polars

combined

High-performance DataFrame library for Python ETL, analytics, and pandas migration. It supports expression-based data manipulation with lazy query optimization, parallel execution, streaming out-of-core processing, Arrow interoperability, and optional GPU execution. Polars DataFrame library for high-performance data manipulation. Lazy/eager execution, expressions, I/O (CSV, Parquet, JSON), aggregations, joins, string/datetime ops, pandas interop. Use for Polars DataFrames or reading/writing Parquet files.

When to use

You need a faster in-memory DataFrame workflow than pandas for data that still fits in RAM.
You are building ETL, analytics, or transformation pipelines that benefit from lazy evaluation and parallel execution.
You want expression-based tabular operations on top of Apache Arrow semantics.

When not to use

Use this skill only when the task clearly matches the scope described above.
Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

Skill page

Conflict

The copies share a common core (expressions, lazy vs eager, basic I/O, group_by) but diverge significantly in scope and specific guidance. The K-Dense copy is a version-pinned (1.44.2) reference with specific installation commands and detailed mapping strategy explanations. The Vibe-Skills and agentic-awesome-skills copies are nearly identical, focusing on 'in-memory' use cases and providing a slightly different (simpler) explanation of window function mapping strategies. The brycewang-stanford copy is a 'meta-skill' that provides a decision tree and a table of reference files rather than inline code examples, and it includes specific version migration notes (e.g., `apply` to `map_elements`). Because the K-Dense copy has unique version-specific details and the brycewang copy has a unique structural approach (decision trees) and migration notes, no single copy is the 'authentic' procedure that the others merely reproduce. They represent different levels of abstraction and specific constraints.