https://github.com/tomarrell/rust-elias-fano

Elias-Fano encoding implementation in Rust
https://github.com/tomarrell/rust-elias-fano

algorithm compression elias-fano encoding hacktoberfest inverted-index rust search-algorithm

Last synced: about 2 months ago
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Elias-Fano encoding implementation in Rust

• Host: GitHub
• URL: https://github.com/tomarrell/rust-elias-fano
• Owner: tomarrell
• License: mit
• Created: 2018-07-11T12:31:17.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2019-06-05T11:26:27.000Z (over 5 years ago)
• Last Synced: 2024-10-04T12:45:04.301Z (3 months ago)
• Topics: algorithm, compression, elias-fano, encoding, hacktoberfest, inverted-index, rust, search-algorithm
• Language: Rust
• Homepage:
• Size: 25.4 KB
• Stars: 29
• Watchers: 4
• Forks: 5
• Open Issues: 4
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Elias-Fano, in Rust

[![Build Status](https://img.shields.io/badge/crate-elias--fano-brightgreen.svg)](https://crates.io/crates/elias-fano)

[![Rust Docs](https://img.shields.io/badge/docs.rs-elias--fano-orange.svg)](https://docs.rs/elias-fano)

Elias-Fano encoding in Rust.

The Elias-Fano encoding scheme is a quasi-succinct compression method for monotonic integers using gap compression on a Bitset. It allows for decompression of a bit at any position in `O(1)` time complexity.

Being quasi-succinct, it is therefore almost as good as the best theoretical possible compression as determined by the [Shannon-Hartley](https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem) theorem.

This implementation is based largely on one written in Go by [Antonio Mallia](https://www.antoniomallia.it/), which can be found at his repository [amallia/go-ef](https://github.com/amallia/go-ef).

## Todo:

- [x] Tests

- [x] Example usage

- [ ] Benchmarks, comparison with other implementations

## Installation

Add the following line to your Cargo.toml:

```diff

[dependencies]

+ elias-fano = "1.1.0"

```

## Example Usage

```rust

extern crate elias_fano;

use elias_fano::EliasFano;

fn main() {

    let sorted_array = [0, 3, 40, 1000];

    let size = sorted_array.len();

    let mut ef = EliasFano::new(sorted_array[size - 1], size as u64);

    ef.compress(sorted_array.iter());

    println!("{}", ef.value()); // 1

    match ef.next() {

        Ok(val) => println!("Retrieved value: {}", val), // 3

        Err(error) => println!("Err: {}", error),        // Out of bounds

    }

    let _ = ef.next();

    println!("{}", ef.value()); // 40

    ef.reset();

    println!("{}", ef.value()); // 0

    let _ = ef.visit(3);

    println!("{}", ef.value()); // 1000

}

```

## License

MIT licensed, see LICENSE for more details.