/pe1/src/cs276/pe1/spell/KGramWithEditDistanceSpellingCorrector.java

package cs276.pe1.spell;

import java.util.List;
import java.util.Set;

import cs276.util.StringUtils;
import cs276.util.Counter;
import cs276.util.Counters;

public class KGramWithEditDistanceSpellingCorrector extends KGramSpellingCorrector {
    public enum ListCompare { 
        BASIC, //from the jaccard top 10, finds the one with the smallest edit distance (and highest jaccard score)
        TIEBREAKING, //uses word frequency to break ties
        NORMALIZE //Normalizes then multiplies score and edit distance
    };
    
    //Change this to change the type of corrections returned
    protected static ListCompare correctionsType = ListCompare.NORMALIZE;
	public KGramWithEditDistanceSpellingCorrector() {
        super();
	}

    protected Counter<String> editDistance(String word, List<String> potentialWords)
    {
        Counter<String> editDistance = new Counter<String>();
        for(String s:potentialWords)
            editDistance.incrementCount(s,StringUtils.levenshtein(word,s));
        return editDistance;
    }
    
    protected void reciprocal(Counter<String> target) {
		for (String key : target.keySet()) {
			target.setCount(key, 1.0/((double)target.getCount(key)));
		}
	}
    
	public List<String> corrections(String word) {
        Counter<String> scoredCounter = jaccardScore(word);
        List<String> firstPass = scoredCounter.topK(WL);
        
        if(correctionsType == ListCompare.BASIC||correctionsType == ListCompare.TIEBREAKING)
        {
            Counter<String> editDistance = editDistance(word,firstPass);
            Set<String> minKeys = Counters.keysAt(editDistance,Counters.min(editDistance));
            
            Counter<String> smallestEDJaccard = new Counter<String>();
            for(String s:minKeys)
                smallestEDJaccard.incrementCount(s,scoredCounter.getCount(s));
            if(correctionsType == ListCompare.TIEBREAKING)
            {
                Set<String> minKeys2 = Counters.keysAt(smallestEDJaccard,Counters.min(smallestEDJaccard));
                if(minKeys2.size()>1)
                {
                    Counter<String> tie = new Counter<String>();
                    for(String s:minKeys2)
                        tie.incrementCount(s,freq.getCount(s));
                    return tie.topK(WL);
                }
            }
            return smallestEDJaccard.topK(WL);
        }
        else if(correctionsType == ListCompare.NORMALIZE)
        {
            Counter<String>editDistance = editDistance(word,firstPass);
        
            Counters.retainTop(scoredCounter,WL);
            Counters.normalize(scoredCounter);
            Counters.normalize(editDistance);
        
            reciprocal(editDistance);
            Counters.multiplyInPlace(scoredCounter,editDistance);
        
            return scoredCounter.topK(WL);
        }
        return firstPass;
	}
}