The future of Fatiando a Terra

I started developing the Fatiando a Terra Python library in 2010. Since then, many other open-source Python libraries for geophysics have appeared, each with unique capabilities. In this post, I'll explore where I think Fatiando fits in this larger ecosystem and how we can better fill our niche.

What is Fatiando a Terra?

Fatiando is a Python library for modeling and inversion in geophysics. It's composed of different subpackages:

Fatiando's niche

We set out with the goal of modeling the whole Earth using all geophysical methods. Humble, right? Turns out this is extremely hard and way beyond what a couple of grad students can do in a couple of years. Back then, there were very few Python geophysical modeling libraries. A decade later, the ecosystem has expanded. The five currently on going projects of which I'm aware are (let me know in the comments if I missed any):

The two projects that are most similar to us (SimPEG and pyGIMLi) implement flexible partial differential equation solvers that they use to run all forward modeling calculations. This makes a lot of sense because it gives them a unified framework to model most geophysical methods. It is the most sensible approach to build joint inversions of multiple geophysical datasets. However, there are some inverse problems that don't fit this paradigm, like inverting Moho relief from gravity data and some non-conventional inversion algorithms (see the animation below).

It's no coincidence that Fatiando mostly contains the tools needed to implement this type of inverse problem (i.e., analytical solutions for the gravity and magnetic fields of geometric objects). This is precisely the type of research that we do at the PINGA lab. We also develop processing methods for gravity and magnetics.

The niche I see for Fatiando is in gravity and magnetic methods, particularly using these analytical solutions. The processing functions are an important feature because there are hardly any open-source alternatives out there to commercial software like Oasis Montaj and Intrepid.

The current state

Fatiando has grown over the years as I slowly learned how to develop and maintain an open-source Python project. As a result, the codebase is littered with the bad choices that I made along the way. The most urgent problems that need to be fixed are:

A way forward

The best way forward for Fatiando that I can see, is to become an ecosystem of specialized tools and libraries, rather than a single Python package. Having things in separate libraries allows us to better indicate what is robust and professional and what is experimental or meant as a teaching tool. In particular, the meshing library has some overlap with discretize and we should be considering a merger of our projects. Separating what we have in a library will help us articulate the requirements of Fatiando so that we can see if a merger is beneficial. We can also include experimental libraries (like fatiando.seismic.wavefd) and CLI or GUI programs as independent projects.

This is how I envision the Fatiando ecosystem in the future (I have already started working on some of these projects):

All of these packages will be tied together in the fatiando Github organization and the fatiando.org website, which will include instructions for installing the entire stack. The website will also link to individual packages (as is done right now for the subpackages) and any other project in the fatiando umbrella. Members of the organization will be free to create new repositories and we'll provide a template for doing so.

The requirements and goals for these new packages are:

This is how I think we could implement this:

  1. Release Fatiando 0.6 with what we currently have in the master branch along with a note that this will be the last release to support Python 2.7.
  2. Create a package template repository with the shared infrastructure (setup.py, docs, continuous integration configuration, Makefile, testing, etc).
  3. Start repositories for each of the packages listed above.
  4. Specify clear goals for each package and an example of how we want the API to look.
  5. Focus on redesigning the inversion package first. This is the basis for many other packages.
  6. Slowly copy over code from fatiando/fatiando while ensuring that everything is tested and documented.

Help!

The goal of all these changes is to make Fatiando better for users and developers by making the code more robust and well documented. I'm curious to know what the Python geophysics community thinks about all of this. Do I have it all wrong? What should be done differently? And most importantly, would you like to help?


Comments? Leave one below or let me know on Twitter @leouieda.
Found a typo/mistake? Send a fix through Github and I'll happily merge it (plus you'll feel great because you helped someone). All you need is an account and 5 minutes!

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