@Override
public void initialize(Parameters params) throws ResourceInitializationException {
super.initialize(params);
if (params.contains(Constants.REPRESENTER)) {
representer = (TextRepresenter) params.get(Constants.REPRESENTER);
} else {
throw new ResourceInitializationException("No text representer specified.");
}
if (params.contains(Constants.FIND_BEST_PARAMETERS)) {
findBestParameters = params.getBoolean(Constants.FIND_BEST_PARAMETERS);
} else {
gamma = 1.0 / (double) representer.getFeatures().size();
}
if (params.contains(Constants.C)) {
if (findBestParameters) {
logger.warn("Finding best parameters. The specified C value will be ignored.");
} else {
c = params.getDouble(Constants.C);
}
}
if (params.contains(Constants.WEIGHTS)) {
// Parse weight specs
weights = new TreeMap<Integer, Double>();
for (String piece : params.getString(Constants.WEIGHTS).split(",\\s*")) {
String[] pair = piece.split(":");
if (pair.length != 2) {
throw new ResourceInitializationException(
"Invalid weight specs in " + params.getString(Constants.WEIGHTS));
}
try {
int i = Integer.parseInt(pair[0]);
double w = Double.parseDouble(pair[1]);
weights.put(i, w);
} catch (Exception e) {
throw new ResourceInitializationException(
"Invalid weight specs in " + params.getString(Constants.WEIGHTS), e);
}
}
}
if (params.contains(Constants.GAMMA)) {
if (findBestParameters) {
logger.warn("Finding best parameters. The specified gamma value will be ignored.");
} else {
gamma = params.getDouble(Constants.GAMMA);
}
}
if (params.contains(Constants.SAMPLE)) {
if (findBestParameters) {
sample = params.getDouble(Constants.SAMPLE);
if (sample <= 0 || sample > 1) {
throw new ResourceInitializationException("Invalid sample value " + sample);
}
} else {
logger.warn(
"Sample value valid for parameter optimization only. Provided sample value will be ignored.");
}
}
if (params.contains(Constants.NUMBER_OF_THREADS)) {
numberOfThreads = params.getInt(Constants.NUMBER_OF_THREADS);
if (numberOfThreads < 1) {
throw new ResourceInitializationException(Constants.NUMBER_OF_THREADS + " must be >= 1");
}
}
if (params.contains(Constants.TARGET_CLASS)) {
targetClass = params.getString(Constants.TARGET_CLASS);
logger.debug("Target Class: " + targetClass);
}
}
public svm_problem loadData(CollectionReader cr) {
logger.debug("Loading " + cr.getSize() + " documents.");
List<svm_node[]> data = new LinkedList<svm_node[]>();
List<Set<String>> labels = new LinkedList<Set<String>>();
Set<String> allLabels = new HashSet<String>();
for (Analyzable a : cr) {
CategorizedTextContent ctc = (CategorizedTextContent) a;
Set<String> categories;
if (targetClass == null) {
categories = ctc.getCategories();
} else {
categories = new HashSet<String>();
if (ctc.getCategories().contains(targetClass)) {
// Not adding any other categories if item belongs to targetClass as well as some other
// category.
categories.add(targetClass);
} else {
categories.add("other");
}
}
labels.add(categories);
allLabels.addAll(categories);
data.add(representer.represent(ctc.getText()).toSvmNodes());
}
representer.shutdown();
labelList = new ArrayList<String>(allLabels);
Collections.sort(labelList);
logger.debug("Total labels: " + labelList.size());
logger.trace("Labels: " + labelList);
int numberOfExpandedData = 0;
for (Set<String> ls : labels) {
numberOfExpandedData += ls.size();
}
// Scale data
logger.debug("Scaling data.");
scaler = new ValueScaler(0, 1, data.toArray(new svm_node[0][]));
svm_node[][] scaledData = scaler.getScaledData();
// For every label, generate a copy of the data item.
logger.debug("Generating " + numberOfExpandedData + " records.");
svm_node[][] expandedData = new svm_node[numberOfExpandedData][];
double[] expandedLabels = new double[numberOfExpandedData];
int i = 0;
int xi = 0;
for (svm_node[] dataItem : scaledData) {
Set<String> trueLabels = labels.get(i++);
for (String label : trueLabels) {
double labelIndex = labelList.indexOf(label);
expandedData[xi] = dataItem.clone();
expandedLabels[xi++] = labelIndex;
}
}
svm_problem svmProblem = new svm_problem();
svmProblem.l = numberOfExpandedData;
svmProblem.x = expandedData;
svmProblem.y = expandedLabels;
return svmProblem;
}
