mirror of
https://github.com/TheRealOwenRees/echecsfrance.git
synced 2026-07-23 04:26:57 +00:00
Timothy Armes
87 lines
1.9 KiB
TypeScript
87 lines
1.9 KiB
TypeScript
import { clamp, last } from "lodash";
|
|
|
|
// Fide uses teh following table to establish the chance of winning based on the difference in elo.
|
|
// https://handbook.fide.com/chapter/B022017
|
|
|
|
const differenceToProbability: [
|
|
start: number,
|
|
end: number,
|
|
winChance: number,
|
|
][] = [
|
|
[0, 3, 0.5],
|
|
[4, 10, 0.51],
|
|
[11, 17, 0.52],
|
|
[18, 25, 0.53],
|
|
[26, 32, 0.54],
|
|
[33, 39, 0.55],
|
|
[40, 46, 0.56],
|
|
[47, 53, 0.57],
|
|
[54, 61, 0.58],
|
|
[62, 68, 0.59],
|
|
[69, 76, 0.6],
|
|
[77, 83, 0.61],
|
|
[84, 91, 0.62],
|
|
[92, 98, 0.63],
|
|
[99, 106, 0.64],
|
|
[107, 113, 0.65],
|
|
[114, 121, 0.66],
|
|
[122, 129, 0.67],
|
|
[130, 137, 0.68],
|
|
[138, 145, 0.69],
|
|
[146, 153, 0.7],
|
|
[154, 162, 0.71],
|
|
[163, 170, 0.72],
|
|
[171, 179, 0.73],
|
|
[180, 188, 0.74],
|
|
[189, 197, 0.75],
|
|
[198, 206, 0.76],
|
|
[207, 215, 0.77],
|
|
[216, 225, 0.78],
|
|
[226, 235, 0.79],
|
|
[236, 245, 0.8],
|
|
[246, 256, 0.81],
|
|
[257, 267, 0.82],
|
|
[268, 278, 0.83],
|
|
[279, 290, 0.84],
|
|
[291, 302, 0.85],
|
|
[303, 315, 0.86],
|
|
[316, 328, 0.87],
|
|
[329, 344, 0.88],
|
|
[345, 357, 0.89],
|
|
[358, 374, 0.9],
|
|
[375, 391, 0.91],
|
|
[392, 411, 0.92],
|
|
[412, 432, 0.93],
|
|
[433, 456, 0.94],
|
|
[457, 484, 0.95],
|
|
[485, 517, 0.96],
|
|
[518, 559, 0.97],
|
|
[560, 619, 0.98],
|
|
[620, 735, 0.99],
|
|
[736, 1000, 1],
|
|
];
|
|
|
|
export const getNewRating = (
|
|
rating: number,
|
|
opponentRating: number,
|
|
result: 1 | 0 | 0.5,
|
|
kFactor: number,
|
|
) => {
|
|
const differenceInElo = clamp(opponentRating - rating, -400, 400);
|
|
const tableRow = (differenceToProbability.find(
|
|
([start, end]) =>
|
|
Math.abs(differenceInElo) >= start && Math.abs(differenceInElo) <= end,
|
|
) ?? last(differenceToProbability)!)[2];
|
|
|
|
const probabilityOfWinning = differenceInElo < 0 ? tableRow : 1 - tableRow;
|
|
const delta =
|
|
Math.round(
|
|
kFactor * (result - probabilityOfWinning + Number.EPSILON) * 100,
|
|
) / 100;
|
|
|
|
return {
|
|
delta,
|
|
newRating: Math.round((rating + delta + Number.EPSILON) * 100) / 100,
|
|
};
|
|
};
|