public static void main(String[] args) throws Exception {
// Parse command line flags and arguments
Map<String, String> argMap = CommandLineUtils.simpleCommandLineParser(args);
// Set up default parameters and settings
String basePath = ".";
boolean verbose = false;
// Update defaults using command line specifications
// The path to the assignment data
if (argMap.containsKey("-path")) {
basePath = argMap.get("-path");
}
System.out.println("Using base path: " + basePath);
// Whether or not to print the individual errors.
if (argMap.containsKey("-verbose")) {
verbose = true;
}
// Read in data
System.out.print("Loading training sentences...");
List<TaggedSentence> trainTaggedSentences =
readTaggedSentences(basePath + "/en-wsj-train.pos", true);
Set<String> trainingVocabulary = extractVocabulary(trainTaggedSentences);
System.out.println("done.");
System.out.print("Loading in-domain dev sentences...");
List<TaggedSentence> devInTaggedSentences =
readTaggedSentences(basePath + "/en-wsj-dev.pos", true);
System.out.println("done.");
System.out.print("Loading out-of-domain dev sentences...");
List<TaggedSentence> devOutTaggedSentences =
readTaggedSentences(basePath + "/en-web-weblogs-dev.pos", true);
System.out.println("done.");
System.out.print("Loading out-of-domain blind test sentences...");
List<TaggedSentence> testSentences =
readTaggedSentences(basePath + "/en-web-test.blind", false);
System.out.println("done.");
// Construct tagger components
// TODO : improve on the MostFrequentTagScorer
LocalTrigramScorer localTrigramScorer = new MostFrequentTagScorer(false);
// TODO : improve on the GreedyDecoder
TrellisDecoder<State> trellisDecoder = new GreedyDecoder<State>();
// Train tagger
POSTagger posTagger = new POSTagger(localTrigramScorer, trellisDecoder);
posTagger.train(trainTaggedSentences);
// Optionally tune hyperparameters on dev data
posTagger.validate(devInTaggedSentences);
// Test tagger
System.out.println("Evaluating on in-domain data:.");
evaluateTagger(posTagger, devInTaggedSentences, trainingVocabulary, verbose);
System.out.println("Evaluating on out-of-domain data:.");
evaluateTagger(posTagger, devOutTaggedSentences, trainingVocabulary, verbose);
labelTestSet(posTagger, testSentences, basePath + "/en-web-test.tagged");
}
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);
}
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();
}