https://github.com/tlhunter/node-arpad

An implementation of the ELO Rating System
https://github.com/tlhunter/node-arpad

Last synced: 25 days ago
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An implementation of the ELO Rating System

• Host: GitHub
• URL: https://github.com/tlhunter/node-arpad
• Owner: tlhunter
• Created: 2014-08-21T07:25:16.000Z (about 10 years ago)
• Default Branch: master
• Last Pushed: 2020-11-13T06:20:11.000Z (almost 4 years ago)
• Last Synced: 2024-09-14T09:08:40.744Z (about 2 months ago)
• Language: JavaScript
• Homepage: https://www.npmjs.org/package/arpad
• Size: 26.4 KB
• Stars: 96
• Watchers: 4
• Forks: 15
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Arpad: ELO Rating System for Node.js

This is an implementation of [ELO](http://en.wikipedia.org/wiki/Elo_rating_system) for Node.js (ELO is named after Arpad Elo, hence the package name).

This module is heavily tested and has many features used in real-world ELO situations.

## Installation

```bash

$ npm install arpad

```

## Simple Usage

This is a fairly simple example showing the most common usage for Arpad:

```javascript

const Elo = require('arpad');

const elo = new Elo();

let alice = 1_600;

let bob = 1_300;

let new_alice = elo.newRatingIfWon(alice, bob);

console.log("Alice's new rating if she won:", new_alice); // 1,605

let new_bob = elo.newRatingIfWon(bob, alice);

console.log("Bob's new rating if he won:", new_bob); // 1,327

```

## Complex Usage

This is a more complex example, making use of K-factor tables and score values:

```javascript

const Elo = require('arpad');

const uscf = {

  default: 32,

  2100: 24,

  2400: 16

};

const min_score = 100;

const max_score = 10_000;

const elo = new Elo(uscf, min_score, max_score);

let alice = 2_090;

let bob = 2_700;

let odds_alice_wins = elo.expectedScore(alice, bob);

console.log("The odds of Alice winning are about:", odds_alice_wins); // 0.029

alice = elo.newRating(odds_alice_wins, 1.0, alice);

console.log("Alice's new rating after she won:", alice); // 2121

odds_alice_wins = elo.expectedScore(alice, bob);

console.log("The odds of Alice winning again are about:", odds_alice_wins); // 0.034

alice = elo.newRating(odds_alice_wins, 1.0, alice);

console.log("Alice's new rating if she won again:", alice); // 2144

```

## Running Tests

If you'd like to contribute be sure to run `npm install` to get the required packages and then make changes.

Afterwards simply run the tests.

If everything passes your Pull Request should be ready.

```bash

$ npm test

```

## License

MIT