alcalyn / elo
Elo system with a reliability purpose
This package is not auto-updated.
Last update: 2024-11-09 17:40:24 UTC
README
Another Elo implementation in PHP ! But this one introduce a reliability purpose.
Reliability purpose
A history: You have a good player A which played many games and have a score of 2100 Elo. A new player B subscribe to the game website, so his Elo score is initialized to 1500. But in fact, he is a very good player, better than A, and beat him like crushing an ant.
The problem: New player B will win many Elo because he won against a 2100 Elo player. That's ok. But player A (2100 Elo) will lose many Elo because he lost against a 1500 Elo player, but in fact strongest.
The fact is that the new player Elo score is not reliable, so it should not impact others players Elo scores.
The solution: This library. It introduces a reliability coefficient (decimal between 0.0 and 1.0) for Elo A and Elo B.
Composer
Install via composer
{ "require": { "alcalyn/elo": "1.x" } }
Or download the library manually if you don't use composer.
Usage
- Instantiate a standard Elo system
use Alcalyn/Elo/EloSystem; $eloSystem = new EloSystem();
- Calculate updated Elo scores from old Elo
/** * A player with 1650 Elo beat another with 1920 */ $updatedElos = $eloSystem->calculate(1650, 1920, 1); print_r($updatedElos); /* Output: Array ( [0] => 1663.2084157978 [1] => 1906.7915842022 ) */
- Set reliability coefficient to Elo scores
/** * A player with 1907 Elo (1.0 reliability) * lose against a new player with 1500 (and reliability to 0.0) */ $updatedElos = $eloSystem->calculate(1907, 1500, 0, 1.0, 0.0); print_r($updatedElos); /* Output: Array ( [0] => 1907 [1] => 1514.5978664353 ) */
- Using method aliases for win, lose or draw
/** * Method Aliases */ $elo->win(2100, 1500, 1.0, 0.0); $elo->lose(2100, 1500, 1.0, 0.0); $elo->draw(2100, 1500, 1.0, 0.0);
- Instanciate a system with a different K factor (default is 16)
/** * Use a different K factor in your Elo system */ $eloSystemK32 = new EloSystem(32);
Detailled examples
A new player:
Player A has 2100 Elo, reliability 1.0
Player B has 1500 Elo, reliability 0.0
A wins: Expected result, so B loses a small amount of Elo, and A win nothing.
B wins: NOT expected result, so B wins a BIG amount of Elo, and A lose nothing.
A Elo score will not be updated when he plays versus a new player with an unreliable Elo score.
(And new player B should have its Elo reliability increased by something like 1/10 after every games until his reliability reaches 1)
$elo = new EloSystem(); /** * Result without reliability */ print_r($elo->lose(2100, 1500)); /* Output: Array ( [0] => 2084.4904548805 // lose -16 Elo [1] => 1515.5095451195 // win +16 Elo ) */ /** * Result with reliability */ print_r($elo->lose(2100, 1500, 1.0, 0.0)); /* Output: Array ( [0] => 2100 // don't lose Elo against new player [1] => 1515.5095451195 // win +16 Elo vs reliable Elo score ) */
Another example: two newbies players:
Player A has 1500 Elo, reliability 0.0
Player B has 1500 Elo, reliability 0.0
There is two new players, so their reliabilities are both 0.0: the algorithm takes them like if they were both 1.0.
And if player A had an Elo reliability equal to 0.4, and player B equal to 0.0, the algorithm adds them +0.6 so one of reliabilities reaches 1.0.
License
This project is under MIT Lisense