source: src/main/java/agents/ai2014/group6/FrequencyAnalysisOpponentModel.java@ 61

package agents.ai2014.group6;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map.Entry;

import genius.core.Bid;
import genius.core.issue.Value;

public class FrequencyAnalysisOpponentModel implements IOpponentModel {
        
        HashMap<Integer,List<Value>> preferences;
        
        public FrequencyAnalysisOpponentModel() {
                preferences = new HashMap<Integer,List<Value>>();
        }

        @Override
        // Returns the value of an issue that is most often observed. 
        // If all values are observed an equal amount of times, then select the most recent value
        // If the issueId has not yet been observed, return null
        public Value getValue(Integer issueId) {
                List<Value> values = preferences.get(issueId);
                
                if(values == null) { 
                        // If no values have been learned for the issue, return null
                        return null;
                } else {
                        // Otherwise, search value with the highest frequency or most recent
                        int maxFreq = 0;
                        Value maxVal = null;
                        
                        for(Value v: values) {
                                int freq = Collections.frequency(values, v);
                                if(freq > maxFreq) {
                                        maxFreq = freq;
                                        maxVal = v;
                                }
                        }
                        
                        return maxVal;
                }
        }

        @Override
        public void learnWeights(Bid bid) {
                for(Entry<Integer, Value> issue : bid.getValues().entrySet()) {
                        if(!preferences.containsKey(issue.getKey()))
                                preferences.put(issue.getKey(), new ArrayList<Value>());
                                
                        preferences.get(issue.getKey()).add(issue.getValue());
                }
        }

}