CONTRIBUTING.md

Contributing to Calour

Calour is an open source software package and we welcome community contributions. This document covers what you should do to get started with contributing to Calour

Types of contributions

We're interested in many different types of contributions, including feature additions, bug fixes, continuous integration improvements, and documentation/website updates, additions, and fixes.

When considering contributing to Calour, you should begin by posting an issue to the Calour issue tracker. The information that you include in that post will differ based on the type of contribution. Your contribution will also need to be fully tested where applicable (discussed further below).

• For feature additions, please describe the functionality that you are proposing to add. Before contributing a new feature, it's also a good idea to check whether the functionality exists in other Python packages, or if the feature would fit better in another Python package. For example, low-level statistical methods/tests may fit better in a project that is focused on statistics (e.g., SciPy or statsmodels).

• For bug fixes, please provide a detailed description of the bug so other developers can reproduce it. We take bugs very seriously. Bugs can be related to errors in code, documentation, or tests. Errors in documentation or tests are usually updated in the next scheduled release of Calour. Errors in code that could result in incorrect results or inability to access certain functionality may result in a bug fix release of Calour that is released ahead of schedule.

  You should include the following information in your bug report:

  1. The exact command(s) necessary to reproduce the bug.
  2. A link to all necessary input files for reproducing the bug. These files should only be as large as necessary to create the bug.

• For documentation additions, you should first post an issue describing what you propose to add, where you'd like to add it in the documentation, and a description of why you think it's an important addition.

When you post your issue, the Calour developers will respond to let you know if we agree with the addition or change. It's very important that you go through this step to avoid wasting time working on a feature that we are not interested in including in Calour.

Getting started

"quick fixes"

Some of our issues are labeled as quick fix. Working on these issues is a good way to get started. These are usually small bugs or documentation errors that will only require one or a few lines of code to fix. Getting started by working on one of these issues will allow you to familiarize yourself with our development process before committing to a large amount of work. Please post a comment on the issue if you're interested in working on one of these "quick fixes".

Joining development

Once you are more comfortable with our development process, you can check out the on deck label on our issue tracker. These issues represent what our current focus is in the project. As such, they are probably the best place to start if you are looking to join the conversation and contribute code.

Code review

When you submit code to Calour, it will be reviewed by one or more developers. These reviews are intended to confirm a few points:

• Your code provides relevant changes or additions to Calour (Types of contributions).
• Your code adheres to our coding guidelines (Coding guidelines).
• Your code is sufficiently well-tested (Testing guidelines).
• Your code is sufficiently well-documented (Documentation guidelines).

This process is designed to ensure the quality of Calour and can be a very useful experience for new developers.

Particularly for big changes, if you'd like feedback on your code in the form of a code review as you work, you should request help in the issue that you created and one of the Calour developers will work with you to perform regular code reviews. This can greatly reduce development time (and frustration) so we highly recommend that new developers take advantage of this rather than submitting a pull request with a massive amount of code. That can lead to frustration when the developer thinks they are done but the reviewer requests large amounts of changes, and it also makes it harder to review.

Submitting code to Calour

Calour is hosted on GitHub, and we use GitHub's Pull Request mechanism for reviewing and accepting submissions. You should work through the following steps to submit code.

1. Begin by creating an issue describing your proposed change (see Types of contributions for details).

2. Fork the Calour repository on the GitHub website.

3. Clone your forked repository to the system where you'll be developing with git clone. cd into the calour directory that was created by git clone.

4. Ensure that you have the latest version of all files. This is especially important if you cloned a long time ago, but you'll need to do this before submitting changes regardless. You should do this by adding calour as a remote repository and then pulling from that repository. You'll only need to run the git remote command the first time you do this:

git remote add upstream https://github.com/biocore/calour.git
git checkout master
git pull upstream master

5. Install Calour for development. See Setting up a development environment.

6. Create a new topic branch that you will make your changes in with git checkout -b:

git checkout -b my-topic-branch

What you name your topic branch is up to you, though we recommend including the issue number in the topic branch, since there is usually already an issue associated with the changes being made in the pull request. For example, if you were addressing issue number 42, you might name your topic branch issue-42.

7. Run make test to confirm that the tests pass before you make any changes.

8. Make your changes, add them (with git add), and commit them (with git commit). Don't forget to update associated tests and documentation as necessary. Write descriptive commit messages to accompany each commit. We recommend following NumPy's commit message guidelines, including the usage of commit tags (i.e., starting commit messages with acronyms such ENH, BUG, etc.), although it is not enforced.

9. Please mention your changes in CHANGELOG.md. This file informs Calour users of changes made in each release, so be sure to describe your changes with this audience in mind. It is especially important to note API additions and changes, particularly if they are backward-incompatible, as well as bug fixes. Be sure to make your updates under the section designated for the latest development version of Calour (this will be at the top of the file). Describe your changes in detail under the most appropriate section heading(s). For example, if your pull request fixes a bug, describe the bug fix under the "Bug fixes" section of CHANGELOG.md. Please also include a link to the issue(s) addressed by your changes. See CHANGELOG.md for examples of how we recommend formatting these descriptions.

10. When you're ready to submit your code, ensure that you have the latest version of all files in case some changed while you were working on your edits. You can do this by merging master into your topic branch:

git checkout master
git pull upstream master
git checkout my-topic-branch
git merge master

11. Run make test to ensure that your changes did not cause anything expected to break.

12. Once the tests pass, you should push your changes to your forked repository on GitHub using:

git push origin my-topic-branch

13. Issue a pull request on the GitHub website to request that we merge your branch's changes into calour's master branch. Be sure to include a description of your changes in the pull request, as well as any other information that will help the Calour developers involved in reviewing your code. Please include fixes #<issue-number> in your pull request description or in one of your commit messages so that the corresponding issue will be closed when the pull request is merged (see here for more details). One of the Calour developers will review your code at this stage. If we request changes (which is very common), don't issue a new pull request. You should make changes on your topic branch, and commit and push them to GitHub. Your pull request will update automatically.

Setting up a development environment

Note: Calour must be developed in a Python 3.4 or later environment.

The recommended way to set up a development environment for contributing to Calour is using Anaconda by Continuum Analytics, with its associated command line utility conda. The primary benefit of conda over pip is that on some operating systems (ie Linux), pip installs packages from source. This can take a very long time to install Numpy, scipy, matplotlib, etc. conda installs these packages using pre-built binaries, so the installation is much faster. Another benefit of conda is that it provides both package and environment management, which removes the necessity of using virtualenv separately. Not all packages are available using conda, therefore our strategy is to install as many packages as possible using conda, then install any remaining packages using pip.

1. Install Anaconda

See Continuum's site for instructions. Miniconda provides a fast way to get conda up and running.

2. Create a new conda environment

conda create -n env_name python=3.4 pip

Note that env_name can be any name desired, for example

conda create -n calour python=3.4 pip

3. Activate the environment

This may be slightly different depending on the operating system. Refer to the Continuum site to find instructions for your OS.

source activate env_name

4. Navigate to the calour directory See the section on submitting code.

cd /path/to/calour

5. Install conda requirements

conda install --file ci/conda_requirements.txt

6. Install pip requirements

pip install -r ci/pip_requirements.txt

7. Install Calour

pip install --no-deps -e .

8. Test the installation

make test

Coding guidelines

We adhere to the PEP 8 Python style guidelines and adapt scikit-bio's coding guidelines.

Testing guidelines

In principle, all code that is added to Calour must be unit tested, and the unit test code must be submitted in the same pull request as the library code that you are submitting. We will only merge code that is properly unit tested and that passes the continuous integration build. This build includes, but is not limited to, the following checks:

• Full unit test suite and doctests execute without errors in supported versions of Python 3.
• Documentation can be built.
• Current code coverage is maintained or improved.
• Code passes flake8 checks.

Running make test locally during development will include a subset of the full checks performed by Travis-CI.

The scikit-bio coding guidelines describe our expectations for unit tests. You should review the unit test section before working on your test code.

Documentation guidelines

We strive to keep Calour well-documented, particularly its public-facing API. We use Sphinx to automatically generate human readable documentation from docstrings in the source code. We follow the numpydoc conventions, which helps ensure that the docstrings are easily readable both for human audience and Sphinx. You can also checkout the code of existing modules in Calour to learn how to document your code.

To build and check the documentation, you'll need a development environment set up. And you also need to install Sphinx (and nbsphinx to enable the proper rendering of notebook tutorials). To build the documentation, assuming you are at the top-level Calour directory:

make -C doc clean html

The built HTML documentation will be at doc/build/html/index.html.

Getting help with git

If you're new to git, you'll probably find gitref.org helpful.