source: trunk/EventBenchCore/src/de/ugoe/cs/eventbench/markov/HighOrderMarkovModel.java @ 12

package de.ugoe.cs.eventbench.markov;

import java.util.LinkedList;
import java.util.List;
import java.util.Random;

import de.ugoe.cs.eventbench.data.Event;
import de.ugoe.cs.eventbench.ppm.TrieBasedModel;

public class HighOrderMarkovModel extends TrieBasedModel {
        
        public HighOrderMarkovModel(int maxOrder, Random r) {
                super(maxOrder, r);
        }
                
        @Override
        protected double getProbability(List<Event<?>> context, Event<?> symbol) {
                double result = 0.0d;
                
                List<Event<?>> contextCopy = new LinkedList<Event<?>>(context);

        
                List<Event<?>> followers = trie.getFollowingSymbols(contextCopy);
                int sumCountFollowers = 0; // N(s\sigma')
                for( Event<?> follower : followers ) {
                        sumCountFollowers += trie.getCount(contextCopy, follower);
                }
                
                int countSymbol = trie.getCount(contextCopy, symbol);
                if( sumCountFollowers!=0 ) {
                        result = ((double) countSymbol / sumCountFollowers);
                }
                
                return result;
        }

}