1.1 Python
Every entry filed under Python and its subtopics.
What kind of help
What do these mean?
- Beginner
- You are new to this topic.
- Intermediate
- You use it, and want to get better.
- Advanced
- You know it well and need the details.
- Guided project
- Build something small from start to finish, step by step.
- Explains an idea
- Plain words on how something works and why.
- Step by step
- Numbered steps to get one task done.
- Cheat sheet
- Commands and options in a table, to look up fast.
- Fixes an error
- An error message, what it means, and how to solve it.
24 entries match these filters
- 0387 Install Python on Linux, macOS and Windows Install a current Python 3 with pip and venv on each desktop OS, check the version, and avoid the classic traps: python… Beginner · Step by step · Linux, macOS, Windows Article Environments & packages · Installing languages & tools 15 Oct 2026
- 0340 Build and run a small Python web app in a container Write a tiny Flask app, give it a Dockerfile, build the image, run it with a published port, make a change and… Beginner · Guided project · Linux, macOS, Windows Article Basics · Docker basics · Images & registries 15 Oct 2026
- 0282 What is a dependency? A dependency is another piece of software your program needs to work, such as a library it imports. Beginner · Explains an idea · Any system Article Environments & packages 15 Oct 2026
- 0283 What is a virtual environment? A virtual environment is a private folder of Python packages for one project, so different projects never clash. Beginner · Explains an idea · Any system Article Environments & packages 15 Oct 2026
- 0261 Build a Python command-line to-do app: from empty folder to installable command Create a small to-do tool in Python with argparse and JSON storage, test it with pytest and package it with pyproject.toml so… Beginner · Guided project · Any system Article Environments & packages · Files & automation · Testing 15 Oct 2026
- 0096 Flask (pallets/flask) A lightweight Python web framework for building websites and JSON APIs, with routing, request handling, and templates, and extensions for everything else. Any system Repo Python · Web frameworks 15 Oct 2026
- 0074 pandas basics: read a CSV, filter rows and summarize with groupby Load a CSV into a pandas DataFrame, inspect it, filter rows with conditions, and compute totals per group, with the SQL equivalent… Intermediate · Step by step · Any system Article Data analysis · Files & automation 15 Oct 2026
- 0075 CSV to JSON converter (Python, standard library) Convert any CSV file with a header row into a JSON array or JSON Lines. Handles quoted fields, a byte order mark,… Beginner · Step by step · Any system Script CSV & JSON · Files & automation 15 Oct 2026
- 0084 Tiny JSON echo server for testing HTTP clients A standard-library Python server that echoes back the method, path, query, headers, and body of every request, and can return any status… Intermediate · Step by step · Any system Script Files & automation · Making requests 15 Oct 2026
- 0073 Fix: json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0) Python's json module found nothing it could parse at the very first character. The input is usually empty, HTML, or already consumed.… Beginner · Fixes an error · Any system Article Common errors · CSV & JSON 15 Oct 2026
- 0010 Find duplicate files by content Scans folders and lists files with identical content, using file size first and SHA-256 hashes second. It is read-only and only reports… Intermediate · Step by step · Any system Script Files & automation 15 Oct 2026
- 0012 Requests: HTTP for humans Requests is the classic Python library for calling web APIs and downloading pages, with a simple API for GET and POST requests,… Any system Repo Files & automation · Making requests 15 Oct 2026
- 0005 Dataclasses in depth @dataclass writes __init__, __repr__ and __eq__ for classes that mainly hold data. Learn defaults, default_factory, frozen and ordered classes, __post_init__ validation, slots… Advanced · Explains an idea · Any system Article Basics 15 Oct 2026
- 0006 Testing with pytest: first tests, fixtures and parametrize pytest runs plain functions whose names start with test_ and reports every failing assert in detail. This guide covers setup, assertions, exceptions,… Intermediate · Step by step · Any system Article Testing 15 Oct 2026
- 0013 pytest pytest is the de facto standard test runner for Python: plain functions with assert, detailed failure reports, fixtures, parametrization and a large… Any system Repo Testing 15 Oct 2026
- 0007 Fix: ModuleNotFoundError: No module named ‘…’ Python cannot find a module you import. Usually the package was installed into a different interpreter or virtual environment than the one… Beginner · Fixes an error · Any system Article Common errors · Environments & packages 15 Oct 2026
- 0015 Ruff: Python linter and formatter Ruff is a fast Python linter and code formatter written in Rust. It catches bugs such as undefined names and unused imports… Any system Repo Common errors · Testing 15 Oct 2026
- 0014 uv: Python package and project manager uv is a very fast Python package and project manager written in Rust. It replaces pip, venv and related tools, manages lock… Any system Repo Environments & packages 15 Oct 2026
- 0008 Fix: TypeError: ‘NoneType’ object is not subscriptable You used [ ] on a value that is None. Something you expected to return a list, dict or match returned nothing.… Beginner · Fixes an error · Any system Article Common errors 15 Oct 2026
- 0004 Logging instead of print The logging module gives every message a level, a timestamp and a destination you can change without editing code. It is the… Intermediate · Explains an idea · Any system Article Files & automation 15 Oct 2026
- 0009 CSV to JSON converter A small command-line tool that turns a CSV file into a JSON array of objects, with optional number detection, custom delimiters and… Beginner · Step by step · Any system Script CSV & JSON · Files & automation 15 Oct 2026
- 0002 Python cheat sheet: strings, lists, dicts and f-strings The everyday methods for text, lists and dictionaries, plus f-string formatting and comprehensions, each with a one-line example you can paste into… Beginner · Cheat sheet · Any system Article Basics 15 Oct 2026
- 0001 Virtual environments with venv A virtual environment is a private folder of Python packages for one project, so projects never fight over versions. Create one with… Beginner · Explains an idea · Any system Article Environments & packages 15 Oct 2026
- 0003 pathlib cheat sheet: files and folders in Python pathlib.Path is the modern way to build paths, read and write files, and list or search folders in Python. This page lists… Beginner · Cheat sheet · Any system Article Files & automation 15 Oct 2026