Rayter is a program for generating player ratings from a number of games, with the results stored in a file.
pip install rayter
Rayter file format
The rayter file format is designed to be easily created by hand using a text editor. Here is an example for a file containing two games of Hearts:
score_type lowscore game 2011-12-24 22:00 Jessica 95 Hugo 77 Jonatan 89 Jakob 103 game 2011-12-24 23:19 Hugo 107 Jonatan 96 Peter 65 Jakob 70
score_type lowscore means that in this game the goal is to have as low score as possible. The options for score_type are lowscore and highscore (the default, if score_type is not specified).
Number of whitespace characters doesn't matter.
The format of the timestamp is year-month-day hour:minute, where hour is from 0 to 23. The timestamp is currently not used more than as an identifier of the game.
Every player starts with a rating of 1000. The sum of all ratings will always be 1000 * the number of players in the league. So if one player gets +60 rating in a game, and all other players lose rating, the sum of their rating change will be -60.
If a player with a rating of 1200 is playing against an opponent with a rating of 1000, the first player is expected to get 20% more points than the second one. That means that if the first player scores 240 points in the game, and the second player scores 200, the rating change of both players will be 0, since 240 divided by 200 equals 1200 divided by 1000.
Here are some results in a made-up card game:
game 2011-12-24 23:19 Dahlia 27 John 15 Ahmed 14 Lei 10 game 2011-12-25 21:12 John 23 Dahlia 10 Lei 4 Ahmed 4
After the first game, the ratings will look like this:
Name Games Rating Delta Dahlia 1 1032 32 John 1 995 -5 Ahmed 1 992 -8 Lei 1 980 -20
When the second game was played, the ratings changed to this:
Name Games Rating Delta John 2 1058 62 Dahlia 2 1029 -3 Ahmed 2 962 -30 Lei 2 951 -30
For more details see rater.py.