polars

原文涵盖的主题

• Polars
• Overview
• Quick Start
• Installation and Basic Usage
• Core Concepts
• Expressions
• Lazy vs Eager Evaluation
• Common Operations

Polars is a lightning-fast DataFrame library for Python and Rust built on Apache Arrow. Work with Polars' expression-based API, lazy evaluation framework, and high-performance data manipulation capabilities for efficient data processing, pandas migration, and data pipeline optimization. Install Polars: Basic DataFrame creation and operations: Expressions are the fundamental building blocks of Polars operations. They describe transformations on data and can be composed, reused, and optimized. Key principles: Use pl.col("columnname") to reference columns Chain methods to build complex transformations Expressions are lazy and only execute within contexts (select, withcolumns, filter, groupby) Example: Eager (DataFrame): Operations execute immediately Lazy (LazyFrame): Operations build a query plan, optimized before execution When to use lazy: Working with large datasets Complex query pipelines When only some columns/rows are needed Performance is critical Benefits of lazy evaluation: Automatic query optimization Predicate pushdown Projection pushdown Parallel execution For detailed concepts, load references/coreconcepts.md. Select and manipulate columns: Filter rows by conditions: Add

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