private static Set<String> extractVocabulary(List<TaggedSentence> taggedSentences) {
Set<String> vocabulary = new HashSet<String>();
for (TaggedSentence taggedSentence : taggedSentences) {
List<String> words = taggedSentence.getWords();
vocabulary.addAll(words);
}
return vocabulary;
}
private static void labelTestSet(
POSTagger posTagger, List<TaggedSentence> testSentences, String path) throws Exception {
BufferedWriter writer = new BufferedWriter(new FileWriter(path));
for (TaggedSentence sentence : testSentences) {
List<String> words = sentence.getWords();
List<String> guessedTags = posTagger.tag(words);
for (int i = 0; i < words.size(); i++) {
writer.write(words.get(i) + "\t" + guessedTags.get(i) + "\n");
}
writer.write("\n");
}
writer.close();
}
private List<LabeledLocalTrigramContext> extractLabeledLocalTrigramContexts(
TaggedSentence taggedSentence) {
List<LabeledLocalTrigramContext> labeledLocalTrigramContexts =
new ArrayList<LabeledLocalTrigramContext>();
List<String> words =
new BoundedList<String>(taggedSentence.getWords(), START_WORD, STOP_WORD);
List<String> tags = new BoundedList<String>(taggedSentence.getTags(), START_TAG, STOP_TAG);
for (int position = 0; position <= taggedSentence.size() + 1; position++) {
labeledLocalTrigramContexts.add(
new LabeledLocalTrigramContext(
words,
position,
tags.get(position - 2),
tags.get(position - 1),
tags.get(position)));
}
return labeledLocalTrigramContexts;
}
private static void evaluateTagger(
POSTagger posTagger,
List<TaggedSentence> taggedSentences,
Set<String> trainingVocabulary,
boolean verbose) {
double numTags = 0.0;
double numTagsCorrect = 0.0;
double numUnknownWords = 0.0;
double numUnknownWordsCorrect = 0.0;
int numDecodingInversions = 0;
for (TaggedSentence taggedSentence : taggedSentences) {
List<String> words = taggedSentence.getWords();
List<String> goldTags = taggedSentence.getTags();
List<String> guessedTags = posTagger.tag(words);
for (int position = 0; position < words.size() - 1; position++) {
String word = words.get(position);
String goldTag = goldTags.get(position);
String guessedTag = guessedTags.get(position);
if (guessedTag.equals(goldTag)) numTagsCorrect += 1.0;
numTags += 1.0;
if (!trainingVocabulary.contains(word)) {
if (guessedTag.equals(goldTag)) numUnknownWordsCorrect += 1.0;
numUnknownWords += 1.0;
}
}
double scoreOfGoldTagging = posTagger.scoreTagging(taggedSentence);
double scoreOfGuessedTagging = posTagger.scoreTagging(new TaggedSentence(words, guessedTags));
if (scoreOfGoldTagging > scoreOfGuessedTagging) {
numDecodingInversions++;
if (verbose)
System.out.println(
"WARNING: Decoder suboptimality detected. Gold tagging has higher score than guessed tagging.");
}
if (verbose) System.out.println(alignedTaggings(words, goldTags, guessedTags, true) + "\n");
}
System.out.println(
"Tag Accuracy: "
+ (numTagsCorrect / numTags)
+ " (Unknown Accuracy: "
+ (numUnknownWordsCorrect / numUnknownWords)
+ ") Decoder Suboptimalities Detected: "
+ numDecodingInversions);
}