PyData Cardiff - July 2025

Hey Cardiff! 🚀 Ready to dive into the world of data science, Python, and all things analytics? Join us on Thursday, 31st July, at the iconic Hodge House for an evening of learning, networking, and inspiration. Whether you’re a seasoned data wizard or just starting your journey, this meetup is your chance to connect with fellow enthusiasts and soak up some seriously cool insights.
What’s on tap?

• Two guest talks from Marco Gorelli and James C Yarrow.
• A chance to mingle with some of Cardiff’s brightest minds and share tales.
• Real-world stories, cutting-edge techniques, and actionable takeaways to level up your data game.

Talks
Marco Gorelli - Creator and Maintainer of Narwhals
Ever tried passing a Polars Dataframe to a Data Science library and found that it.. just works? No errors, no panics, no noticeable overhead, just... results? This is becoming increasingly common in 2025, yet only 2 years ago, it was mostly unheard of. So, what changed? A large part of that answer is: Narwhals.
Narwhals is a lightweight compatibility layer between dataframe libraries which lets your code work seamlessly across Polars, Pandas, PySpark, DuckDB and more! It's not just a theoretical possibility: with approaximately 30 million monthly downloads and set as a required dependency of Altair, Bokeh, Marimo, Plotly, Shiny and more, it's clear that it's reshaping the Data Science landscape.
By the end of the talk, you'll understand why writing generic Dataframe code was such a headache (and is no longer such a pain), how Narwhals works and how its community operates, and how you can use it in your projects today. The talk will be technical yet accessible and light-hearted.

James C Yarrow, Senior Data Engineer at Future Publishing - Python and the Data Platform in 2025
This will be a walkthrough of the modern data platform, the capabilities and the challenges Python is solving and how other tools like Airflow and DBT play a role in the modern data platform.

Agenda (A rough idea of what to expect):

• 6:30 PM: Doors open + mingling (sparky conversations and Python trivia?)
• 7:00 PM: Introductions to the night
• 7:15 PM: Kickoff with the first talk with Marco.
• 8:00 PM: Interlude!
• 8:15 PM: The second talk with James.
• 9:00 PM: Optional Trip to the pub to continue talking about AI / Data

P.S. Follow us @pydatacardiff on x.com for speaker reveals, sneak peeks, and the occasional meme about pandas (the library kind).
#PyDataCardiff | Hosted at Hodge House
Let’s code, connect, and celebrate data together! 🐍✨

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Event organized by the PyData Cardiff Team.
Venue Sponsor by Future Publishing.
(thank you, legends!).