Python Code
Samples
Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
Python Script to Rotate a Leaked API Key
A checklist-driven Python script that scans a codebase for a leaked API key, replaces it with a new one, and prints a step-by-step rotation checklist.
#!/usr/bin/env python3
"""Checklist for rotating a leaked API key across a codebase."""
import re
from pathlib import Path
CHECKLIST = [
"Identify all files containing the leaked key",
"Generate a new key with sufficient entropy",
"Update the secret storage/CI environment variables",
"Replace the ol…Show Blame Line Author with subprocess in Python
This Python script runs git blame --line-porcelain via subprocess and counts how many lines each author owns in a file.
import subprocess
from collections import Counter
def get_blame_authors(file_path):
"""Extract author names from git blame output using subprocess."""
result = subprocess.run(
["git", "blame", "--line-porcelain", file_path],
capture_output=True,
text=True,
check=True,
)
…Create a Cloud Storage Helper Class in Python
Build a simple local file-based helper class that mimics cloud storage operations like save, load, and list JSON objects.
import datetime
import json
from pathlib import Path
class CloudDataHelper:
"""Simple helper for reading/writing JSON files in a cloud-style folder."""
def __init__(self, base_dir: str = "cloud_storage"):
self.base_dir = Path(base_dir)
self.base_dir.mkdir(exist_ok=True)
def save_json(se…Create a Data Helper Class for Beginners in Python
A simple Python class to read and write JSON and CSV files from a local directory, ideal for automating data workflows in cloud environments.
import json
from pathlib import Path
class DataHelper:
"""Simple helper for reading and writing common data files."""
def __init__(self, directory="data"):
self.directory = Path(directory)
self.directory.mkdir(exist_ok=True)
def save_json(self, filename, data):
filepath =…How to Build a Multi-Cloud Config Loader with Provider Switching in Python
Load cloud provider configurations (AWS, Azure, GCP) from JSON files using a provider dispatch pattern in Python.
import json
from pathlib import Path
from dataclasses import dataclass
from typing import Dict, Any
@dataclass
class CloudConfig:
provider: str
region: str
settings: Dict[str, Any]
class ConfigLoader:
def __init__(self, config_dir: str = "configs"):
self.config_dir = Path(config_dir)
…How to Check an SCP Deny List in Python
Load a JSON SCP policy file, extract the deny_list, and check if a target ARN is denied.
import json
from pathlib import Path
def evaluate_scp_deny_list(policy_path: Path, target_path: str) -> bool:
policy = json.loads(policy_path.read_text())
deny_list = policy.get("deny_list", [])
return target_path in deny_list
if __name__ == "__main__":
policy_file = Path("scp_policy.json")
pol…How to Create a JSON Data Helper in Python
A beginner-friendly DataHelper class that safely reads and writes JSON files with timestamps to a local data directory.
from datetime import datetime
from pathlib import Path
import json
class DataHelper:
"""Simple helper for reading/writing JSON files safely."""
def __init__(self, base_dir="data"):
self.base_dir = Path(base_dir)
self.base_dir.mkdir(exist_ok=True)
def save(self, filename, data):
…How to Design a Cloud Data Helper Class in Python
A beginner-friendly Python helper class that saves, loads, and aggregates JSON records locally, simulating cloud-style data handling.
import json
from pathlib import Path
from datetime import datetime
class CloudDataHelper:
"""Beginner-friendly helper for working with cloud-based JSON data."""
def __init__(self, base_dir="cloud_data"):
self.base_dir = Path(base_dir)
self.base_dir.mkdir(exist_ok=True)
def save_record(s…How to Mock CloudFront Invalidation Paths in Python
Build a sorted, deduplicated list of CloudFront invalidation paths from a set of file paths, adding implicit index.html entries.
import argparse
def build_invalidation_paths(files, include_index=True):
"""
Create CloudFront invalidation paths from a list of files.
Converts file names to root-relative paths and optionally adds /index.html.
"""
paths = []
for f in files:
f = f.strip()
if not f:
…How to mock boto3 S3 upload file wrapper in Python
Wrap an S3 put_object call in a testable function that returns metadata, and mock boto3 to verify the upload without touching AWS.
import boto3
import io
def upload_file_to_s3(file_obj, bucket, key, object_metadata=None):
"""Upload a file-like object to S3 and return a metadata dict."""
s3 = boto3.client("s3")
content = file_obj.read()
s3.put_object(
Bucket=bucket,
Key=key,
Body=content,
Metadata=…Mock S3, GCS, and Azure storage with a Python abstract interface
Define an abstract Storage interface and implement a local, filesystem-backed mock so S3, GCS, and Azure code can be tested without cloud dependencies.
from abc import ABC, abstractmethod
from pathlib import Path
class Storage(ABC):
@abstractmethod
def put(self, name: str, data: bytes) -> None:
pass
@abstractmethod
def get(self, name: str) -> bytes:
pass
class LocalStorage(Storage):
def __init__(self, base_dir: str = "mock_sto…Data Conversion Helper Functions in Python
A set of beginner-friendly helper functions to convert between JSON strings and Python data, parse dates, and read/write files using pathlib.
from datetime import datetime
from pathlib import Path
import json
def to_json(data, indent=2):
"""Convert Python data to pretty-printed JSON string."""
return json.dumps(data, indent=indent, default=str)
def from_json(json_string):
"""Parse JSON string back into Python data."""
return json.loads(jso…How to Export a Conda Environment YAML File in Python
Generate a mock conda environment YAML export with a reusable Python function and the PyYAML library.
import yaml
def conda_env_mock(name="demo_env", channels=None, packages=None):
channels = channels or ["defaults"]
packages = packages or [
"python=3.11",
"pip",
"numpy=1.24.3",
"pandas=2.0.3",
]
env_dict = {
"name": name,
"channels": channels,
…How to Format Data with Python's datetime and JSON Helpers
A beginner-friendly set of helper functions to format dates and safely read/write JSON files in Python.
from datetime import datetime
from pathlib import Path
import json
def format_today(pattern: str = "%Y-%m-%d") -> str:
"""Return today's date formatted with the given pattern."""
return datetime.now().strftime(pattern)
def load_json(file_path: str) -> dict:
"""Read and parse a JSON file safely."""
…How to Generate a Mock devcontainer.json Config in Python
Build a reproducible devcontainer.json file with Python, composing name, image, extensions, forwarded ports, and a post-create command as a dict.
import json
from pathlib import Path
def create_devcontainer_config(
image: str = "mcr.microsoft.com/devcontainers/python:3.11",
name: str = "python-dev-container",
ports: list[int] | None = None,
post_create: str | None = None,
) -> dict:
config = {
"name": name,
"image": image,
…How to List Pre-commit Hooks from YAML Config in Python
Parse a .pre-commit-config.yaml file with PyYAML and print every hook ID paired with its source repository.
import yaml
pre_commit_config = """
repos:
- repo: https://github.com/pre-commit/pre-commit-hooks
rev: v4.5.0
hooks:
- id: trailing-whitespace
- id: end-of-file-fixer
- id: check-yaml
- repo: https://github.com/psf/black
rev: 23.11.0
hooks:
- id: black
"""
def list_hooks(c…How to Load and Inspect CSV Data with a Dataclass Helper in Python
This code defines a DataHelper dataclass that reads a CSV file into a list of dictionaries and prints basic dataset information.
from pathlib import Path
from dataclasses import dataclass
from typing import Any
@dataclass
class DataHelper:
"""Simple helper for loading and inspecting CSV data."""
filepath: Path
def load_csv(self, *, delimiter: str = ",") -> list[dict[str, Any]]:
"""Read CSV into a list of dictionaries."""
…How to Load and Inspect Data Files in Python
A beginner-friendly DataLoader dataclass that loads JSON or text files and provides methods to preview and inspect the data.
from dataclasses import dataclass, field
from pathlib import Path
import json
from typing import Any, Dict, List
@dataclass
class DataLoader:
"""Simple helper to load and inspect data files for beginners."""
path: Path
data: Any = field(init=False, default=None)
def __post_init__(self) -> None:
…How to Load and Save CSV and JSON Files in Python
A beginner-friendly data helper that loads or saves CSV and JSON files using only the Python standard library, with automatic format detection from the file extension.
from pathlib import Path
import json
import csv
def load_data(file_path):
"""Load CSV or JSON data from disk based on file extension."""
path = Path(file_path)
if path.suffix == ".json":
with path.open() as f:
return json.load(f)
elif path.suffix == ".csv":
with path.open(…How to Load envrc Files in Python
Parse and apply direnv-style envrc files to the current environment, with proper handling of variables, comments, and quotes.
import os
import tempfile
from pathlib import Path
from unittest.mock import patch
def load_envrc(envrc_path):
"""Parse an envrc-style file and apply it to the current environment."""
env_changes = {}
with open(envrc_path, "r") as f:
for line in f:
line = line.strip()
if l…How to Mock Twine Upload to TestPyPI in Python
Simulate a twine upload to TestPyPI with a dry-run mock function that validates distribution files and prints the intended upload action without any network call.
import subprocess
import sys
# Mock twine upload to TestPyPI using subprocess dry-run
def mock_twine_upload(dist_file: str, repo_url: str = "https://test.pypi.org/legacy/") -> None:
"""Simulate twine upload by checking dist file and printing intended action."""
if not dist_file.endswith((".whl", ".tar.gz")):
…How to Mock a Fast uv pip sync in Python
Simulate a fast uv pip sync by mocking file operations and subprocess calls to test dependency installation workflows.
import os
import shutil
import subprocess
import sys
import tempfile
from pathlib import Path
def uv_pip_sync_fast_install_mock(requirements_text: str) -> dict:
"""Simulate a fast uv pip sync by mocking file operations and subprocess calls."""
mock_dir = Path(tempfile.mkdtemp(prefix="uv_mock_"))
req_lines…How to Mock a pyenv Local Version File in Python
Read and write a mock .python-version file using the pathlib module and tempfile for isolated testing.
import json
import tempfile
from pathlib import Path
def read_pyenv_local(directory: Path) -> str:
"""Read the .python-version file in the given directory."""
version_file = directory / ".python-version"
if not version_file.exists():
return "no-version-file"
return version_file.read_text().st…How to Parse Taskfile YAML in Python
Load a Taskfile.yaml with PyYAML and simulate task execution by returning each task's commands.
import yaml
from pathlib import Path
def load_taskfile(taskfile_path: str) -> dict:
"""Load and parse a Taskfile.yaml file into a dict."""
data = Path(taskfile_path).read_text()
return yaml.safe_load(data)
def run_task(taskfile: dict, task_name: str) -> dict:
"""Simulate running a task by returning i…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.