Contributing¶

Whether you are a novice or experienced software developer, all contributions and suggestions are welcome!

Getting Started¶

If you are looking to contribute to the pandera codebase, the best place to start is the GitHub “issues” tab. This is also a great place for filing bug reports and making suggestions for ways in which we can improve the code and documentation.

Contributing to the Codebase¶

The code is hosted on GitHub, so you will need to use Git to clone the project and make changes to the codebase.

First create your own fork of pandera, then clone it:

# replace <my-username> with your github username
git clone https://github.com/<my-username>/pandera.git

Once you’ve obtained a copy of the code, create a development environment that’s separate from your existing Python environment so that you can make and test changes without compromising your own work environment.

An excellent guide on setting up python environments can be found here. Pandera offers a environment.yml to set up a conda-based environment and requirements-dev.txt for a virtualenv.

Environment Setup¶

This project recommends using uv to manage the development environment.

pip install uv
uv venv
uv sync --all-extras
source .venv/bin/activate

If you’re on an Apple Silicon machine, you’ll need to install polars via

uv pip install polars-lts-cpu

Run Tests¶

pytest tests/core tests/pandas

Build Documentation Locally¶

make docs

Adding New Dependencies¶

To add new dependencies to the project, first alter the environment.yml file. Then to sync the dependencies from the environment.yml file to the requirements.in, run the following command:

make deps-from-environment.yml

This will invoke python scripts/generate_pip_deps_from_conda.py to convert environment.yml to a requirements.in file. This is so that you can install your development environment using the package manager of your choice like pip, uv, conda, etc.

Moreover to add new extra dependencies in pyproject.toml, it is necessary to add it to the dependencies and [project.optional-dependencies] section.

Set up pre-commit¶

This project uses pre-commit to ensure that code standard checks pass locally before pushing to the remote project repo. Follow the installation instructions, then set up hooks with pre-commit install. After, black, pylint and mypy checks should be run with every commit.

Make sure everything is working correctly by running

pre-commit run --all

Making Changes¶

Before making changes to the codebase or documentation, create a new branch with:

git checkout -b <my-branch>

We recommend following the branch-naming convention described in Making Pull Requests.

DCO-signing Commits¶

This project enforces the DCO standard for contributions, which requires authors to sign off on their commits. This can be done with the -s or --signoff flag:

git commit -s -m 'my commit'

Refer to this guide to add sign-offs retroactivately.

Run the Full Test Suite Locally¶

Before submitting your changes for review, make sure to check that your changes do not break any tests by running:

make nox-tests

This will run the full test suite that matches the tests that are run on github actions, defined in .github/workflows/ci-tests.yml.

Run a Specific Test Suite Locally¶

The above command will run the tests in mamba virtual environments for all of the supported pandera extras packages, versions of python, pandas, etc. To run a test for a specific set of versions, first run:

nox --list

You should see an output like this:

...
* tests-3.9(extra='pandas', pandas='2.1.1', pydantic='1.10.11') -> Run the test suite.
* tests-3.9(extra='strategies', pandas='2.2.3', pydantic='2.10.6') -> Run the test suite.
* tests-3.9(extra='hypotheses', pandas='2.2.3', pydantic='2.10.6') -> Run the test suite.
...

Then run a specific test condition with:

nox -db uv -s "tests(extra='core', pydantic='1.10.11', python='3.9', pandas='2.1.1')"

Project Releases¶

Releases are organized under milestones, which are be associated with a corresponding branch. This project uses semantic versioning, and we recommend prioritizing issues associated with the next release.

Contributing Documentation¶

Maybe the easiest, fastest, and most useful way to contribute to this project (and any other project) is to contribute documentation. If you find an API within the project that doesn’t have an example or description, or could be clearer in its explanation, contribute yours!

You can also find issues for improving documentation under the docs label. If you have ideas for documentation improvements, you can create a new issue here

This project uses Sphinx for auto-documentation and RST syntax for docstrings. Once you have the code downloaded and you find something that is in need of some TLD, take a look at the Sphinx documentation or well-documented examples within the codebase for guidance on contributing.

You can build the html documentation by running nox -s docs. The built documentation can be found in docs/_build.

Contributing Bugfixes¶

Bugs are reported under the bug label, so if you find a bug create a new issue here.

Contributing Enhancements¶

New feature issues can be found under the enhancements label. You can request a feature by creating a new issue here.

Making Pull Requests¶

Once your changes are ready to be submitted, make sure to push your changes to your fork of the GitHub repo before creating a pull request. Depending on the type of issue the pull request is resolving, your pull request should merge onto the appropriate branch:

Bugfixes¶

  • branch naming convention: bugfix/<issue number> or bugfix/<bugfix-name>

  • pull request to: main

Documentation¶

  • branch naming convention: docs/<issue number> or docs/<doc-name>

  • pull request to: release/x.x.x branch if specified in the issue milestone, otherwise main

Enhancements¶

  • branch naming convention: feature/<issue number> or feature/<enhancement-name>

  • pull request to: release/x.x.x branch if specified in the issue milestone, otherwise main

We will review your changes, and might ask you to make additional changes before it is finally ready to merge. However, once it’s ready, we will merge it, and you will have successfully contributed to the codebase!

Questions, Ideas, General Discussion¶

Head on over to the discussion section if you have questions or ideas, want to show off something that you did with pandera, or want to discuss a topic related to the project.

Dataframe Schema Style Guides¶

We have guidelines regarding dataframe and schema styles that are encouraged for each pull request.

If specifying a single column DataFrame, this can be expressed as a one-liner:

DataFrameSchema({"col1": Column(...)})

If specifying one column with multiple lines, or multiple columns:

DataFrameSchema(
    {
        "col1": Column(
            int,
            checks=[
                Check(...),
                Check(...),
            ]
        ),
    }
)

If specifying columns with additional arguments that fit in one line:

DataFrameSchema(
    {"a": Column(int, nullable=True)},
    strict=True
)

If specifying columns with additional arguments that don’t fit in one line:

DataFrameSchema(
    {
        "a": Column(
            int,
            nullable=True,
            coerce=True,
            ...
        ),
        "b": Column(
            ...,
        )
    },
    strict=True)

Deprecation policy¶

This project adopts a rolling policy regarding the minimum supported version of its dependencies, based on NEP 29:

  • Python: 42 months

  • NumPy: 24 months

  • Pandas: 18 months

This means the latest minor (X.Y) version from N months prior. Patch versions (x.y.Z) are not pinned, and only the latest available at the moment of publishing the release is guaranteed to work.