glicko2-lite

An implementation of the Glicko-2 rating algorithm written from scratch, with the goal being to provide less conveniences than glicko2js in favor of faster execution time.

Basically glicko2-lite does not keep track of anything for you. All it does is calculate new ratings. Once I reached the point where I was trying to calculate ratings for tens of thousands of players across tens of thousands of matches, glicko2js only got slower and slower as more matches were added. For my case at least, I was already saving rating information to a database so I had no need for the Player classes that glicko2js provides; all I really needed was the actual calculation of new ratings itself.

bench/index.js is a benchmark I wrote to demonstrate the difference in execution time. In the benchmark, I create 1,000 players, and have the first player play a match against each of the other 999 players. After each individual match, I calculate the new ratings of the first player and his opponent. The result:

$ node bench/index.js

Starting...
  2 tests completed.

  glicko2-lite x   102 ops/sec ±2.35% (69 runs sampled)
  glicko2js    x 11.53 ops/sec ±6.97% (32 runs sampled)

Example

var glicko2 = require('glicko2-lite');

// player A: 1500 rating, 350 rating deviation, and 0.06 volatility
// player B: 2000 rating, 70 rating deviation
// A loses to B
// new rating, rating deviation, and volatility:
glicko2(1500, 350, 0.06, [[2000, 70, 0]])
// => {
// =>   rating: 1467.5878493169462,
// =>   rd: 318.6617548537152,
// =>   vol: 0.059999457650202655
// => }

Installation

$ npm install glicko2-lite

API

var glicko2 = require('glicko2-lite');

glicko2(rating, rd, vol, matches, [options])

• rating (Number)
• rd (Number)
• vol (Number)
• matches (Array)
• options (Object)