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package de.lmu.ifi.dbs.elki.utilities.scaling;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2015
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.math.DoubleMinMax;
/**
* Simple linear scaling function.
*
* @author Erich Schubert
*/
public class LinearScaling implements StaticScalingFunction {
/**
* Scaling factor
*/
private double factor;
/**
* Shift
*/
private double shift;
/**
* Constructor with defaults resulting in identity.
*/
public LinearScaling() {
this(1.0, 0.0);
}
/**
* Constructor with scaling only.
*
* @param factor Scaling factor
*/
public LinearScaling(double factor) {
this(factor, 0.0);
}
/**
* Full constructor.
*
* @param factor Scaling factor
* @param shift Shift value
*/
public LinearScaling(double factor, double shift) {
this.factor = factor;
this.shift = shift;
}
/**
* Constructor from a double minmax.
*
* @param minmax Minimum and Maximum
*/
public LinearScaling(DoubleMinMax minmax) {
this.factor = 1.0 / (minmax.getMax() - minmax.getMin());
this.shift = -minmax.getMin() * this.factor;
}
@Override
public double getScaled(double d) {
return factor * d + shift;
}
@Override
public double getMin() {
return Double.NEGATIVE_INFINITY;
}
@Override
public double getMax() {
return Double.POSITIVE_INFINITY;
}
/**
* Make a linear scaling from a given minimum and maximum. The minimum will be
* mapped to zero, the maximum to one.
*
* @param min Minimum
* @param max Maximum
* @return New linear scaling.
*/
public static LinearScaling fromMinMax(double min, double max) {
double zoom = 1.0 / (max - min);
return new LinearScaling(zoom, -min * zoom);
}
}
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