testbed/matplotlib__matplotlib/doc/devel/development_setup.rst

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.. _installing_for_devs:

=====================================
Setting up Matplotlib for development
=====================================

To set up Matplotlib for development follow these steps:

.. contents::
   :local:

Fork the Matplotlib repository
==============================

Matplotlib is hosted at https://github.com/matplotlib/matplotlib.git. If you
plan on solving issues or submit pull requests to the main Matplotlib
repository, you should first *fork* this repository by visiting
https://github.com/matplotlib/matplotlib.git and clicking on the
``Fork`` button on the top right of the page (see
`the GitHub documentation <https://docs.github.com/get-started/quickstart/fork-a-repo>`__ for more details.)

Retrieve the latest version of the code
=======================================

Now that your fork of the repository lives under your GitHub username, you can
retrieve the most recent version of the source code with one of the following
commands (replace ``<your-username>`` with your GitHub username):

.. tab-set::

   .. tab-item:: https

      .. code-block:: bash

         git clone https://github.com/<your-username>/matplotlib.git

   .. tab-item:: ssh

      .. code-block:: bash

         git clone git@github.com:<your-username>/matplotlib.git

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

      .. _SSH key: https://docs.github.com/en/authentication/connecting-to-github-with-ssh


This will place the sources in a directory :file:`matplotlib` below your
current working directory and set the remote name ``origin`` to point to your
fork. Change into this directory before continuing::

    cd matplotlib

Now set the remote name ``upstream`` to point to the Matplotlib main repository:

.. tab-set::

   .. tab-item:: https

      .. code-block:: bash

         git remote add upstream https://github.com/matplotlib/matplotlib.git

   .. tab-item:: ssh

      .. code-block:: bash

         git remote add upstream git@github.com:matplotlib/matplotlib.git

You can now use ``upstream`` to retrieve the most current snapshot of the source
code, as described in :ref:`development-workflow`.

.. dropdown:: Additional ``git`` and ``GitHub`` resources
   :color: info
   :open:

   For more information on ``git`` and ``GitHub``, see:

   * `Git documentation <https://git-scm.com/doc>`_
   * `GitHub-Contributing to a Project
     <https://git-scm.com/book/en/v2/GitHub-Contributing-to-a-Project>`_
   * `GitHub Skills <https://skills.github.com/>`_
   * :ref:`using-git`
   * :ref:`git-resources`
   * `Installing git <https://git-scm.com/book/en/v2/Getting-Started-Installing-Git>`_
   * `Managing remote repositories
     <https://docs.github.com/en/get-started/getting-started-with-git/managing-remote-repositories>`_
   * https://tacaswell.github.io/think-like-git.html
   * https://tom.preston-werner.com/2009/05/19/the-git-parable.html

.. _dev-environment:

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`_.

.. _venv: https://docs.python.org/3/library/venv.html
.. _conda: https://docs.conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html

.. tab-set::

   .. tab-item:: venv environment

      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

      On some systems, you may need to type ``python3`` instead of ``python``.
      For a discussion of the technical reasons, see `PEP-394 <https://peps.python.org/pep-0394>`_.

   .. tab-item:: conda environment

      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.

      .. _mamba: https://mamba.readthedocs.io/en/latest/

      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 :file:`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 pre-commit hooks
========================
`pre-commit <https://pre-commit.com/>`_ hooks save time in the review process by
identifying issues with the code before a pull request is formally opened. Most
hooks can also aide in fixing the errors, and the checks should have
corresponding :ref:`development workflow <development-workflow>` and
:ref:`pull request <pr-guidelines>` guidelines. Hooks are configured in
`.pre-commit-config.yaml <https://github.com/matplotlib/matplotlib/blob/main/.pre-commit-config.yaml?>`_
and include checks for spelling and formatting, flake 8 conformity, accidentally
committed files, import order, and incorrect branching.

Install pre-commit hooks ::

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

Hooks are run automatically after the ``git commit`` stage of the
:ref:`editing workflow<edit-flow>`. When a hook has found and fixed an error in a
file, that file must be *staged and committed* again.

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