public LinearClassifier createLinearClassifier(double[] weights) {
double[][] weights2D;
if (objective != null) {
weights2D = objective.to2D(weights);
} else {
weights2D = ArrayUtils.to2D(weights, featureIndex.size(), labelIndex.size());
}
return new LinearClassifier<L, F>(weights2D, featureIndex, labelIndex);
}
public Double apply(Double sigmaToTry) {
double[][] weights2D;
setSigma(sigmaToTry);
weights2D = trainWeights(trainSet, weights, true); // bypass.
weights = ArrayUtils.flatten(weights2D);
LinearClassifier<L, F> classifier =
new LinearClassifier<L, F>(weights2D, trainSet.featureIndex, trainSet.labelIndex);
double score = scorer.score(classifier, devSet);
// System.out.println("score: "+score);
// System.out.print(".");
System.err.print("##sigma = " + getSigma() + " ");
System.err.println("-> average Score: " + score);
System.err.println("##time elapsed: " + timer.stop() + " milliseconds.");
timer.restart();
return -score;
}
/**
* Sets the sigma parameter to a value that optimizes the held-out score given by <code>scorer
* </code>. Search for an optimal value is carried out by <code>minimizer</code> dataset the data
* set to optimize sigma on. kfold
*
* @return an interim set of optimal weights: the weights
*/
public double[] heldOutSetSigma(
final GeneralDataset<L, F> trainSet,
final GeneralDataset<L, F> devSet,
final Scorer<L> scorer,
LineSearcher minimizer) {
featureIndex = trainSet.featureIndex;
labelIndex = trainSet.labelIndex;
// double[] resultWeights = null;
Timing timer = new Timing();
NegativeScorer negativeScorer = new NegativeScorer(trainSet, devSet, scorer, timer);
timer.start();
double bestSigma = minimizer.minimize(negativeScorer);
System.err.println("##best sigma: " + bestSigma);
setSigma(bestSigma);
return ArrayUtils.flatten(
trainWeights(
trainSet,
negativeScorer.weights,
true)); // make sure it's actually the interim weights from best sigma
}
public LinearClassifier<L, F> trainClassifierWithInitialWeights(
GeneralDataset<L, F> dataset, double[][] initialWeights2D) {
double[] initialWeights =
(initialWeights2D != null) ? ArrayUtils.flatten(initialWeights2D) : null;
return trainClassifier(dataset, initialWeights);
}