Setting up Matplotlib for development#

To set up Matplotlib for development follow these steps:

Retrieve the latest version of the code#

Matplotlib is hosted at https://github.com/matplotlib/matplotlib.git.

You can retrieve the latest sources with the command (see Set up your fork for more details)

git clone https://github.com/matplotlib/matplotlib.git

git clone [email protected]:matplotlib/matplotlib.git

This requires you to setup an SSH key in advance, but saves you from typing your password at every connection.

This will place the sources in a directory matplotlib below your current working directory. Change into this directory:

cd matplotlib

Create a dedicated environment#

You should set up a dedicated environment to decouple your Matplotlib development from other Python and Matplotlib installations on your system.

The simplest way to do this is to use either Python's virtual environment venv or conda.

Create a new venv environment with

python -m venv <file folder location>

and activate it with one of the following

source <file folder location>/bin/activate  # Linux/macOS
<file folder location>\Scripts\activate.bat  # Windows cmd.exe
<file folder location>\Scripts\Activate.ps1  # Windows PowerShell

Create a new conda environment with

conda env create -f environment.yml

You can use mamba instead of conda in the above command if you have mamba installed.

Activate the environment using

conda activate mpl-dev

Remember to activate the environment whenever you start working on Matplotlib.

Install Matplotlib in editable mode#

Install Matplotlib in editable mode from the matplotlib directory using the command

python -m pip install -ve .

The 'editable/develop mode', builds everything and places links in your Python environment so that Python will be able to import Matplotlib from your development source directory. This allows you to import your modified version of Matplotlib without re-installing after every change. Note that this is only true for *.py files. If you change the C-extension source (which might also happen if you change branches) you will have to re-run python -m pip install -ve .

Install additional development dependencies#

See Dependencies for building Matplotlib.

Install pre-commit hooks (optional)#

pre-commit hooks automatically check flake8 and other style issues when you run git commit. The hooks are defined in the top level .pre-commit-config.yaml file. To install the hooks

python -m pip install pre-commit
pre-commit install

The hooks can also be run manually. All the hooks can be run, in order as listed in .pre-commit-config.yaml, against the full codebase with

pre-commit run --all-files

To run a particular hook manually, run pre-commit run with the hook id

pre-commit run <hook id> --all-files