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

Option 1: miniconda Setup

Install miniconda, then run:

conda create -n pandera-dev python=3.8  # or any python version 3.7+
conda env update -n pandera-dev -f environment.yml
conda activate pandera-dev
pip install -e .

Option 2: virtualenv Setup

pip install virtualenv
virtualenv .venv/pandera-dev
source .venv/pandera-dev/bin/activate
pip install -r requirements-dev.txt
pip install -e .

Run Tests

pytest tests

Build Documentation Locally

make docs

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.

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:

# option 1: if you're working with conda (recommended)
$ make nox-conda

# option 2: if you're working with virtualenv
$ make nox

Option 2 assumes that you have python environments for all of the versions that pandera supports.

Using mamba (optional)

You can also use mamba, which is a faster implementation of miniconda, to run the nox test suite. Simply install it via conda-forge, and make nox-conda should use it under the hood.

$ conda install -c conda-forge mamba
$ make nox-conda

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: dev

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 dev

Enhancements

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

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

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)