public void advance() { boolean[] temp = inStatePrev; inStatePrev = inStateNext; inStateNext = temp; Arrays.fill(inStateNext, false); for (int state = 0; state < numStates; state++) { if (inStatePrev[state] && loopState[state]) { inStateNext[state] = true; } } }
public static Tree copyHelper(Tree t, Map<Tree, Tree> newToOld, Map<Tree, Tree> oldToNew) { Tree[] kids = t.children(); Tree[] newKids = new Tree[kids.length]; for (int i = 0, n = kids.length; i < n; i++) { newKids[i] = copyHelper(kids[i], newToOld, oldToNew); } TreeFactory tf = t.treeFactory(); if (kids.length == 0) { Tree newLeaf = tf.newLeaf(t.label()); newToOld.put(newLeaf, t); oldToNew.put(newLeaf, t); return newLeaf; } Tree newNode = tf.newTreeNode(t.label(), Arrays.asList(newKids)); newToOld.put(newNode, t); oldToNew.put(t, newNode); return newNode; }
public static void main(String[] args) { Options op = new Options(new EnglishTreebankParserParams()); // op.tlpParams may be changed to something else later, so don't use it till // after options are parsed. System.out.println("Currently " + new Date()); System.out.print("Invoked with arguments:"); for (String arg : args) { System.out.print(" " + arg); } System.out.println(); String path = "/u/nlp/stuff/corpora/Treebank3/parsed/mrg/wsj"; int trainLow = 200, trainHigh = 2199, testLow = 2200, testHigh = 2219; String serializeFile = null; int i = 0; while (i < args.length && args[i].startsWith("-")) { if (args[i].equalsIgnoreCase("-path") && (i + 1 < args.length)) { path = args[i + 1]; i += 2; } else if (args[i].equalsIgnoreCase("-train") && (i + 2 < args.length)) { trainLow = Integer.parseInt(args[i + 1]); trainHigh = Integer.parseInt(args[i + 2]); i += 3; } else if (args[i].equalsIgnoreCase("-test") && (i + 2 < args.length)) { testLow = Integer.parseInt(args[i + 1]); testHigh = Integer.parseInt(args[i + 2]); i += 3; } else if (args[i].equalsIgnoreCase("-serialize") && (i + 1 < args.length)) { serializeFile = args[i + 1]; i += 2; } else if (args[i].equalsIgnoreCase("-tLPP") && (i + 1 < args.length)) { try { op.tlpParams = (TreebankLangParserParams) Class.forName(args[i + 1]).newInstance(); } catch (ClassNotFoundException e) { System.err.println("Class not found: " + args[i + 1]); } catch (InstantiationException e) { System.err.println("Couldn't instantiate: " + args[i + 1] + ": " + e.toString()); } catch (IllegalAccessException e) { System.err.println("illegal access" + e); } i += 2; } else if (args[i].equals("-encoding")) { // sets encoding for TreebankLangParserParams op.tlpParams.setInputEncoding(args[i + 1]); op.tlpParams.setOutputEncoding(args[i + 1]); i += 2; } else { i = op.setOptionOrWarn(args, i); } } // System.out.println(tlpParams.getClass()); TreebankLanguagePack tlp = op.tlpParams.treebankLanguagePack(); Train.sisterSplitters = new HashSet(Arrays.asList(op.tlpParams.sisterSplitters())); // BinarizerFactory.TreeAnnotator.setTreebankLang(tlpParams); PrintWriter pw = op.tlpParams.pw(); Test.display(); Train.display(); op.display(); op.tlpParams.display(); // setup tree transforms Treebank trainTreebank = op.tlpParams.memoryTreebank(); MemoryTreebank testTreebank = op.tlpParams.testMemoryTreebank(); // Treebank blippTreebank = ((EnglishTreebankParserParams) tlpParams).diskTreebank(); // String blippPath = "/afs/ir.stanford.edu/data/linguistic-data/BLLIP-WSJ/"; // blippTreebank.loadPath(blippPath, "", true); Timing.startTime(); System.err.print("Reading trees..."); testTreebank.loadPath(path, new NumberRangeFileFilter(testLow, testHigh, true)); if (Test.increasingLength) { Collections.sort(testTreebank, new TreeLengthComparator()); } trainTreebank.loadPath(path, new NumberRangeFileFilter(trainLow, trainHigh, true)); Timing.tick("done."); System.err.print("Binarizing trees..."); TreeAnnotatorAndBinarizer binarizer = null; if (!Train.leftToRight) { binarizer = new TreeAnnotatorAndBinarizer(op.tlpParams, op.forceCNF, !Train.outsideFactor(), true); } else { binarizer = new TreeAnnotatorAndBinarizer( op.tlpParams.headFinder(), new LeftHeadFinder(), op.tlpParams, op.forceCNF, !Train.outsideFactor(), true); } CollinsPuncTransformer collinsPuncTransformer = null; if (Train.collinsPunc) { collinsPuncTransformer = new CollinsPuncTransformer(tlp); } TreeTransformer debinarizer = new Debinarizer(op.forceCNF); List<Tree> binaryTrainTrees = new ArrayList<Tree>(); if (Train.selectiveSplit) { Train.splitters = ParentAnnotationStats.getSplitCategories( trainTreebank, Train.tagSelectiveSplit, 0, Train.selectiveSplitCutOff, Train.tagSelectiveSplitCutOff, op.tlpParams.treebankLanguagePack()); if (Train.deleteSplitters != null) { List<String> deleted = new ArrayList<String>(); for (String del : Train.deleteSplitters) { String baseDel = tlp.basicCategory(del); boolean checkBasic = del.equals(baseDel); for (Iterator<String> it = Train.splitters.iterator(); it.hasNext(); ) { String elem = it.next(); String baseElem = tlp.basicCategory(elem); boolean delStr = checkBasic && baseElem.equals(baseDel) || elem.equals(del); if (delStr) { it.remove(); deleted.add(elem); } } } System.err.println("Removed from vertical splitters: " + deleted); } } if (Train.selectivePostSplit) { TreeTransformer myTransformer = new TreeAnnotator(op.tlpParams.headFinder(), op.tlpParams); Treebank annotatedTB = trainTreebank.transform(myTransformer); Train.postSplitters = ParentAnnotationStats.getSplitCategories( annotatedTB, true, 0, Train.selectivePostSplitCutOff, Train.tagSelectivePostSplitCutOff, op.tlpParams.treebankLanguagePack()); } if (Train.hSelSplit) { binarizer.setDoSelectiveSplit(false); for (Tree tree : trainTreebank) { if (Train.collinsPunc) { tree = collinsPuncTransformer.transformTree(tree); } // tree.pennPrint(tlpParams.pw()); tree = binarizer.transformTree(tree); // binaryTrainTrees.add(tree); } binarizer.setDoSelectiveSplit(true); } for (Tree tree : trainTreebank) { if (Train.collinsPunc) { tree = collinsPuncTransformer.transformTree(tree); } tree = binarizer.transformTree(tree); binaryTrainTrees.add(tree); } if (Test.verbose) { binarizer.dumpStats(); } List<Tree> binaryTestTrees = new ArrayList<Tree>(); for (Tree tree : testTreebank) { if (Train.collinsPunc) { tree = collinsPuncTransformer.transformTree(tree); } tree = binarizer.transformTree(tree); binaryTestTrees.add(tree); } Timing.tick("done."); // binarization BinaryGrammar bg = null; UnaryGrammar ug = null; DependencyGrammar dg = null; // DependencyGrammar dgBLIPP = null; Lexicon lex = null; // extract grammars Extractor bgExtractor = new BinaryGrammarExtractor(); // Extractor bgExtractor = new SmoothedBinaryGrammarExtractor();//new BinaryGrammarExtractor(); // Extractor lexExtractor = new LexiconExtractor(); // Extractor dgExtractor = new DependencyMemGrammarExtractor(); Extractor dgExtractor = new MLEDependencyGrammarExtractor(op); if (op.doPCFG) { System.err.print("Extracting PCFG..."); Pair bgug = null; if (Train.cheatPCFG) { List allTrees = new ArrayList(binaryTrainTrees); allTrees.addAll(binaryTestTrees); bgug = (Pair) bgExtractor.extract(allTrees); } else { bgug = (Pair) bgExtractor.extract(binaryTrainTrees); } bg = (BinaryGrammar) bgug.second; bg.splitRules(); ug = (UnaryGrammar) bgug.first; ug.purgeRules(); Timing.tick("done."); } System.err.print("Extracting Lexicon..."); lex = op.tlpParams.lex(op.lexOptions); lex.train(binaryTrainTrees); Timing.tick("done."); if (op.doDep) { System.err.print("Extracting Dependencies..."); binaryTrainTrees.clear(); // dgBLIPP = (DependencyGrammar) dgExtractor.extract(new // ConcatenationIterator(trainTreebank.iterator(),blippTreebank.iterator()),new // TransformTreeDependency(tlpParams,true)); DependencyGrammar dg1 = (DependencyGrammar) dgExtractor.extract( trainTreebank.iterator(), new TransformTreeDependency(op.tlpParams, true)); // dgBLIPP=(DependencyGrammar)dgExtractor.extract(blippTreebank.iterator(),new // TransformTreeDependency(tlpParams)); // dg = (DependencyGrammar) dgExtractor.extract(new // ConcatenationIterator(trainTreebank.iterator(),blippTreebank.iterator()),new // TransformTreeDependency(tlpParams)); // dg=new DependencyGrammarCombination(dg1,dgBLIPP,2); // dg = (DependencyGrammar) dgExtractor.extract(binaryTrainTrees); //uses information whether // the words are known or not, discards unknown words Timing.tick("done."); // System.out.print("Extracting Unknown Word Model..."); // UnknownWordModel uwm = (UnknownWordModel)uwmExtractor.extract(binaryTrainTrees); // Timing.tick("done."); System.out.print("Tuning Dependency Model..."); dg.tune(binaryTestTrees); // System.out.println("TUNE DEPS: "+tuneDeps); Timing.tick("done."); } BinaryGrammar boundBG = bg; UnaryGrammar boundUG = ug; GrammarProjection gp = new NullGrammarProjection(bg, ug); // serialization if (serializeFile != null) { System.err.print("Serializing parser..."); LexicalizedParser.saveParserDataToSerialized( new ParserData(lex, bg, ug, dg, Numberer.getNumberers(), op), serializeFile); Timing.tick("done."); } // test: pcfg-parse and output ExhaustivePCFGParser parser = null; if (op.doPCFG) { parser = new ExhaustivePCFGParser(boundBG, boundUG, lex, op); } ExhaustiveDependencyParser dparser = ((op.doDep && !Test.useFastFactored) ? new ExhaustiveDependencyParser(dg, lex, op) : null); Scorer scorer = (op.doPCFG ? new TwinScorer(new ProjectionScorer(parser, gp), dparser) : null); // Scorer scorer = parser; BiLexPCFGParser bparser = null; if (op.doPCFG && op.doDep) { bparser = (Test.useN5) ? new BiLexPCFGParser.N5BiLexPCFGParser( scorer, parser, dparser, bg, ug, dg, lex, op, gp) : new BiLexPCFGParser(scorer, parser, dparser, bg, ug, dg, lex, op, gp); } LabeledConstituentEval pcfgPE = new LabeledConstituentEval("pcfg PE", true, tlp); LabeledConstituentEval comboPE = new LabeledConstituentEval("combo PE", true, tlp); AbstractEval pcfgCB = new LabeledConstituentEval.CBEval("pcfg CB", true, tlp); AbstractEval pcfgTE = new AbstractEval.TaggingEval("pcfg TE"); AbstractEval comboTE = new AbstractEval.TaggingEval("combo TE"); AbstractEval pcfgTEnoPunct = new AbstractEval.TaggingEval("pcfg nopunct TE"); AbstractEval comboTEnoPunct = new AbstractEval.TaggingEval("combo nopunct TE"); AbstractEval depTE = new AbstractEval.TaggingEval("depnd TE"); AbstractEval depDE = new AbstractEval.DependencyEval("depnd DE", true, tlp.punctuationWordAcceptFilter()); AbstractEval comboDE = new AbstractEval.DependencyEval("combo DE", true, tlp.punctuationWordAcceptFilter()); if (Test.evalb) { EvalB.initEVALBfiles(op.tlpParams); } // int[] countByLength = new int[Test.maxLength+1]; // use a reflection ruse, so one can run this without needing the tagger // edu.stanford.nlp.process.SentenceTagger tagger = (Test.preTag ? new // edu.stanford.nlp.process.SentenceTagger("/u/nlp/data/tagger.params/wsj0-21.holder") : null); SentenceProcessor tagger = null; if (Test.preTag) { try { Class[] argsClass = new Class[] {String.class}; Object[] arguments = new Object[] {"/u/nlp/data/pos-tagger/wsj3t0-18-bidirectional/train-wsj-0-18.holder"}; tagger = (SentenceProcessor) Class.forName("edu.stanford.nlp.tagger.maxent.MaxentTagger") .getConstructor(argsClass) .newInstance(arguments); } catch (Exception e) { System.err.println(e); System.err.println("Warning: No pretagging of sentences will be done."); } } for (int tNum = 0, ttSize = testTreebank.size(); tNum < ttSize; tNum++) { Tree tree = testTreebank.get(tNum); int testTreeLen = tree.yield().size(); if (testTreeLen > Test.maxLength) { continue; } Tree binaryTree = binaryTestTrees.get(tNum); // countByLength[testTreeLen]++; System.out.println("-------------------------------------"); System.out.println("Number: " + (tNum + 1)); System.out.println("Length: " + testTreeLen); // tree.pennPrint(pw); // System.out.println("XXXX The binary tree is"); // binaryTree.pennPrint(pw); // System.out.println("Here are the tags in the lexicon:"); // System.out.println(lex.showTags()); // System.out.println("Here's the tagnumberer:"); // System.out.println(Numberer.getGlobalNumberer("tags").toString()); long timeMil1 = System.currentTimeMillis(); Timing.tick("Starting parse."); if (op.doPCFG) { // System.err.println(Test.forceTags); if (Test.forceTags) { if (tagger != null) { // System.out.println("Using a tagger to set tags"); // System.out.println("Tagged sentence as: " + // tagger.processSentence(cutLast(wordify(binaryTree.yield()))).toString(false)); parser.parse(addLast(tagger.processSentence(cutLast(wordify(binaryTree.yield()))))); } else { // System.out.println("Forcing tags to match input."); parser.parse(cleanTags(binaryTree.taggedYield(), tlp)); } } else { // System.out.println("XXXX Parsing " + binaryTree.yield()); parser.parse(binaryTree.yield()); } // Timing.tick("Done with pcfg phase."); } if (op.doDep) { dparser.parse(binaryTree.yield()); // Timing.tick("Done with dependency phase."); } boolean bothPassed = false; if (op.doPCFG && op.doDep) { bothPassed = bparser.parse(binaryTree.yield()); // Timing.tick("Done with combination phase."); } long timeMil2 = System.currentTimeMillis(); long elapsed = timeMil2 - timeMil1; System.err.println("Time: " + ((int) (elapsed / 100)) / 10.00 + " sec."); // System.out.println("PCFG Best Parse:"); Tree tree2b = null; Tree tree2 = null; // System.out.println("Got full best parse..."); if (op.doPCFG) { tree2b = parser.getBestParse(); tree2 = debinarizer.transformTree(tree2b); } // System.out.println("Debinarized parse..."); // tree2.pennPrint(); // System.out.println("DepG Best Parse:"); Tree tree3 = null; Tree tree3db = null; if (op.doDep) { tree3 = dparser.getBestParse(); // was: but wrong Tree tree3db = debinarizer.transformTree(tree2); tree3db = debinarizer.transformTree(tree3); tree3.pennPrint(pw); } // tree.pennPrint(); // ((Tree)binaryTrainTrees.get(tNum)).pennPrint(); // System.out.println("Combo Best Parse:"); Tree tree4 = null; if (op.doPCFG && op.doDep) { try { tree4 = bparser.getBestParse(); if (tree4 == null) { tree4 = tree2b; } } catch (NullPointerException e) { System.err.println("Blocked, using PCFG parse!"); tree4 = tree2b; } } if (op.doPCFG && !bothPassed) { tree4 = tree2b; } // tree4.pennPrint(); if (op.doDep) { depDE.evaluate(tree3, binaryTree, pw); depTE.evaluate(tree3db, tree, pw); } TreeTransformer tc = op.tlpParams.collinizer(); TreeTransformer tcEvalb = op.tlpParams.collinizerEvalb(); Tree tree4b = null; if (op.doPCFG) { // System.out.println("XXXX Best PCFG was: "); // tree2.pennPrint(); // System.out.println("XXXX Transformed best PCFG is: "); // tc.transformTree(tree2).pennPrint(); // System.out.println("True Best Parse:"); // tree.pennPrint(); // tc.transformTree(tree).pennPrint(); pcfgPE.evaluate(tc.transformTree(tree2), tc.transformTree(tree), pw); pcfgCB.evaluate(tc.transformTree(tree2), tc.transformTree(tree), pw); if (op.doDep) { comboDE.evaluate((bothPassed ? tree4 : tree3), binaryTree, pw); tree4b = tree4; tree4 = debinarizer.transformTree(tree4); if (op.nodePrune) { NodePruner np = new NodePruner(parser, debinarizer); tree4 = np.prune(tree4); } // tree4.pennPrint(); comboPE.evaluate(tc.transformTree(tree4), tc.transformTree(tree), pw); } // pcfgTE.evaluate(tree2, tree); pcfgTE.evaluate(tcEvalb.transformTree(tree2), tcEvalb.transformTree(tree), pw); pcfgTEnoPunct.evaluate(tc.transformTree(tree2), tc.transformTree(tree), pw); if (op.doDep) { comboTE.evaluate(tcEvalb.transformTree(tree4), tcEvalb.transformTree(tree), pw); comboTEnoPunct.evaluate(tc.transformTree(tree4), tc.transformTree(tree), pw); } System.out.println("PCFG only: " + parser.scoreBinarizedTree(tree2b, 0)); // tc.transformTree(tree2).pennPrint(); tree2.pennPrint(pw); if (op.doDep) { System.out.println("Combo: " + parser.scoreBinarizedTree(tree4b, 0)); // tc.transformTree(tree4).pennPrint(pw); tree4.pennPrint(pw); } System.out.println("Correct:" + parser.scoreBinarizedTree(binaryTree, 0)); /* if (parser.scoreBinarizedTree(tree2b,true) < parser.scoreBinarizedTree(binaryTree,true)) { System.out.println("SCORE INVERSION"); parser.validateBinarizedTree(binaryTree,0); } */ tree.pennPrint(pw); } // end if doPCFG if (Test.evalb) { if (op.doPCFG && op.doDep) { EvalB.writeEVALBline(tcEvalb.transformTree(tree), tcEvalb.transformTree(tree4)); } else if (op.doPCFG) { EvalB.writeEVALBline(tcEvalb.transformTree(tree), tcEvalb.transformTree(tree2)); } else if (op.doDep) { EvalB.writeEVALBline(tcEvalb.transformTree(tree), tcEvalb.transformTree(tree3db)); } } } // end for each tree in test treebank if (Test.evalb) { EvalB.closeEVALBfiles(); } // Test.display(); if (op.doPCFG) { pcfgPE.display(false, pw); System.out.println("Grammar size: " + Numberer.getGlobalNumberer("states").total()); pcfgCB.display(false, pw); if (op.doDep) { comboPE.display(false, pw); } pcfgTE.display(false, pw); pcfgTEnoPunct.display(false, pw); if (op.doDep) { comboTE.display(false, pw); comboTEnoPunct.display(false, pw); } } if (op.doDep) { depTE.display(false, pw); depDE.display(false, pw); } if (op.doPCFG && op.doDep) { comboDE.display(false, pw); } // pcfgPE.printGoodBad(); }
public void init() { Arrays.fill(inStatePrev, false); Arrays.fill(inStateNext, false); inStatePrev[initialState] = true; }
/** * Do max language model markov segmentation. Note that this algorithm inherently tags words as it * goes, but that we throw away the tags in the final result so that the segmented words are * untagged. (Note: for a couple of years till Aug 2007, a tagged result was returned, but this * messed up the parser, because it could use no tagging but the given tagging, which often wasn't * very good. Or in particular it was a subcategorized tagging which never worked with the current * forceTags option which assumes that gold taggings are inherently basic taggings.) * * @param s A String to segment * @return The list of segmented words. */ private ArrayList<HasWord> segmentWordsWithMarkov(String s) { int length = s.length(); // Set<String> POSes = (Set<String>) POSDistribution.keySet(); // 1.5 int numTags = POSes.size(); // score of span with initial word of this tag double[][][] scores = new double[length][length + 1][numTags]; // best (length of) first word for this span with this tag int[][][] splitBacktrace = new int[length][length + 1][numTags]; // best tag for second word over this span, if first is this tag int[][][] POSbacktrace = new int[length][length + 1][numTags]; for (int i = 0; i < length; i++) { for (int j = 0; j < length + 1; j++) { Arrays.fill(scores[i][j], Double.NEGATIVE_INFINITY); } } // first fill in word probabilities for (int diff = 1; diff <= 10; diff++) { for (int start = 0; start + diff <= length; start++) { int end = start + diff; StringBuilder wordBuf = new StringBuilder(); for (int pos = start; pos < end; pos++) { wordBuf.append(s.charAt(pos)); } String word = wordBuf.toString(); for (String tag : POSes) { IntTaggedWord itw = new IntTaggedWord(word, tag, wordIndex, tagIndex); double score = lex.score(itw, 0, word, null); if (start == 0) { score += Math.log(initialPOSDist.probabilityOf(tag)); } scores[start][end][itw.tag()] = score; splitBacktrace[start][end][itw.tag()] = end; } } } // now fill in word combination probabilities for (int diff = 2; diff <= length; diff++) { for (int start = 0; start + diff <= length; start++) { int end = start + diff; for (int split = start + 1; split < end && split - start <= 10; split++) { for (String tag : POSes) { int tagNum = tagIndex.indexOf(tag, true); if (splitBacktrace[start][split][tagNum] != split) { continue; } Distribution<String> rTagDist = markovPOSDists.get(tag); if (rTagDist == null) { continue; // this happens with "*" POS } for (String rTag : POSes) { int rTagNum = tagIndex.indexOf(rTag, true); double newScore = scores[start][split][tagNum] + scores[split][end][rTagNum] + Math.log(rTagDist.probabilityOf(rTag)); if (newScore > scores[start][end][tagNum]) { scores[start][end][tagNum] = newScore; splitBacktrace[start][end][tagNum] = split; POSbacktrace[start][end][tagNum] = rTagNum; } } } } } } int nextPOS = ArrayMath.argmax(scores[0][length]); ArrayList<HasWord> words = new ArrayList<HasWord>(); int start = 0; while (start < length) { int split = splitBacktrace[start][length][nextPOS]; StringBuilder wordBuf = new StringBuilder(); for (int i = start; i < split; i++) { wordBuf.append(s.charAt(i)); } String word = wordBuf.toString(); // String tag = tagIndex.get(nextPOS); // words.add(new TaggedWord(word, tag)); words.add(new Word(word)); if (split < length) { nextPOS = POSbacktrace[start][length][nextPOS]; } start = split; } return words; }
// CDM 2007: I wonder what this does differently from segmentWordsWithMarkov??? private ArrayList<TaggedWord> basicSegmentWords(String s) { int length = s.length(); // Set<String> POSes = (Set<String>) POSDistribution.keySet(); // 1.5 // best score of span double[][] scores = new double[length][length + 1]; // best (last index of) first word for this span int[][] splitBacktrace = new int[length][length + 1]; // best tag for word over this span int[][] POSbacktrace = new int[length][length + 1]; for (int i = 0; i < length; i++) { Arrays.fill(scores[i], Double.NEGATIVE_INFINITY); } // first fill in word probabilities for (int diff = 1; diff <= 10; diff++) { for (int start = 0; start + diff <= length; start++) { int end = start + diff; StringBuilder wordBuf = new StringBuilder(); for (int pos = start; pos < end; pos++) { wordBuf.append(s.charAt(pos)); } String word = wordBuf.toString(); // for (String tag : POSes) { // 1.5 for (Iterator<String> iter = POSes.iterator(); iter.hasNext(); ) { String tag = iter.next(); IntTaggedWord itw = new IntTaggedWord(word, tag, wordIndex, tagIndex); double newScore = lex.score(itw, 0, word, null) + Math.log(lex.getPOSDistribution().probabilityOf(tag)); if (newScore > scores[start][end]) { scores[start][end] = newScore; splitBacktrace[start][end] = end; POSbacktrace[start][end] = itw.tag(); } } } } // now fill in word combination probabilities for (int diff = 2; diff <= length; diff++) { for (int start = 0; start + diff <= length; start++) { int end = start + diff; for (int split = start + 1; split < end && split - start <= 10; split++) { if (splitBacktrace[start][split] != split) { continue; // only consider words on left } double newScore = scores[start][split] + scores[split][end]; if (newScore > scores[start][end]) { scores[start][end] = newScore; splitBacktrace[start][end] = split; } } } } List<TaggedWord> words = new ArrayList<TaggedWord>(); int start = 0; while (start < length) { int end = splitBacktrace[start][length]; StringBuilder wordBuf = new StringBuilder(); for (int pos = start; pos < end; pos++) { wordBuf.append(s.charAt(pos)); } String word = wordBuf.toString(); String tag = tagIndex.get(POSbacktrace[start][end]); words.add(new TaggedWord(word, tag)); start = end; } return new ArrayList<TaggedWord>(words); }