Martin Yeo

Software Developer at the Met Office

In 2019 I joined the UK Met Office, developing and supporting software for analysing weather and climate data. Our team helped scientists of all kinds use the open source Python ecosystem to enhance the forecast and perform research. We did this in three ways:

Learning something completely new

Unlike all previous roles, I had no existing grounding in the tools used. Python was entirely new for me, and even object-oriented programming was fairly unfamiliar (VBA being merely an enhancement to existing Excel functionality). Git and GitHub were also markedly different from my previous source control experience (in a good way!). Getting up to speed as quickly as possible meant swallowing pride and being willing to ask questions, no matter how basic, no matter how big the group. I looked for any opportunities to frame my learning in the forms that work best for me - primarily via solving practical problems.

Fresh input to the team

The team was welcoming and open to my input even as a newcomer, so I made sure to be as forthcoming as possible while my perspective was fresh - this window is always a short one. This approach proved particularly valuable in the sphere of user support; from my previous role I was able to share many patterns and anti-patterns about fostering trust in one’s user-base.

Engaging the user community

I quickly became the team’s main advocate for user engagement. User support was often seen as a chore, to be cleared as quickly as possible before returning to development work (a cliché in software development). I pushed for a more strategic attitude; time with users is an opportunity to:

I demonstrated how I saw this as a virtuous cycle where the outcomes of more support help us deliver increased value for less work, encouraging more users, some of whom will need support. This was especially important when producing something where users and developers each provided a share of the total expertise - we only had the full set by working together!

My championing in this area resulted in more resource being given to support and the team being seen as more approachable, and this did indeed uncover new opportunities for improvement.

Making routine tasks easier

The team had a number of routine administrative tasks to achieve various things including: organising walk-in ‘surgeries’, tracking who we had given support, and sharing tips/tricks as we discovered them. These were complex enough to be a significant interruption to team members’ workflows, while their nature prevented full automation. I focussed on the next best option: making them as simple as possible. I invested time in learning how we could get the best from Microsoft 365, including SharePoint lists, Forms and Power Automate. I also created checklists wherever we had a series of rote steps. The result allowed the team to deliver the same value but with much less complexity / context-switching.

Creative development

9 months after starting, the team took on a project to adapt our main software library - Iris - to handle data located on an unstructured mesh. This broke the mould compared to ‘typical’ software projects:

This was therefore an unusually creative form of software development, with lots of conceptual discussions as well as programming tasks. It was particularly challenging to design a Minimum Viable Product that would be able to evolve as users learned this space, since we didn’t know how things would evolve.

We took inspiration from popular scientific Python packages such as NumPy: were possible we avoided adding functions for specific purposes and instead built flexible base architecture that people could use to solve a variety of problems. This included providing many examples in the documentation to give users confidence.

As some of the first people to consider these problems, it often fell to us to explain the core concepts of unstructured meshes to our user base. This ranged from being present in office discussions, to giving presentations, to writing documentation.

We delivered our MVP in 2022, and immediately saw user engagement with what we were offering. Giving early adopters something to work with allowed much more constructive planning of next steps, thanks to the quality of feedback.

Performance benchmarking

Unstructured meshes require much larger files for a given data resolution, so benchmarking and profiling performance became a key concern. I was tasked with introducing performance into our ‘test harness’, which turned out to be highly nuanced and technical task.

We found a few existing packages designed to simplify the issue, although they each came with their own opinionated answers to the above questions. Once we chose Airspeed Velocity, a significant challenge was devising customisation suitable to what we needed to achieve.

By being the designated team member for benchmarking, I was able to keep the various difficulties in mind and to make sure everyone else in the team understood the problems and our solutions. Having performance as part of Iris (see here) has improved our understanding of the transition to unstructured meshes, as well as catching various changes in performance we would otherwise have missed.

Part of an international community

Working in open source introduced me an exciting community. Often multiple teams around the world will be trying different solutions to the same problem; users are free to pick the best tool from those available, and development teams can collaborate to provide solutions that they couldn’t individually. The best packages in this ecosystem are as interoperable with other packages as possible, and are written as ‘thin wrappers’ that serve as specialised uses of other ‘ lower’ packages. Attending conferences revealed a clear trade-off between fully open source projects - enormous development teams that are harder to coordinate - and projects driven mainly by single institutions - better planned/directed development, but slower too.

Python’s unique strengths

I’m particularly impressed with the pragmatism around Python - the priority is ease of understanding, and this has grown an enormous community of contributors. This powerful community has produced libraries which enable writing in Python while passing execution to more difficult language(s) where better performance is available (e.g. NumPy calling C). The best of both worlds! These merits have allowed Python to enter ‘mainstream’ use in
scientific analysis, where unusually those writing scripts have limited resource to spare on becoming language experts. Here Python’s ease of learning and debugging shine in contrast to the original mainstream language: R.

Coordinating team software development

In 2022 I became our team’s ‘primary lead’ for Iris - our main software library. I am responsible for:

Since this is not a ‘dictatorship’ model, much of the above is about enabling the team to be mindful of these concerns and make decisions, perhaps by highlighting something during a discussion, or convening a workshop. I am essentially Iris’ ‘advocate’ within the team.