How to Apply Custom Functions on Polars Groups (.group_by().apply())

· · June 6, 2026, 2 p.m.
Data Science 2026 apply groupBy Python data-processing Performance Optimization polars
Summary
This blog post discusses the performance issues of using .map_elements() in Polars and contrasts it with the faster .group_by().agg() method, ultimately suggesting the application of custom functions on grouped data using .group_by().apply().
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