Contributing to tedana

This document explains contributing to tedana at a very high level, with a focus on project governance and development philosophy. For a more practical guide to the tedana development, please see our contributing guide.

Governance

Governance is a hugely important part of any project. It is especially important to have clear process and communication channels for open source projects that rely on a distributed network of volunteers, such as tedana.

tedana is currently supported by a small group of five core developers. Even with only five members involved in decision making processes, we’ve found that setting expectations and communicating a shared vision has great value.

By starting the governance structure early in our development, we hope to welcome more people into the contributing team. We are committed to continuing to update the governance structures as necessary. Every member of the tedana community is encouraged to comment on these processes and suggest improvements.

As the first interim Benevolent Dictator for Life (BDFL), Elizabeth DuPre is ultimately responsible for any major decisions pertaining to tedana development. However, all potential changes are explicitly and openly discussed in the described channels of communication, and we strive for consensus amongst all community members.

Code of conduct

All tedana community members are expected to follow our code of conduct during any interaction with the project. That includes—but is not limited to—online conversations, in-person workshops or development sprints, and when giving talks about the software.

As stated in the code, severe or repeated violations by community members may result in exclusion from collective decision-making and rejection of future contributions to the tedana project.

tedana’s development philosophy

In contributing to any open source project, we have found that it is hugely valuable to understand the core maintainers’ development philosophy. In order to aid other contributors in on-boarding to tedana development, we have therefore laid out our shared opinion on several major decision points. These are:

1. Which options are available to users?,
2. Structuring project developments,
3. Is tedana backwards compatible with MEICA?,
4. How does tedana future-proof its development?, and
5. When to release a new version

Which options are available to users?

The tedana developers are committed to providing useful and interpretable outputs for a majority of use cases.

In doing so, we have made a decision to embrace defaults which support the broadest base of users. For example, the choice of an independent component analysis (ICA) cost function is part of the tedana pipeline that can have a significant impact on the results and is difficult for individual researchers to form an opinion on.

The tedana “opinionated approach” is therefore to provide reasonable defaults and to hide some options from the top level workflows.

This decision has two key benefits:

1. By default, users should get high quality results from running the pipelines, and
2. The work required of the tedana developers to maintain the project is more focused and somewhat restricted.

It is important to note that tedana is shipped under an LGPL2 license which means that the code can—at all times—be cloned and re-used by anyone for any purpose.

“Power users” will always be able to access and extend all of the options available. We encourage those users to feed back their work into tedana development, particularly if they have good evidence for updating the default values.

We understand that it is possible to build the software to provide more options within the existing framework, but we have chosen to focus on the 80 percent use cases.

You can provide feedback on this philosophy through any of the channels listed on the tedana support page.

Structuring project developments

The tedana developers have chosen to structure ongoing development around specific goals. When implemented successfully, this focuses the direction of the project and helps new contributors prioritize what work needs to be completed.

We have outlined our goals for tedana in our The tedana roadmap, which we encourage all contributors to read and give feedback on. Feedback can be provided through any of the channels listed on our support page.

In order to more directly map between our The tedana roadmap and ongoing project issues, we have also created milestones in our github repository.

This allows us to:

1. Label individual issues as supporting specific aims, and
2. Measure progress towards each aim’s concrete deliverable(s).

Is tedana backwards compatible with MEICA?

The short answer is No.

There are two main reasons why. The first is that mdp, the python library used to run the ICA decomposition core to the original MEICA method, is no longer supported.

In November 2018, the tedana developers made the decision to switch to scikit-learn to perform these analyses. scikit-learn is well supported and under long term development. tedana will be more stable and have better performance going forwards as a result of this switch, but it also means that exactly reproducing previous MEICA analyses is not possible.

The other reason is that the core developers have chosen to look forwards rather than maintaining an older code base. As described in the Governance section, tedana is maintained by a small team of volunteers with limited development time. If you’d like to use MEICA as has been previously published the code is available on bitbucket and freely available under a LGPL2 license.

How does tedana future-proof its development?

tedana is a reasonably young project that is run by volunteers. No one involved in the development is paid for their time. In order to focus our limited time, we have made the decision to not let future possibilities limit or over-complicate the most immediately required features. That is, to not let the perfect be the enemy of the good.

While this stance will almost certainly yield ongoing refactoring as the scope of the software expands, the team’s commitment to transparency, reproducibility, and extensive testing mean that this work should be relatively manageable.

We hope that the lessons we learn building something useful in the short term will be applicable in the future as other needs arise.

When to release a new version

In the broadest sense, we have adopted a “you know it when you see it” approach to releasing new versions of the software.

To try to be more concrete, if a change to the project substantially changes the user’s experience of working with tedana, we recommend releasing an updated version. Additional functionality and bug fixes are very clear opportunities to release updated versions, but there will be many other reasons to update the software as hosted on PyPi.

To give two concrete examples of slightly less obvious cases:

1. A substantial update to the documentation that makes tedana easier to use would count as a substantial change to tedana and a new release should be considered.

2. In contrast, updating code coverage with additional unit tests does not affect the user’s experience with tedana and therefore does not require a new release.

Any member of the tedana community can propose that a new version is released. They should do so by opening an issue recommending a new release and giving a 1-2 sentence explanation of why the changes are sufficient to update the version. More information about what is required for a release to proceed is available in the Release Checklist.

Release Checklist

This is the checklist of items that must be completed when cutting a new release of tedana. These steps can only be completed by a project maintainer, but they are a good resource for releasing your own Python projects!

1. All continuous integration must be passing and docs must be building successfully.
2. Create a new release, using the GitHub guide for creating a release on GitHub. Release-drafter should have already drafted release notes listing all changes since the last release; check to make sure these are correct.
3. Pulling from the master branch, locally build a new copy of tedana and upload it to PyPi.

We have set up tedana so that releases automatically mint a new DOI with Zenodo; a guide for doing this integration is available here.