package com.digitalpebble.classification.liblinear;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import com.digitalpebble.classification.Document;
import com.digitalpebble.classification.Parameters;
import com.digitalpebble.classification.TextClassifier;
import com.digitalpebble.classification.Vector;
import de.bwaldvogel.liblinear.FeatureNode;
import de.bwaldvogel.liblinear.Linear;
import de.bwaldvogel.liblinear.Model;
public class LibLinearClassifier extends TextClassifier {
Model liblinearModel;
private static boolean flag_predict_probability = false;
public double[] classify(Document document) throws Exception {
int nr_class = liblinearModel.getNrClass();
double[] prob_estimates = new double[nr_class];
int n;
int nr_feature = liblinearModel.getNrFeature();
if (liblinearModel.getBias() >= 0) n = nr_feature + 1;
else n = nr_feature;
int[] labels = liblinearModel.getLabels();
// convert docs into liblinear format
List<FeatureNode> x = new ArrayList<FeatureNode>();
Vector vector = document.getFeatureVector(this.lexicon);
int[] indices = vector.getIndices();
double[] values = vector.getValues();
for (int indexpos = 0; indexpos < indices.length; indexpos++) {
int index = indices[indexpos];
if (index <= nr_feature) {
FeatureNode node = new FeatureNode(index, values[indexpos]);
x.add(node);
}
}
if (liblinearModel.getBias() >= 0) {
FeatureNode node = new FeatureNode(n, liblinearModel.getBias());
x.add(node);
}
FeatureNode[] nodes = new FeatureNode[x.size()];
nodes = x.toArray(nodes);
if (flag_predict_probability) {
Linear.predictProbability(liblinearModel, nodes, prob_estimates);
return prob_estimates;
}
int predict_label = Linear.predict(liblinearModel, nodes);
if (prob_estimates.length <= predict_label) prob_estimates = new double[prob_estimates.length + 1];
prob_estimates[predict_label] = 1d;
return prob_estimates;
}
protected void loadModel() throws Exception {
String modelPath = pathResourceDirectory + java.io.File.separator
+ Parameters.modelName;
liblinearModel = Model.load(new File(modelPath));
}
}