Working with Python Projects

Overview

Questions

• What is a Python project?
• How do I create a Python project and run it?

Objectives

• Create a Python project with uv.
• Add dependencies to a Python project and run code.
• Collaborate on a Python project with other developers.

What is a Python project?

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A Python project is a directory containing multiple Python files. The metadata for the Python project is contained in a pyproject.toml file which contains information about the Python version required for the project as well as dependencies required by the project.

Create a Python Project with uv

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Use the init command in uv to create a directory for a Python project. The command shown below creates a directory called my-project that represents a Python project.

BASH

$ uv init my-project

The contents of the directory are shown below. Notice that uv automatically sets up the directory as a Git repository (.git/) and includes an ignore file (.gitignore) to prevent unnecessary files from being committed to version control. The .python-version file contains the project’s default Python version.

BASH

$ cd my-project

OUTPUT

my-project/
├── .git/
├── .gitignore
├── .python-version
├── main.py
├── pyproject.toml
└── README.md

You can also use uv to add dependencies to the project. Here we add the NumPy package to the project which will automatically create a virtual environment (.venv/) and install the NumPy package into the virtual environment. A uv.lock file is also created to ensure that developers working on the project are using a consistent set of package versions.

BASH

$ uv add numpy

OUTPUT

my-project/
├── .git/
├── .gitignore
├── .python-version
├── .venv/
├── main.py
├── pyproject.toml
├── README.md
└── uv.lock

Notice that uv automatically added the NumPy package as a dependency of the project to the pyproject.toml file:

TOML

# pyproject.toml

[project]
name = "my-project"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.13"
dependencies = [
    "numpy>=2.3.0",
]

Lastly, to run a script such as main.py in the project, just use the uv run command as shown below:

PYTHON

# main.py

import numpy as np


def main():
    print("Hello from my-project!")

    a = np.array([1, 2, 3, 4, 5])
    print("a is", a)


if __name__ == "__main__":
    main()

BASH

$ uv run main.py

OUTPUT

Hello from my-project!
a is [1 2 3 4 5]

Collaborate on Python Projects with uv

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Collaborating on a Python project can be a daunting task because everyone needs to use the same version of Python and have the same dependencies (and versions of dependencies) installed in their virtual environment. For projects that contain a pyproject.toml file, uv makes collaboration very simple because it handles all of the installation steps for you. The basic steps for collaborating on a Python project with uv are:

1. Download and install uv
2. Download the Python project
3. Run the Python code in the project with the uv run command

That’s it! There is no need to install Python on your computer, or create and activate a virtual environment, or install dependencies for running code in the Python project. This is all handled by uv when you run the code.

For projects that don’t provide a pyproject.toml file, you may need to manually create the virtual environment with uv then install dependencies with pip as summarized below. Unfortunately, there are many ways to setup a Python project, so the steps needed to install and run such a project may vary if there is no pyproject.toml file.

1. Download and install uv
2. Download the Python project
3. Create the virtual environment for a specific Python version with uv venv --python 3.12
4. Install dependencies in the environment with the uv pip install command
5. Activate the virtual environment and run code with the python command

Key Points

• A Python project is just a directory of Python files with a pyproject.toml file for configuration.
• Use uv to easily add dependencies to a Python project and collaborate with other developers.