hoersamu / multi-elo

This package implements a multiplayer extension of the popular Elo rating system.

multi-elo

This package implements a multiplayer extension of the popular Elo rating system.

• Installation
• Example Usage
• Methodology
  • Traditional Elo ratings
  • Extension to multiplayer

This Package is based on djcunningham0s python implementation. For additional information, see his blog post on Towards Data Science (or try this link if you hit a paywall).

Installation

The package can be installed from GitHub or npm by using npm.

# npm
npm install multi-elo

# yarn
yarn add multi-elo

# pnpm
pnpm install multi-elo

# bun
bun install multi-elo

Import:

// ESM
import {} from "multi-elo";

// CommonJS
const {} = require("multi-elo");

Example Usage

The following example shows how to calculate updated Elo ratings after a matchup using the default settings in the package.

import { MultiElo } from 'multi-elo';

# player with 1200 rating beats a player with 1000 rating
MultiElo.getNewRatings([1200, 1000])
# [1207.68809835,  992.31190165]

# player with 900 rating beats player with 1000 rating
MultiElo.getNewRatings([900, 1000])
# [920.48207999, 979.51792001]

# 3-way matchup
MultiElo.getNewRatings([1200, 900, 1000])
#  [1208.34629612,  910.43382278,  981.21988111]

See demo.md for a more in-depth tutorial, including details on parameters that can be tuned in the Elo algorithm.

Methodology

For more Info on the methodology read djcunningham0s Readme.

Development

• Clone this repository
• Install latest LTS version of Node.js
• Enable Corepack using corepack enable
• Install dependencies using pnpm install
• Run interactive tests using pnpm dev

License

Made with 💛 by Samuel Höra

Published under MIT License.

multi-elo's Issues

Deprecation warning while using with NodeJS

Hi there! Here is the warning I'm getting, Not sure how to fix it.

(node:6929) [DEP0128] DeprecationWarning: Invalid 'main' field in '/Users/.........../node_modules/multi-elo/package.json' of 'lib/index.js'. Please either fix that or report it to the module author
(Use node --trace-deprecation ... to show where the warning was created)

Incorrect scoring with greater than 9 results

The issue is that the .sort() in the argsort function will by default use a string conversion so "11" sorts ahead of "9". I found this when trying to run

elo.getNewRatings([1688,1590,1581,1582,1550,1500,1465,1455,1435,1453,1432,1472,1526], [1,2,3,4,5,6,7,8,9,10,11,11,12]);

It fails the validation since there is not a zero score and no tie for last place. If you sort the results by numeric values it all works correctly.

basically just need

export const argsort = (arr: number[]) =>
  arr
    .map((element, index) => decor(element, index))
    .sort((a, b) => (a[0] - b[0]))
    .map((element) => undecor(element));

If you want to give me ability to create a branch/PR I'd be happy to put that change up for you.