Python ยท Chapter 25 of 45
Packages & pip
A PACKAGE is a folder of modules with an `__init__.py`. Third-party packages are installed from the Python Package Index (PyPI) using `pip`.
Examples: `requests`, `numpy`, `pandas`, `flask`.
Installing
Run `pip install package` in your terminal. Use `pip install -r requirements.txt` to install from a list file.
requirements.txt
A plain text file listing dependencies (one per line, optionally pinned to a version). Commit it to version control.
Example 1 (bash)
pip install requests
python -c "import requests; print(requests.get('https://api.github.com').status_code)"Output
200Install a package then use it.
Example 2 (text)
requests>=2.31
numpy
pandas==2.2.*A typical requirements.txt file.
Key points
- `pip` is Python's package installer.
- PyPI is the package repository.
- Use `requirements.txt` to pin dependencies.
- Always install into a virtual environment (see next topic).
๐ก Note: Use `pip freeze > requirements.txt` to snapshot the exact versions currently installed.