ELO Rating System实例

package ELO_Rating_System; // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 2 of the License, or // (at your option) any later version. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU Library General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. import java.util.*; public class EloRating { public static final int[] RATINGS = { 0, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600 }; public static final int INITIAL = 1400; //initial rating for all users public static final int PROVISIONAL = 200; //may consider 200 points as a range for the ratings /** This is the maximum number of points up for grabs in a game. */ public static final int K_MAX = 32; //ratings<2000 public static final int K_MID = 20; //ratings>=2000 && ratings<=2400 public static final int K_MIN = 10; //ratings>2400 public static final double WIN = 1; public static final double LOSE = 0; public static final double EQU = 0.5; //no one win or lose public static String[] comName = {"Jimmy","Tom","Sherrly"}; public static int[] comRating = {2050,1270,1550}; public static double[] comScore = {EQU,WIN,WIN}; public static String[] compName = {"Jemmy","Lin","Fisher","Kobe","Yang","Aliy","Kitty", "Quatras","Yums","China","Jason"}; public static int[] compRating = {2500,2480,2430,2400,2375,2365,2335,2320,2300,2280,2260}; public static double[] compScore = {LOSE,LOSE,LOSE,LOSE,LOSE,LOSE,WIN,WIN,WIN,WIN,WIN}; public static Competitor[] initialize(String[] str,int[] ratings,double[] scores){ Competitor[] com = new Competitor[str.length]; int i=0; for(;i<str.length;i++) com[i]=new Competitor(str[i],ratings[i], scores[i]); return com; } /** * P(ratings[1]-ratings[0]) * Expected chance player[1] will beat player[0] */ public static double expectancy(User one,Competitor[] opponents) { int diff=0; for(int i=0;i<opponents.length;i++){ double probability = 1.0/(1.0+Math.pow(10.0,(opponents[i].rating-one.rating)/400.0)); System.out.println("\n"+probability); diff+=probability; } return diff; } /** * Expected number of points won by { player[0], player[1] } if they were * to win a match between the 2. */ public static double expectedRating(int k,User one,Competitor[] opponents) { double ex = expectancy(one,opponents); double totalScore=0; for(int i=0;i<opponents.length;i++) totalScore+=opponents[i].score; return one.rating+k*(totalScore-ex); } public static void main(String[] args){ User pan = new User("pan",1650); Competitor[] comp = initialize(comName, comRating, comScore); System.out.println("Test one result: "+expectedRating(K_MIN,pan,comp)); User cris = new User("cris",2350); Competitor[] comp2 = initialize(compName,compRating,compScore); System.out.println("Test two result: "+expectedRating(K_MAX,cris,comp2)); } }