Contributing to lenstronomy

Contributor Guidelines

We welcome EVERY contribution from EVERYONE! Please read and adhere to our code of conduct.

GitHub Workflow

Fork and Clone the lenstronomy Repository

You should only need to do this step once

First fork the lenstronomy repository. A fork is your own remote copy of the repository on GitHub. To create a fork:

  1. Go to the lenstronomy GitHub Repository

  2. Click the Fork button (in the top-right-hand corner)

  3. Choose where to create the fork, typically your personal GitHub account

Next clone your fork. Cloning creates a local copy of the repository on your computer to work with. To clone your fork:

git clone https://github.com/<your-account>/lenstronomy.git

Finally, add the lenstronomyproject repository as a remote. This will allow you to fetch changes made to the codebase. To add the lenstronomyproject remote:

cd lenstronomy
git remote add lenstronomyproject https://github.com/lenstronomy/lenstronomy.git

Install your local lenstronomy version

To enable that your new code gets accessible by Python also outside of the development environment, make sure all previous versions of lenstronomy are uninstalled, and then install your version of lenstronomy (aka add the software to the Python path)

cd lenstronomy
python setup.py develop --user

Alternatively, create virtual environments for the development (recommended for advanced usage with multiple branches).

Create a branch for your new feature

Create a branch off the lenstronomyproject main branch. Working on unique branches for each new feature simplifies the development, review, and merge processes by maintaining logical separation. To create a feature branch:

git fetch lenstronomyproject
git checkout -b <your-branch-name> lenstronomyproject/main

Hack away!

Write the new code you would like to contribute and commit it to the feature branch on your local repository. Ideally, commit small units of work often with clear and descriptive commit messages describing the changes you made. To commit changes to a file:

git add file_containing_your_contribution
git commit -m 'Your clear and descriptive commit message'

Push the contributions in your feature branch to your remote fork on GitHub:

git push origin <your-branch-name>

Note: The first time you push a feature branch, you will probably need to use –set-upstream origin to link to your remote fork:

git push --set-upstream origin <your-branch-name>

Open a Pull Request

When you feel that work on your new feature is complete, you should create a Pull Request. This will propose your work to be merged into the main lenstronomy repository.

  1. Go to lenstronomy Pull Requests

  2. Click the green New pull request button

  3. Click compare across forks

  4. Confirm that the base fork is lenstronomy/lenstronomy and the base branch is main

  5. Confirm the head fork is <your-account>/lenstronomy and the compare branch is <your-branch-name>

  6. Give your pull request a title and fill out the template for the description

  7. Click the green Create pull request button

Updating your branch

As you work on your feature, new commits might be made to the lenstronomy/lenstronomy main branch. You will need to update your branch with these new commits before your pull request can be accepted. You can achieve this in a few different ways:

  • If your pull request has no conflicts, click Update branch

  • If your pull request has conflicts, click Resolve conflicts, manually resolve the conflicts and click Mark as resolved

  • merge the lenstronomyproject main branch from the command line:

    git fetch lenstronomyproject
git merge lenstronomyproject/main

  • rebase your feature branch onto the lenstronomy main branch from the command line:

    git fetch lenstronomyproject
git rebase lenstronomyproject/main

Warning: It is bad practice to rebase commits that have already been pushed to a remote such as your fork. Rebasing creates new copies of your commits that can cause the local and remote branches to diverge. git push --force will overwrite the remote branch with your newly rebased local branch. This is strongly discouraged, particularly when working on a shared branch where you could erase a collaborator’s commits.

For more information about resolving conflicts, see the GitHub guides:

More Information

More information regarding the usage of GitHub can be found in the GitHub Guides.

Coding Guidelines

Before your pull request can be merged into the codebase, it will be reviewed by one of the lenstronomy developers and required to pass a number of automated checks. Below are a minimum set of guidelines for developers to follow:

General Guidelines

  • lenstronomy is compatible with Python>=3.7 (see setup.cfg). lenstronomy does not support backwards compatibility with Python 2.x; six, __future__ and 2to3 should not be used.

  • All contributions should follow the PEP8 Style Guide for Python Code. We recommend using flake8 to check your code for PEP8 compliance. One exception to the PEP8 guidelines is that the maximum allowed line length is 88 characters (following `black` style).

  • Importing lenstronomy should only depend on having NumPy, SciPy and Astropy installed.

  • Code is grouped into submodules based e.g. LensModel, LightModel or ImSim. There is also a Util submodule for general utility functions.

  • For more information, see the Astropy Coding Guidelines.

Unit Tests

Pull requests will require existing unit tests to pass before they can be merged. Additionally, new unit tests should be written for all new public methods and functions. Unit tests for each submodule are contained in subdirectories called tests and you can run them locally using python setup.py test. For more information, see the Astropy Testing Guidelines.

Docstrings

All public classes, methods, and functions require docstrings. The docstring format should follow the reStructuredText format. You can build the documentation locally by installing sphinx and calling python setup.py build_docs. Docstrings should include the following sections:

  • Description

  • Parameters

  • Notes

  • Examples

  • References

For more information, see the Astropy guide to Writing Documentation.

This page is inspired by the Contributions guidelines of the Skypy project.