package de.lmu.ifi.dbs.elki.utilities.scaling.outlier;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2012
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
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/>.
*/
import de.lmu.ifi.dbs.elki.database.ids.DBID;
import de.lmu.ifi.dbs.elki.math.DoubleMinMax;
import de.lmu.ifi.dbs.elki.math.MeanVariance;
import de.lmu.ifi.dbs.elki.result.outlier.OutlierResult;
import de.lmu.ifi.dbs.elki.utilities.documentation.Reference;
/**
* Normalization used by HeDES
*
* @author Erich Schubert
*/
@Reference(authors = "H. V. Nguyen, H. H. Ang, V. Gopalkrishnan", title = "Mining Outliers with Ensemble of Heterogeneous Detectors on Random Subspaces", booktitle = "Proc. 15th International Conference on Database Systems for Advanced Applications (DASFAA 2010)", url = "http://dx.doi.org/10.1007/978-3-642-12026-8_29")
public class HeDESNormalizationOutlierScaling implements OutlierScalingFunction {
/**
* Mean
*/
double mean;
/**
* Standard deviation
*/
double stddev;
/**
* Minimum after scaling
*/
double scaledmin;
/**
* Maximum after scaling
*/
double scaledmax;
@Override
public void prepare(OutlierResult or) {
MeanVariance mv = new MeanVariance();
DoubleMinMax minmax = new DoubleMinMax();
for(DBID id : or.getScores().iterDBIDs()) {
double val = or.getScores().get(id);
if(!Double.isNaN(val) && !Double.isInfinite(val)) {
mv.put(val);
minmax.put(val);
}
}
mean = mv.getMean();
stddev = mv.getSampleStddev();
scaledmax = getScaled(minmax.getMax());
scaledmin = getScaled(minmax.getMin());
}
@Override
public double getMax() {
return scaledmax;
}
@Override
public double getMin() {
return scaledmin;
}
@Override
public double getScaled(double value) {
assert (stddev > 0 || (value == mean)) : "prepare() was not run prior to using the scaling function.";
return (value - mean) / stddev;
}
}