Development workflow#

Contributing to mne-denoise#

Thank you for your interest in contributing to mne-denoise! This guide will help you get started with contributing code, documentation, or bug reports.

Table of Contents#

Code of Conduct#

This project follows the MNE-Python Code of Conduct. By participating, you are expected to uphold this code.

Getting Started#

Prerequisites#

  • Python 3.10 or higher

  • Git

  • A GitHub account

Fork and Clone#

  1. Fork the repository on GitHub by clicking the “Fork” button.

  2. Clone your fork locally:

    git clone https://github.com/<your-username>/mne-denoise.git
cd mne-denoise

  3. Add the upstream remote:

    git remote add upstream https://github.com/mne-tools/mne-denoise.git

Development Environment#

We recommend using a virtual environment for development.

Using conda#

# Create environment
conda create -n mne-denoise python=3.12
conda activate mne-denoise

# Install in editable mode
pip install -e ".[dev,docs]"
pre-commit install

Workflow#

1. Create a Branch#

Always create a new branch for your work:

# Sync with upstream first
git fetch upstream
git checkout main
git merge upstream/main

# Create feature branch
git checkout -b feature/my-new-feature
# or for bug fixes:
git checkout -b fix/issue-123

2. Make Your Changes#

  • Write clean, readable code

  • Follow the code style guidelines (see below)

  • Add tests for new functionality

  • Update documentation as needed

3. Commit Your Changes#

Write clear, descriptive commit messages:

git add .
git commit -m "Add support for custom frequency bands in BandpassBias"

Commit message guidelines:

  • Use present tense (“Add feature” not “Added feature”)

  • Use imperative mood (“Move cursor to…” not “Moves cursor to…”)

  • Keep the first line under 72 characters

  • Reference issues when relevant (“Fix #123: …”)

4. Keep Your Branch Updated#

git fetch upstream
git rebase upstream/main

5. Add Changelog Entry#

We use towncrier to manage our changelog. This prevents merge conflicts and ensures standardized release notes.

When you create a Pull Request, please add a changelog entry file in docs/changes/devel/. The file name should be the change type (e.g., feature.rst, bugfix.rst).

For detailed instructions and available types, see docs/changes/README.md.

Author Attribution: We encourage contributors to include their name in the changelog entry if they wish to be highlighted. In Markdown, you can link to your GitHub profile (e.g., ... (by [@YourUser](...))).

Code Style#

We use Ruff for linting and formatting, configured to follow PEP 8 with NumPy docstring conventions.

Automatic Formatting#

Pre-commit hooks will automatically format your code on commit. To run manually:

# Check for linting errors
ruff check .

# Auto-fix linting errors
ruff check . --fix

# Format code
ruff format .

# Run all pre-commit hooks
pre-commit run --all-files

Docstring Style#

We use NumPy-style docstrings. Example:

def compute_dss(data, bias, n_components=None):
    """Compute DSS spatial filters.

    Parameters
    ----------
    data : ndarray, shape (n_channels, n_times)
        Input data matrix.
    bias : LinearDenoiser
        Bias function that emphasizes signal of interest.
    n_components : int, optional
        Number of components to return. If None, returns all.

    Returns
    -------
    filters : ndarray, shape (n_channels, n_components)
        Spatial filters sorted by eigenvalue.
    eigenvalues : ndarray, shape (n_components,)
        Corresponding eigenvalues.

    Examples
    --------
    >>> from mne_denoise.dss import compute_dss, AverageBias
    >>> filters, eigenvalues = compute_dss(data, AverageBias())

    See Also
    --------
    DSS : Scikit-learn compatible transformer.

    References
    ----------
    .. [1] de Cheveigné, A., & Simon, J. Z. (2008). Denoising based on
           spatial filtering. Journal of Neuroscience Methods.
    """

Testing#

We use pytest for testing. All new code should have tests.

Running Tests#

# Run all tests
pytest

# Run with coverage
pytest --cov=mne_denoise --cov-report=html

# Run specific test file
pytest tests/test_linear_dss.py

# Run specific test
pytest tests/test_linear_dss.py::test_dss_epochs -v

# Run tests matching a pattern
pytest -k "zapline" -v

Writing Tests#

  • Place tests in the tests/ directory

  • Name test files test_*.py

  • Name test functions test_*

  • Use descriptive test names that explain what is being tested

  • Use fixtures for common setup

  • Plotting tests use the non-interactive Matplotlib backend configured in tests/conftest.py, and figures are closed automatically after each test

  • Pass show=False when testing plotting functions

  • For optional dependencies, prefer pytest.importorskip(...)

Example test:

import numpy as np
import pytest
from mne_denoise.dss import DSS, AverageBias


@pytest.fixture
def sample_epochs():
    """Create sample epochs for testing."""
    rng = np.random.default_rng(42)
    return rng.standard_normal((10, 32, 1000))


def test_dss_fit_transform_returns_correct_shape(sample_epochs):
    """Test that DSS returns sources with expected shape."""
    dss = DSS(bias=AverageBias(), n_components=5)
    sources = dss.fit_transform(sample_epochs)

    assert sources.shape[0] == 5  # n_components
    assert sources.shape[1] == sample_epochs.shape[2]  # n_times

Coverage Requirements#

  • Aim for 100% coverage on new code

  • The CI will report coverage; check the Codecov report on your PR

  • View local coverage report: open htmlcov/index.html

Documentation#

Documentation is built with Sphinx and hosted on GitHub Pages.

Building Docs Locally#

# Build HTML documentation
make -C docs html

# View in browser
open docs/_build/html/index.html  # macOS
xdg-open docs/_build/html/index.html  # Linux
start docs/_build/html/index.html  # Windows

Documentation Structure#

  • docs/api.rst - API reference (auto-generated from docstrings)

  • docs/getting-started.rst - Installation and quick start

  • docs/dss.md - DSS module guide

  • examples/ - Gallery examples (rendered by sphinx-gallery)

Adding Examples#

Examples are Python scripts in the examples/ directory:

  1. Create a file with prefix plot_ (e.g., plot_my_example.py)

  2. Follow the sphinx-gallery format with docstring headers

  3. Examples are automatically built and included in the gallery

Example template:

"""
Title of Example
================

Brief description of what this example demonstrates.
"""

# %%
# Section Header
# --------------
# Explanation text...

import mne_denoise

# Your code here...

Submitting Changes#

Pull Request Process#

  1. Push your branch to your fork:

    git push origin feature/my-new-feature

  2. Open a Pull Request on GitHub against the main branch.

  3. Fill out the PR template with:

    • Description of changes

    • Related issue(s)

    • Type of change

    • Checklist items

  4. Wait for CI to complete. All checks must pass.

  5. Address review feedback by pushing additional commits.

  6. Squash and merge once approved (maintainers will do this).

PR Checklist#

Before submitting, ensure:

  • [ ] Code follows the project style (ruff check . passes)

  • [ ] Code is formatted (ruff format . produces no changes)

  • [ ] All tests pass (pytest exits cleanly)

  • [ ] New code has tests with good coverage

  • [ ] Documentation is updated if needed

  • [ ] Documentation builds cleanly (make -C docs html)

  • [ ] CHANGELOG.md is updated for user-facing changes

  • [ ] Commit messages are clear and descriptive

Issue Guidelines#

Reporting Bugs#

When reporting a bug, please include:

  1. Description: What happened vs. what you expected

  2. Reproduction steps: Minimal code to reproduce the issue

  3. Environment: Python version, OS, package versions

  4. Error message: Full traceback if applicable

Use the bug report template when creating an issue.

Requesting Features#

For feature requests:

  1. Check if it already exists or is planned

  2. Describe the use case and motivation

  3. Provide examples of how it would be used

  4. Consider if you’d like to implement it yourself

Questions?#

Thank you for contributing!