1, 8, 0, 0)
changelog = []
for idx, record in enumerate(records):
…How to create a dated snapshot path for a dataset in Python
Generate a versioned directory path combining a base directory, dataset name, and today's date, ready for creating snapshots in data pipelines.
import datetime
import os
from pathlib import Path
def snapshot_path(base_dir: str, dataset_name: str) -> Path:
"""Return a dated snapshot path for a dataset under a base directory."""
today = datetime.date.today().isoformat()
return Path(base_dir) / dataset_name / today
if __name__ == "__main__":
…Generate CHANGELOG from Conventional Commits in Python
Parse your git log for conventional commits (feat, fix) and produce a simple Markdown CHANGELOG with grouped features and bug fixes.
import subprocess
import re
import sys
from collections import OrderedDict
CONVENTIONAL_COMMIT = re.compile(
r"^(?P<type>feat|fix|chore|docs|refactor|perf|test|build|ci|style)(?:\((?P<scope>[^)]+)\))?: (?P<description>.+)"
)
def get_git_log():
return subprocess.run(
["git", "log", "--format=%s"],
…Generate Release Notes Markdown from PR Titles in Python
Generate structured Markdown release notes from a list of pull request titles using conventional commit types.
import json
from datetime import datetime, timezone
PRS = [
{"title": "feat: add user login", "number": 12, "merged_at": "2025-01-10"},
{"title": "fix: resolve payment timeout", "number": 13, "merged_at": "2025-01-11"},
{"title": "chore: bump dependencies", "number": 14, "merged_at": "2025-01-12"},
{"…How to Format Git Patch Series as an MBOX File in Python
Generate a patch-series mbox file from commit metadata with numbered [PATCH nnn/nnn] subjects and a Git-style footer.
import re
from pathlib import Path
def format_patch_series_mbox(commits, output_path="series.mbox"):
entries = []
for idx, commit in enumerate(commits, start=1):
subject = commit["subject"]
author = commit["author"]
email = commit["email"]
date = commit["date"]
body = …How to Generate Git LFS Extension Patterns in Python
This script builds mock Git LFS file patterns for common geospatial extensions and filters them based on compression suffixes.
import itertools
import re
LFS_EXTENSIONS = {".csv", ".geojson", ".tif", ".shp", ".gpkg"}
def build_mock_lfs_pattern(base_name="data_usgs_lidar"):
patterns = []
for ext in sorted(LFS_EXTENSIONS):
for variant in (("", ".lz4"), (".compressed",), (".b", ".a"), ("_v1", ".zip")):
full_pattern …How to Generate Release Notes from Git Commit Messages in Python
This script fetches recent Git commit messages using conventional commit prefixes (feat, fix, etc.), categorizes them, and prints formatted release notes with today's date.
import subprocess
import re
from datetime import datetime
def get_git_log(since_tag="HEAD~10", format_str="%s"):
"""Retrieve commit messages from git log."""
try:
result = subprocess.run(
["git", "log", f"--since={since_tag}", f"--format={format_str}"],
capture_output=True,
…How to generate and parse an interactive rebase TODO list in Python
Generate a Git interactive rebase TODO list from commit data and parse it back into structured records.
import re
from collections import namedtuple
Commit = namedtuple("Commit", ["hash", "subject"])
def generate_rebase_todo(commits, action="pick"):
todo_lines = []
for i, commit in enumerate(commits):
if i == 0 and action == "reword":
todo_lines.append(f"reword {commit.hash} {commit.subject…Generate Mock CloudFormation Stack Events in Python
Generate a list of mock AWS CloudFormation stack events with random resources, statuses, and timestamps, and print them as JSON.
import json
import random
from datetime import datetime, timedelta
def generate_mock_stack_events(stack_name="MyTestStack", num_events=10):
"""Generate a list of mock CloudFormation stack events."""
resources = [
("AWS::S3::Bucket", "MyBucket"),
("AWS::EC2::Instance", "MyInstance"),
("…Generate a Mock Presigned URL in Python with HMAC
Build a mock AWS S3 presigned URL using an HMAC-SHA256 signature, mimicking the core SigV4 pattern without cloud SDK dependencies.
import hashlib
import hmac
import time
import base64
def generate_presigned_url_mock(secret_key, bucket, object_key, expires_in=3600):
# Build the canonical request string (simplified AWS SigV4 style)
timestamp = str(int(time.time()))
expiry = str(int(time.time()) + expires_in)
payload = f"GET\n/{buck…Generate an Idempotency-Key header mock with UUID in Python
This code provides a mock idempotency service that generates a UUID-based Idempotency-Key header token and validates it, useful for simulating production API behavior in tests.
import uuid
class MockIdempotencyService:
def __init__(self):
self._tokens = {}
def get_token(self, header_name="Idempotency-Key"):
token = str(uuid.uuid4())
self._tokens[header_name] = token
return token
def validate(self, header_name="Idempotency-Key"):
return s…How to Generate a Mock EKS Kubeconfig in Python
Generate a minimal kubeconfig dict with a mock EKS cluster entry and dump it to YAML using PyYAML.
import yaml
from pathlib import Path
def mock_eks_kubeconfig(cluster_name: str) -> dict:
"""Return a minimal kubeconfig dict with a mock EKS cluster entry."""
return {
"apiVersion": "v1",
"kind": "Config",
"clusters": [
{
"name": f"arn:aws:eks:us-east-1:123…Pick a Random Region with Mock Carbon Intensity in Python
Selects a random region from a list and generates a mock carbon intensity value using Python's random module.
import random
def pick_region_intensity(regions, seed=42):
random.seed(seed)
selected = random.choice(regions)
intensity = random.randint(1, 10)
return selected, intensity
if __name__ == "__main__":
regions = ["North", "South", "East", "West"]
selected, intensity = pick_region_intensity(regio…How to Create a Mock Virtualenv with an Activation Script in Python
Create a mock virtualenv directory with a generated bash activation script using Python's standard library.
import os
import subprocess
import sys
from pathlib import Path
def mock_virtualenv(name: str = "myenv") -> Path:
"""Create a mock virtualenv directory and activation script."""
env_dir = Path(name)
env_dir.mkdir(exist_ok=True)
(env_dir / "bin").mkdir(exist_ok=True)
activate_script = f"""#!/bin/…Browse by section
Each section groups closely related Python snippets.
Guide: free Python code samples library
Copy-ready Python snippets for learners and developers
PythonSkillset code samples are short, focused examples organised by topic and difficulty. Every snippet is server-rendered HTML — readable by search engines and easy to copy. Open any sample, read the notes, copy the code, then press Try in editor to run it in the browser with Pyodide.
How to use this library
- Pick a topic section — strings, lists, files, functions, and more
- Open a sample, read How it works, and copy the code block
- Run it in the IDE, tweak values, then take a related quiz or tutorial lesson
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.