Polars.NET 0.3.1

Polars.NET

High-Performance, DataFrame Engine for .NET, powered by Rust & Apache Arrow. With cloud and deltalake features.

Supported Platforms: Windows (x64), Linux (x64/ARM64, glibc/musl), macOS (ARM64). Cloud: AWS, Azure and GCP Data Lake: Delta Lake

Why Polars.NET exists

This is the game I'd like to play: binding the lightning-fast Polars engine to the .NET ecosystem. And it brings a lot of fun.

• Polars.NET vs Python Ecosystem

  <picture> <source media="(prefers-color-scheme: dark)" srcset="assets/benchmark_python_dark.png"> <img alt="Polars.NET vs Python" src="assets/benchmark_python_light.png"> </picture>

• Speedup vs Legacy .NET

  <picture> <source media="(prefers-color-scheme: dark)" srcset="assets/benchmark_summary_dark.png"> <img alt="Speedup Summary" src="assets/benchmark_summary_light.png"> </picture>

Installation

C# Users:

dotnet add package Polars.NET 
# And then add the native runtime for your current environment:
dotnet add package Polars.NET.Native.win-x64

F# Users:

dotnet add package Polars.FSharp
# And then add the native runtime for your current environment:
dotnet add package Polars.NET.Native.win-x64

• Requirements: .NET 8+.
• Hardware: CPU with AVX2 support (x86-64-v3). Roughly Intel Haswell (2013+) or AMD Excavator (2015+). If you have AVX-512 supported CPU, please try to compile Rust core on your machine use RUSTFLAGS='-C target-cpu=native'

Quick Start

C# Example

using Polars.CSharp;
using static Polars.CSharp.Polars; // For Col(), Lit() helpers

// 1. Create a DataFrame
var data = new[] {
    new { Name = "Alice", Age = 25, Dept = "IT" },
    new { Name = "Bob", Age = 30, Dept = "HR" },
    new { Name = "Charlie", Age = 35, Dept = "IT" }
};
var df = DataFrame.From(data);

// 2. Filter & Aggregate
var res = df
    .Filter(Col("Age") > 28)
    .GroupBy("Dept")
    .Agg(
        Col("Age").Mean().Alias("AvgAge"),
        Col("Name").Count().Alias("Count")
    )
    .Sort("AvgAge", descending: true);

// 3. Output
res.Show();
// shape: (2, 3)
// ┌──────┬────────┬───────┐
// │ Dept ┆ AvgAge ┆ Count │
// │ ---  ┆ ---    ┆ ---   │
// │ str  ┆ f64    ┆ u32   │
// ╞══════╪════════╪═══════╡
// │ IT   ┆ 35.0   ┆ 1     │
// │ HR   ┆ 30.0   ┆ 1     │
// └──────┴────────┴───────┘

F# Example

open Polars.FSharp

// 1. Scan CSV (Lazy)
let lf = LazyFrame.ScanCsv "users.csv"

// 2. Transform Pipeline
let res = 
    lf
    |> pl.filterLazy (pl.col "age" .> pl.lit 28)
    |> pl.groupByLazy 
        [ pl.col "dept" ]
        [ 
            pl.col("age").Mean().Alias "AvgAge" 
            pl.col("name").Count().Alias "Count"
        ]
    |> pl.collect
    |> pl.sort ("AvgAge", false)

// 3. Output
res.Show()

Benchmark

• Benchmark Code

Architecture

3-Layer Architecture ensures API stability.

1. Hand-written Rust C ABI layer bridging .NET and Polars. (native_shim)
2. .NET Core layer for dirty works like unsafe ops, wrappers, LibraryImports. (Polars.NET.Core)
3. High level C# and F# API layer here. No unsafe blocks. (Polars.CSharp & Polars.FSharp)

Roadmap

• Expanded SQL and LINQ Support: Full coverage of Polars SQL capabilities (CTEs, Window Functions) to replace in-memory DataTable SQL queries. LINQ extension is under blueprinting.

• Cloud Support: Direct IO integration with AWS S3, Azure Blob Storage, and Data Lakes. ⇒ Done.

• Additional Data Lake Support: Add catalog feature.

• Documentation: Docs Here

Contributing

Contributions are welcome! Whether it's adding new expression mappings, improving documentation, or optimizing the FFI layer.

1. Fork the repo.

2. Create your feature branch.

3. Submit a Pull Request.

License

MIT License. See LICENSE for details.