---
layout: default
title: Contributing
nav_order: 6
---

# Recommended developer workflow

For developers interested in expanding `pymatgen` for their own purposes, we recommend forking `pymatgen` directly from
the [`pymatgen` GitHub repo](https://github.com/materialsproject/pymatgen). Here's a recommended workflow (updated Jun
2024):

1. Create a free GitHub account (if you don't already have one) and perform the necessary setup (e.g., install SSH keys
   etc.).

1. Fork the `pymatgen` GitHub repo, i.e., go to the
   main [`pymatgen` GitHub repo](https://github.com/materialsproject/pymatgen) and click fork to create a copy of
   the `pymatgen` code base on your own GitHub account.

1. Install `git` on your local machine (if you don't already have it).

1. Clone *your forked repo* to your local machine. You will work mostly with your local repo and only publish changes
   when they are ready to be merged:

    ```sh
    git clone https://github.com/<username>/pymatgen
    cd pymatgen  # Go into pmg directory.
    ```

   Note that the entire Github repo is fairly large because of the presence of test files, but these are necessary for
   rigorous testing.

1. Install the [uv package manager](https://github.com/astral-sh/uv):

    ```sh
    pip install uv
    ```

1. Create a virtual env for pymatgen.

    ```sh
    uv create venv  # A virtual env will be created in the .venv directory in the repo.
    source .venv/bin/activate
    ```

1. Install pymatgen in editable mode with dev and optional dependencies:

    ```sh
    uv pip install -e '.[ci,optional]'
    pre-commit install  # Install pre-commit hook for linters.
    ```

1. Make a new branch for your contributions

    ```sh
    git checkout -b my-new-fix-or-feature  # should be run from up-to-date master
    ```

1. Code (see [Coding Guidelines](#coding-guidelines)). Commit early and commit often. Keep your code up to date. You
   need to add the main repository to the list of your remotes.

    ```sh
    git remote add upstream https://github.com/materialsproject/pymatgen
    ```

   Make sure your repository is clean (no uncommitted changes) and is currently on the master branch. If not, commit or
   stash any changes and switch to the master.

    ```sh
    git checkout master
    ```

   Then you can pull all the new commits from the main line

    ```sh
    git pull upstream master
    ```

   Remember, pull is a combination of the commands fetch and merge, so there may be merge conflicts to be manually
   resolved.

1. Publish your contributions. Assuming that you now have a couple of commits that you would like to contribute to the
   main repository. Please follow the following steps:

    1. If your change is based on a relatively old state of the main repository, then you should probably bring your
       repository up-to-date first to see if the change is not creating any merge conflicts.

    1. Check that everything compiles cleanly and passes all tests. The `pymatgen` repo comes with a complete set of
       tests for all modules. If you have written new modules or methods, you must write tests for the new code as
       well (see [Coding Guidelines](#coding-guidelines)). Install and run `pytest` in your local repo directory and fix
       all errors before continuing further.

    1. If everything is ok, publish the commits to your GitHub repository.

    ```sh
    git push origin master
    ```

1. Now that your commit is published, it doesn't mean that it has already been merged into the main repository. You
   should issue a merge request to `pymatgen` maintainers. They will pull your commits and run their own tests before
   releasing.

"Work-in-progress" pull requests are encouraged, especially if this is your first time contributing to `pymatgen`, and
the maintainers will be happy to help or provide code review as necessary. Put "\[WIP\]" in the title of your pull
request to indicate it's not ready to be merged.

## Coding Guidelines

Given that `pymatgen` is intended to be a long-term code base, we adopt very strict quality control and coding
guidelines for all contributions to `pymatgen`. The following must be satisfied for your contributions to be accepted
into `pymatgen`.

1. **Unit tests** are required for all new modules and methods. The only way to minimize code regression is to ensure
   that all code is well tested. Untested contributions will not be accepted.
1. **Python PEP 8** [code style](https://python.org/dev/peps/pep-0008). We allow a few exceptions when they are
   well-justified (e.g., Element's atomic number is given a variable name of capital Z, in line with accepted scientific
   convention), but generally, PEP 8 must be observed. Code style will be automatically checked for all PRs and must
   pass before any PR is merged. To aid you, you can install and run the same set of formatters and linters that will
   run in CI using

   ```sh
   pre-commit install  # ensures linters are run prior to all future commits
   pre-commit run --files path/to/changed/files  # ensure your current uncommitted changes don't offend linters
   # or
   pre-commit run --all-files  # ensure your entire codebase passes linters
   ```

1. **Python 3**. Check the `pyproject.toml` for the supported Python versions.
1. **Documentation** is required for all modules, classes and methods. In particular, the method doc strings should make
   clear the arguments expected and the return values. For complex algorithms (e.g., an Ewald summation), a summary of
   the algorithm should be provided and preferably with a link to a publication outlining the method in detail.

For the above, if in doubt, please refer to the core classes in `pymatgen` for examples of what is expected.
