Elo rating calculator

This is a module and script to process a list of game results and produce player rankings based on the Elo algorithm. For more information about Elo, see https://secure.wikimedia.org/wikipedia/en/wiki/Elo_rating_system



USAGE

From terminal, type:
perl6 elo.pl

elo.pl will look for a file called "results.csv" (in the local directory from which it is called). It expects results to be in the format 

Player1:Player2:Score

Where "Score" is the score as far as Player1 is concerned. A victory of Bob over Alice looks like:

Alice:Bob:0

A draw looks like

Alice:Bob:.5

The players' elo ratings come out in elo_list.csv



USE AS MODULE

This application itself actually uses two components. The file elo.pm implements the calculations related to the elo algorithm and the file elo.pl does the processing, importing the module to process the calculations.

To use the module, install it where perl can see it, then use:

use Chess::elo;

sub expectedBoth ($p1, $p2)
sub expected ($p1, $p2)

These two functions above return the expected result when supplied with the elo scores of two players. expected() returns only one result - for player 1. expectedBoth() returns a list ($player1, $player2), letting you collected expected results from just one function.

sub elo ($p1, $p2, $score)
sub eloBoth ($p1, $p2, $score)

These two above return the new elo ranks after an event. They take the previous elo ranks and $score is the outcome. ie. 1 if player1 won, 0.5 for draw, 0 if player 2 won (ie. player 1 lost). As before, they return the new ranks of player 1 for elo(), and both for eloBoth().

sub eloK ($p1, $p2, $score, $k)
sub eloBothK ($p1, $p2, $score, $k)

These two functions work just as before, but allow the option of supplying a custom K factor.

sub eloN ($p1, $score, $k, $e)

The above function works like eloK(), but also allows for a custom expected result. (all previous functions make a call to expected().



TO DO

* Maybe add command-line arguments to allow input and output from differently named files.
* Maybe allow inputting of already established elo ratings.
(If you would like a feature/change/fix contact me)




Elo-Calculator is Copyright (C) 2011, Daniel Stojanov

LICENSE INFORMATION

This code is free software; you
can redistribute it and/or modify it under the terms of the
Artistic License 2.0. For details, see the full text of the
license in the file LICENSE.

This program is distributed in the hope that it will be
useful, but it is provided "as is" and without any express
or implied warranties. For details, see the full text of
the license in the file LICENSE.