com.expleague.ml.models.multiclass.MulticlassCodingMatrixModel Maven / Gradle / Ivy
package com.expleague.ml.models.multiclass;
import com.expleague.commons.math.MathTools;
import com.expleague.commons.math.metrics.Metric;
import com.expleague.commons.math.vectors.Mx;
import com.expleague.commons.math.vectors.Vec;
import com.expleague.commons.math.vectors.VecIterator;
import com.expleague.commons.math.vectors.VecTools;
import com.expleague.commons.math.vectors.impl.vectors.ArrayVec;
import com.expleague.commons.util.logging.Logger;
import com.expleague.commons.util.ArrayTools;
import com.expleague.commons.math.Func;
import com.expleague.ml.func.FuncJoin;
import static java.lang.Math.exp;
import static java.lang.Math.log;
/**
* User: qdeee
* Date: 04.06.14
* Time: 10:59
*/
public class MulticlassCodingMatrixModel extends MCModel.Stub {
public static final Logger LOG = Logger.create(MulticlassCodingMatrixModel.class);
protected final FuncJoin binaryClassifiers;
protected final Mx codingMatrix;
protected final double ignoreThreshold;
protected final Metric metric;
public MulticlassCodingMatrixModel(final Mx codingMatrix, final Func[] binaryClassifiers, final double ignoreTreshold) {
LOG.assertTrue(codingMatrix.columns() == binaryClassifiers.length, "Coding matrix columns count must match binary classifiers.");
this.binaryClassifiers = new FuncJoin(binaryClassifiers);
this.codingMatrix = codingMatrix;
this.ignoreThreshold = ignoreTreshold;
this.metric = new LossBasedSkipZeroMetric();
}
public FuncJoin getInternalModel() {
return binaryClassifiers;
}
private Vec binarize(final Vec trans) {
final Vec copy = VecTools.copy(trans);
for (final VecIterator it = copy.nonZeroes(); it.advance(); ) {
if (Math.abs(it.value()) > ignoreThreshold)
it.setValue(Math.signum(it.value()));
else
it.setValue(0.0);
}
return copy;
}
protected double[] calcDistances(final Vec trans) {
final double[] dist = new double[codingMatrix.rows()];
final Vec binarize = binarize(trans);
for (int i = 0; i < dist.length; i++) {
dist[i] = metric.distance(binarize, codingMatrix.row(i));
}
return dist;
}
@Override
public int countClasses() {
return codingMatrix.rows();
}
@Override
public Vec probs(final Vec x) {
final Vec trans = binaryClassifiers.trans(x);
final double[] dist = calcDistances(trans);
for (int i = 0; i < dist.length; i++) {
dist[i] = 1 - dist[i];
}
return new ArrayVec(dist);
}
@Override
public int bestClass(final Vec x) {
final Vec trans = binaryClassifiers.trans(x);
final double[] dist = calcDistances(trans);
return ArrayTools.min(dist);
}
@Override
public int dim() {
return binaryClassifiers.xdim();
}
protected static class LossBasedSkipZeroMetric implements Metric {
@Override
public double distance(final Vec trans, final Vec row) {
double result = 0;
for (int l = 0; l < trans.dim(); l++) {
final double prob = MathTools.sigmoid(trans.get(l));
final double code = row.get(l);
if (code > 0)
result += log(prob);
else if (code < 0)
result += log(1 - prob);
}
return 1 - exp(result / trans.dim());
}
}
public Mx getCodingMatrix() {
return codingMatrix;
}
}
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