fastembed 2.0.0

🍕 Features

Supports synchronous usage. No dependency on Tokio.
Uses @huggingface/tokenizers for blazing-fast encodings.
Supports batch embedddings with parallelism using Rayon.

The default embedding supports "query" and "passage" prefixes for the input text. The default model is Flag Embedding, which is top of the MTEB leaderboard.

🔍 Not looking for Rust?

Python 🐍: fastembed
Go 🐳: fastembed-go
JavaScript 🌐: fastembed-js

🤖 Models

🚀 Installation

Run the following command in your project directory:

cargo add fastembed

Or add the following line to your Cargo.toml:

fastembed = "2"

📖 Usage

use fastembed::{FlagEmbedding, InitOptions, EmbeddingModel, EmbeddingBase};

// With default InitOptions
let model: FlagEmbedding = FlagEmbedding::try_new(Default::default())?;

// With custom InitOptions
let model: FlagEmbedding = FlagEmbedding::try_new(InitOptions {
    model_name: EmbeddingModel::BGEBaseEN,
    show_download_message: true,
    ..Default::default()
})?;

let documents = vec![
    "passage: Hello, World!",
    "query: Hello, World!",
    "passage: This is an example passage.",
    // You can leave out the prefix but it's recommended
    "fastembed-rs is licensed under Apache  2.0"
    ];

 // Generate embeddings with the default batch size, 256
 let embeddings = model.embed(documents, None)?;

 println!("Embeddings length: {}", embeddings.len()); // -> Embeddings length: 4
 println!("Embedding dimension: {}", embeddings[0].len()); // -> Embedding dimension: 768

Supports passage and query embeddings for more accurate results

 // Generate embeddings for the passages
 // The texts are prefixed with "passage" for better results
 let passages = vec![
     "This is the first passage. It contains provides more context for retrieval.",
     "Here's the second passage, which is longer than the first one. It includes additional information.",
     "And this is the third passage, the longest of all. It contains several sentences and is meant for more extensive testing."
    ];

 let embeddings = model.passage_embed(passages, Some(1))?;

 println!("Passage embeddings length: {}", embeddings.len()); // -> Embeddings length: 3
 println!("Passage embedding dimension: {}", embeddings[0].len()); // -> Passage embedding dimension: 768

 // Generate embeddings for the query
 // The text is prefixed with "query" for better retrieval
 let query = "What is the answer to this generic question?";

 let query_embedding = model.query_embed(query)?;

 println!("Query embedding dimension: {}", query_embedding.len()); // -> Query embedding dimension: 768

🚒 Under the hood

Why fast?

It's important we justify the "fast" in FastEmbed. FastEmbed is fast because:

Quantized model weights
ONNX Runtime which allows for inference on CPU, GPU, and other dedicated runtimes