/*
* This file is part of ELKI:
* Environment for Developing KDD-Applications Supported by Index-Structures
*
* Copyright (C) 2017
* ELKI Development Team
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package de.lmu.ifi.dbs.elki.evaluation.outlier;
import java.util.List;
import java.util.regex.Pattern;
import de.lmu.ifi.dbs.elki.database.Database;
import de.lmu.ifi.dbs.elki.database.DatabaseUtil;
import de.lmu.ifi.dbs.elki.database.ids.DBIDIter;
import de.lmu.ifi.dbs.elki.database.ids.DBIDUtil;
import de.lmu.ifi.dbs.elki.database.ids.DBIDs;
import de.lmu.ifi.dbs.elki.database.ids.SetDBIDs;
import de.lmu.ifi.dbs.elki.evaluation.Evaluator;
import de.lmu.ifi.dbs.elki.logging.Logging;
import de.lmu.ifi.dbs.elki.math.geometry.XYCurve;
import de.lmu.ifi.dbs.elki.result.OrderingResult;
import de.lmu.ifi.dbs.elki.result.Result;
import de.lmu.ifi.dbs.elki.result.ResultHierarchy;
import de.lmu.ifi.dbs.elki.result.ResultUtil;
import de.lmu.ifi.dbs.elki.result.outlier.OutlierResult;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.AbstractParameterizer;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.OptionID;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameterization.Parameterization;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.IntParameter;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.PatternParameter;
/**
* Compute a curve containing the precision values for an outlier detection
* method.
*
* @author Erich Schubert
* @since 0.5.0
*
* @apiviz.has PrecisionAtKCurve
*/
public class OutlierPrecisionAtKCurve implements Evaluator {
/**
* The logger.
*/
private static final Logging LOG = Logging.getLogger(OutlierPrecisionAtKCurve.class);
/**
* Stores the "positive" class.
*/
private Pattern positiveClassName;
/**
* Maximum value for k
*/
private int maxk = Integer.MAX_VALUE;
/**
* Constructor.
*
* @param positiveClassName Pattern to recognize outliers
* @param maxk Maximum value for k
*/
public OutlierPrecisionAtKCurve(Pattern positiveClassName, int maxk) {
super();
this.positiveClassName = positiveClassName;
this.maxk = maxk;
}
@Override
public void processNewResult(ResultHierarchy hier, Result result) {
Database db = ResultUtil.findDatabase(hier);
// Prepare
SetDBIDs positiveids = DBIDUtil.ensureSet(DatabaseUtil.getObjectsByLabelMatch(db, positiveClassName));
if(positiveids.size() == 0) {
LOG.warning("Computing a ROC curve failed - no objects matched.");
return;
}
List<OutlierResult> oresults = OutlierResult.getOutlierResults(result);
List<OrderingResult> orderings = ResultUtil.getOrderingResults(result);
// Outlier results are the main use case.
for(OutlierResult o : oresults) {
DBIDs sorted = o.getOrdering().order(o.getOrdering().getDBIDs());
db.getHierarchy().add(o, computePrecisionResult(o.getScores().size(), positiveids, sorted));
// Process them only once.
orderings.remove(o.getOrdering());
}
// FIXME: find appropriate place to add the derived result
// otherwise apply an ordering to the database IDs.
for(OrderingResult or : orderings) {
DBIDs sorted = or.order(or.getDBIDs());
db.getHierarchy().add(or, computePrecisionResult(or.getDBIDs().size(), positiveids, sorted));
}
}
private XYCurve computePrecisionResult(int size, SetDBIDs positiveids, DBIDs order) {
if(order.size() != size) {
throw new IllegalStateException("Iterable result doesn't match database size - incomplete ordering?");
}
int lastk = Math.min(size, maxk);
XYCurve curve = new PrecisionAtKCurve("k", "Precision", lastk);
int pos = 0;
DBIDIter i = order.iter();
for(int k = 1; k <= lastk; k++, i.advance()) {
if(positiveids.contains(i)) {
pos++;
}
curve.addAndSimplify(k, pos / (double) k);
}
return curve;
}
/**
* Precision at K curve.
*
* @author Erich Schubert
*/
public static class PrecisionAtKCurve extends XYCurve {
/**
* Constructor.
*
* @param size Size estimation
*/
public PrecisionAtKCurve(String labelx, String labely, int size) {
super("k", "Precision", size);
}
@Override
public String getLongName() {
return "Precision @ k Curve";
}
@Override
public String getShortName() {
return "precision-at-k";
}
}
/**
* Parameterization class.
*
* @author Erich Schubert
*
* @apiviz.exclude
*/
public static class Parameterizer extends AbstractParameterizer {
/**
* The pattern to identify positive classes.
*
* <p>
* Key: {@code -precision.positive}
* </p>
*/
public static final OptionID POSITIVE_CLASS_NAME_ID = new OptionID("precision.positive", "Class label for the 'positive' class.");
/**
* Maximum value for k
*
* <p>
* Key: {@code -precision.k}
* </p>
*/
public static final OptionID MAX_K_ID = new OptionID("precision.maxk", "Maximum value of 'k' to compute the curve up to.");
/**
* Stores the "positive" class.
*/
private Pattern positiveClassName;
/**
* Maximum value for k
*/
private int maxk = Integer.MAX_VALUE;
@Override
protected void makeOptions(Parameterization config) {
super.makeOptions(config);
PatternParameter positiveClassNameP = new PatternParameter(POSITIVE_CLASS_NAME_ID);
if(config.grab(positiveClassNameP)) {
positiveClassName = positiveClassNameP.getValue();
}
IntParameter maxkP = new IntParameter(MAX_K_ID);
maxkP.setOptional(true);
if(config.grab(maxkP)) {
maxk = maxkP.getValue();
}
}
@Override
protected OutlierPrecisionAtKCurve makeInstance() {
return new OutlierPrecisionAtKCurve(positiveClassName, maxk);
}
}
}