This guide really is ground up. It introduced the central concepts in a simple way then built on those in subsequent chapters. Afterwards I felt I had a deep understanding of the design principles behind Polars. The author supplies a projects worth of Jupyter Notebooks to accompany each chapter with all examples in the text covered. The index was somewhat limited in that you couldnt look up all commands mentioned but you can obviously look up those in the Polars API documentation. If your picking up Polars I really recommend this book - text is excellent and the accompanying jupyter course beats any online course Ive looked at.