https://github.com/frjnn/adqselect

Rust nth_element implementation that leverages Andrei Alexandrescu's Adaptive Quickselect algorithm.
https://github.com/frjnn/adqselect

nthelement order-statistics quickselect rust

Last synced: 6 months ago
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Rust nth_element implementation that leverages Andrei Alexandrescu's Adaptive Quickselect algorithm.

Host: GitHub
URL: https://github.com/frjnn/adqselect
Owner: frjnn
License: mit
Created: 2020-08-13T09:57:41.000Z (over 5 years ago)
Default Branch: master
Last Pushed: 2021-01-10T13:46:29.000Z (about 5 years ago)
Last Synced: 2025-03-27T05:13:00.404Z (11 months ago)
Topics: nthelement, order-statistics, quickselect, rust
Language: Rust
Homepage:
Size: 1.08 MB
Stars: 4
Watchers: 2
Forks: 1
Open Issues: 0
Metadata Files:
- Readme: README.md
- License: LICENSE

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README

# adqselect

[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
[![frjnn](https://circleci.com/gh/frjnn/adqselect.svg?style=shield)](https://app.circleci.com/pipelines/github/frjnn/adqselect)
[![codecov](https://codecov.io/gh/frjnn/adqselect/branch/master/graph/badge.svg)](https://codecov.io/gh/frjnn/adqselect)

A lightweight crate that brings to Rust an `nth_element` implementation that leverages Andrei Alexandrescu's __adaptive quickselect__ algorithm. Also available on [crates.io](https://crates.io/crates/adqselect).

## Installation

Be sure that your `Cargo.toml` looks somewhat like this:
```toml
[dependencies]
adqselect = "0.1.3"
```
## Usage

Bring the crate into scope:

```rust
extern crate adqselect;

use adqselect::nth_element;
```
then simply call `nth_element` on a vector.

```rust
let mut v = vec![10, 7, 9, 7, 2, 8, 8, 1, 9, 4];
nth_element(&mut v, 3, &mut Ord::cmp);

assert_eq!(v[3], 7);
```

This implementation also handles generic data types as long as they satisfy the `PartialEq` and `PartialOrd` traits.

## Implementation

Link to the [original paper: Fast Deterministic Selection](https://arxiv.org/abs/1606.00484) by Andrei Alexandrescu.

## Performance

The algorithm is based on a refined version of Median of Medians and it guarantees linear deterministic time complexity.

## Benchmarks

Here are some benchmarks against other crates: [floydrivest](https://crates.io/crates/floydrivest), [order-stat](https://crates.io/crates/order-stat), [kth](https://crates.io/crates/kth) and [pdqselect](https://crates.io/crates/pdqselect).

Results

Violin Plot

This chart shows the relationship between function/parameter and iteration time. The thickness of the shaded
region indicates the probability that a measurement of the given function/parameter would take a particular
length of time.