@Override
 public double idf(String word) {
   return docFrequencies.getCount(word);
 }
 @Override
 public void incrementDocCount(String word, double by) {
   docFrequencies.incrementCount(word, by);
 }
 @Override
 public void incrementCount(String word, double by) {
   wordFrequencies.incrementCount(word, by);
   if (wordFrequencies.getCount(word) >= minWordFrequency && vocabWords.indexOf(word) < 0)
     vocabWords.add(word);
 }
 @Override
 public double wordFrequency(String word) {
   return wordFrequencies.getCount(word);
 }