New Book: Python Polars: The Definitive Guide Now Available
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We’re proud to share that Jeroen Janssens, Senior Developer Relations Engineer at Posit, has co-authored a new book titled Python Polars: The Definitive Guide, together with Thijs Nieuwdorp. The book is now available in both print and ebook formats and is an essential resource for anyone working with data in Python.
A Practical Guide to a Powerful Python Library
Polars is a fast and expressive DataFrame library designed for efficient data transformation, analysis, and visualization. In this hands-on guide, Jeroen and Thijs walk readers through Polars’ capabilities and show how to apply them to real-world tasks like data wrangling, building pipelines, and exploratory data analysis.
You don’t need prior experience with pandas to benefit from this book, though those familiar with pandas will find helpful comparisons that make the transition to Polars easier. The book is rich with practical examples and uses real datasets, all of which are available in a public GitHub repository.
What You’ll Learn
Python Polars: The Definitive Guide covers every aspect of working with Polars, including:
- Loading data from CSV, Parquet, databases, and cloud sources
- Understanding and building expressions, the core of every Polars query
- Using both eager and lazy APIs
- Handling complex data types like text, timestamps, and nested structures
- Visualizing data using Altair, hvPlot, plotnine, and Great Tables
- Extending Polars with Python functions and Rust plugins
- Leveraging GPU acceleration for even better performance
Praise for Python Polars: The Definitive Guide
The book has already garnered praise from key figures in the data science and engineering communities. Here’s what others have to say:
Ritchie Vink, Creator of Polars, shares:
Jeroen and Thijs have done an excellent job—not only teaching you the ins and outs of Polars but also helping you unlearn habits from other tools like pandas. They really bring out the power of expressions, which are key to using Polars effectively.
Wes McKinney, Creator of pandas and Principal Architect at Posit, adds:
Polars has become a rising star in the Python data ecosystem, showing what’s possible in a next-generation data frame library. Jeroen and Thijs have written a timely and essential resource to help you take advantage of everything Polars has to offer.
Hannes Mühleisen, Co-Creator of DuckDB, notes:
Polars has brought a ton of much-needed innovation to the data frame world with its much more streamlined API and efficient implementation. I greatly respect Jeroen’s commitment to teaching data science in an accessible way, and his book is a testament to this commitment.
Marnix van Lieshout and Bram Timmers, Data Scientists at Alliander, share their experience:
We were initially skeptical about migrating to Polars, but we soon experienced the speed and intuitiveness of its API. As Jeroen and Thijs worked late hours to make progress with their book, we directly benefited from the improvements in our pipeline.
Marco Gorelli, Senior Software Engineer at Quansight, says:
The depth that Jeroen and Thijs went into to produce this book is impressive. This is the best Polars book out there—whether you’re new to Polars or want to improve your understanding of it, I wholeheartedly recommend it.
These endorsements highlight the clear impact of this guide and how it is helping data professionals transition to Polars with confidence.
Who This Book Is For
Whether you’re a data analyst, engineer, or scientist, this book will help you write more efficient, scalable, and elegant data workflows in Python. It’s suitable for beginners in data science as well as seasoned professionals looking to improve their data processing pipelines.
Get Your Copy
To learn more about the book, download a sample chapter, or find out where to buy it, visit polarsguide.com. You’ll also get access to the book’s code and community resources.
Join Jeroen at posit::conf(2025)
Jeroen will lead a workshop on Polars at posit::conf(2025) this September in Atlanta. It’s a great opportunity to dive deeper into Polars and learn directly from one of the authors. In addition, Jeroen will do a book signing session. Keep an eye on the conference website for details as the event approaches.
JOIN JEROEN AT CONF — REGISTER TODAY!
At Posit, we’re thrilled to support Jeroen in sharing his expertise with the broader Python data community. Congratulations to both Jeroen and Thijs on this important milestone.
