yutongamber/elopy

A python library for the Elo Rating System

EloPy

Please reccomend any functionality you think should be added!

A python library for the Elo Rating System. Right now it only supports 1 vs 1 games.

What is the Elo Rating System?

• The Elo Rating System (Elo) is a rating system used for rating players in games. Originally developed for chess by Arpad Elo, Elo has been applied to a large array of games.
• Each player is assigned a number as a rating. The system predicts the outcome of a match between two players by using an expected score formula (i.e. a player whose rating is 100 points greater than their opponent's is expected to win 64% of the time).
• Everytime a game is played, the Elo rating of the participants change depending on the outcome and the expected outcome. The winner takes points from the loser; the amount is determined by the players' scores and ratings
• A win is counts as a score of 1, loss is a score of 0, and draw is a score of 0.5

Calculations

If Player A has a rating of R_A and Player B a rating of R_B, the exact formula for Player A's score is:

And Player B's score is:

Supposing Player A was expected to score E_A points but actually scored S_A points. The formula for updating his/her rating is:

Right now the K factor is found by the number of player multiplied by 42 as a constant. Working on custom K factors.

Syntax when using EloPy

Creating your own implementation

from elopy import *

i = Implementation()

Adding and removing players

i.addPlayer("Hank") #default ranking is 1000
i.addPlayer("Bill",rating=900)

print i.getPlayerRating("Hank"), i.getPlayerRating("Bill")

i.removePlayer("Hank")

print i.getRatingList()

1000 900
900

Recording a match

i.recordMatch("Hank","Bill",winner="Hank")

print i.getRatingList()

i.recordMatch("Hank","Bill",winner="Bill")

print i.getRatingList()

i.recordMatch("Hank","Bill",draw=True)

print i.getRatingList()

[('Hank', 1030.2345400165577), ('Bill', 869.7654599834424)]
[('Hank', 970.1071401496504), ('Bill', 929.8928598503497)]
[('Hank', 965.2674016281943), ('Bill', 934.7325983718058)]