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.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.DoubleParameter;
/**
* Scaling that can map arbitrary positive values to a value in the range of
* [0:1].
*
* Transformation is done by taking the square root, then doing a linear linear
* mapping onto 0:1 using the minimum values seen.
*
* @author Erich Schubert
*/
public class OutlierSqrtScaling implements OutlierScalingFunction {
/**
* Parameter to specify the fixed minimum to use.
* <p>
* Key: {@code -sqrtscale.min}
* </p>
*/
public static final OptionID MIN_ID = OptionID.getOrCreateOptionID("sqrtscale.min", "Fixed minimum to use in sqrt scaling.");
/**
* Parameter to specify the fixed maximum to use.
* <p>
* Key: {@code -sqrtscale.max}
* </p>
*/
public static final OptionID MAX_ID = OptionID.getOrCreateOptionID("sqrtscale.max", "Fixed maximum to use in sqrt scaling.");
/**
* Field storing the minimum value
*/
protected Double min = null;
/**
* Field storing the Maximum value
*/
protected Double max = null;
/**
* Scaling factor
*/
protected double factor;
/**
* Constructor.
*
* @param min
* @param max
*/
public OutlierSqrtScaling(Double min, Double max) {
super();
this.min = min;
this.max = max;
}
@Override
public double getScaled(double value) {
assert (factor != 0) : "prepare() was not run prior to using the scaling function.";
if(value <= min) {
return 0;
}
return Math.min(1, (Math.sqrt(value - min) / factor));
}
@Override
public void prepare(OutlierResult or) {
if(min == null || max == null) {
DoubleMinMax mm = new DoubleMinMax();
for(DBID id : or.getScores().iterDBIDs()) {
double val = or.getScores().get(id);
if(!Double.isNaN(val) && !Double.isInfinite(val)) {
mm.put(val);
}
}
if(min == null) {
min = mm.getMin();
}
if(max == null) {
max = mm.getMax();
}
}
factor = Math.sqrt(max - min);
}
@Override
public double getMin() {
return 0.0;
}
@Override
public double getMax() {
return 1.0;
}
/**
* Parameterization class.
*
* @author Erich Schubert
*
* @apiviz.exclude
*/
public static class Parameterizer extends AbstractParameterizer {
protected double min;
protected double max;
@Override
protected void makeOptions(Parameterization config) {
super.makeOptions(config);
DoubleParameter minP = new DoubleParameter(MIN_ID, true);
if(config.grab(minP)) {
min = minP.getValue();
}
DoubleParameter maxP = new DoubleParameter(MAX_ID, true);
if(config.grab(maxP)) {
max = maxP.getValue();
}
}
@Override
protected OutlierSqrtScaling makeInstance() {
return new OutlierSqrtScaling(min, max);
}
}
}