User:Nfwu/ELO Sim

Used RR@H server code as reference. No licence - use and abuse.

Running the code as-is outputs ratings of bots A, B and C for this scenario:
A vs B = 25/75
A vs C = 75/25
B vs C = 25/75

Code:

package roborumble;

import java.util.*;

// There are faster ways of doing this,
// but I wanted to replicate the RR@H server as close as possible.
// 
// So, here's an inefficent ELO simulator.

class EnemyStat {
	double wins;
	int benemy; //Looks like "Number of Battles agains this enemy"
}

class RobotStats {

	RobotStats(String n){
		this(n, 1600);
	}
	RobotStats(String n, double r){
		scoremap = new HashMap<String, EnemyStat>();
		post = false;
		name = n;
		battles = 0;
		rating = r;
	}

	String name;
	int battles;
	double rating;
	boolean post;
	HashMap<String, EnemyStat> scoremap;
}

public class Test {
	private static final double min_score = 0.0;

	private static final double max_score = 1.0;

	private static final double rating_change = 3.0;

	static RobotStats[] stats;
	public static void main(String[] args){
		//stats = new RobotStats[4];
		stats = new RobotStats[3];

		stats[0] = new RobotStats("BotA 1.0");
		stats[1] = new RobotStats("BotB 1.0");
		stats[2] = new RobotStats("BotC 1.0");

		//POST EXPERIMENT
		//stats[3] = new RobotStats("Post", 2000);
		//stats[3].post = true;

		//A/B=25/75, A/C=75/25, BC=25/75
		int rand;
		for (int i=0;i<1000;i++){
			rand = (int)(Math.random() * 6.0);
			if (rand == 1){
				//battleResults(0, 24.5+Math.random(), 1, 74.5+Math.random());
				battleResults(0, 25, 1, 75);
			} else if (rand == 2){
				//battleResults(1, 74.5+Math.random(), 0, 24.5+Math.random());
				battleResults(1, 75, 0, 25);
			} else if (rand == 3){
				//battleResults(0, 74.5+Math.random(), 2, 24.5+Math.random());
				battleResults(0, 75, 2, 25);
			} else if (rand == 4){
				//battleResults(2, 24.5+Math.random(), 0, 74.5+Math.random());
				battleResults(2, 25, 0, 75);
			} else if (rand == 5){
				//battleResults(1, 49.5+Math.random(), 2, 49.5+Math.random());
				battleResults(1, 25, 2, 75);
			} else {
				//battleResults(2, 49.5+Math.random(), 1, 49.5+Math.random());
				battleResults(2, 75, 1, 25);
			}
			//battleResults((int)(Math.random()*3), 50, 3, 50); //FROM POST EXPERIMENT
		}

		for (int i=0;i<stats.length;i++){
			System.out.println(stats[i].name+" - Battles "+stats[i].battles+" - Rating "+stats[i].rating);
		}

	}
	static void battleResults(int fid, double fscore, int sid, double sscore){
	//Get stuff for first
		double real1 = fscore / (fscore + sscore);
		if (real1 == 1.0 || real1 == 0.0) return; //RR@H server does this
		EnemyStat es1 = null;
		es1 = stats[fid].scoremap.get(stats[sid].name); //First's enemy data of second
		double wins1 = real1; if (es1 != null) wins1 = es1.wins;
		int benemy1 = 0; if (es1 != null) benemy1 = es1.benemy;
	//Get stuff for second
		double real2 = 1.0 - real1;
		EnemyStat es2 = null;
		es2 = stats[sid].scoremap.get(stats[sid].name); //Second's enemy data of first
		double wins2 = real1; if (es2 != null) wins2 = es2.wins;
		int benemy2 = 0; if (es2 != null) benemy2 = es2.benemy;
	//Calculate EnemyStat differences
		wins1 = 0.7 * wins1 + 0.3 * real1;

		wins2 = 0.7 * wins2 + 0.3 * real2;
		benemy1++;
		benemy2++;
	//Store the EnemyStats away
		if (es1 == null) {
			es1 = new EnemyStat(); 
		}
		es1.wins = wins1;
		es1.benemy = benemy1;
		stats[fid].scoremap.put(stats[sid].name, es1); //First's enemy data of second
		if (es2 == null) {
			es2 = new EnemyStat(); 
		}
		es2.wins = wins2;
		es2.benemy = benemy2;
		stats[sid].scoremap.put(stats[fid].name, es2); //Second's enemy data of first

	//Calculate rating change, anchored to all the other bots.
		double change1 = 0;

		double change2 = 0;
		for (int i=0;i<stats.length;i++) {
			//selectedrating = stats[i].rating;

			//Do stuff for first
			if (fid != i){
				double expected = 1.0 / (1+Math.pow(20,(stats[i].rating-stats[fid].rating)/800)); 
				expected = Math.max(Math.min(expected,max_score),min_score);
				if (stats[fid].scoremap.get(stats[i].name) != null){
					double selectedwins = stats[fid].scoremap.get(stats[i].name).wins;
					selectedwins = Math.max(Math.min(selectedwins,max_score),min_score);

					change1 += rating_change * (selectedwins - expected);
				}
			}
			//Do stuff for second
			if (sid != i){
				double expected = 1.0 / (1+Math.pow(20,(stats[i].rating-stats[sid].rating)/800)); 
				expected = Math.max(Math.min(expected,max_score),min_score);
				if (stats[sid].scoremap.get(stats[i].name) != null){
					double selectedwins = stats[sid].scoremap.get(stats[i].name).wins;
					selectedwins = Math.max(Math.min(selectedwins,max_score),min_score);

					change2 += rating_change * (selectedwins - expected);
				}
			}
		}

		if (!stats[fid].post) stats[fid].rating += change1;
		if (!stats[sid].post) stats[sid].rating += change2;

		stats[fid].battles++;
		stats[sid].battles++;
	}
}