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package de.lmu.ifi.dbs.elki.math.statistics.distribution;
/*
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 java.util.Random;
import de.lmu.ifi.dbs.elki.math.random.RandomFactory;
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;
/**
* Uniform distribution.
*
* @author Erich Schubert
*/
public class UniformDistribution extends AbstractDistribution {
/**
* Minimum
*/
private double min;
/**
* Maximum
*/
private double max;
/**
* Len := max - min
*/
private double len;
/**
* Constructor for a uniform distribution on the interval [min, max[
*
* @param min Minimum value
* @param max Maximum value
* @param random Random generator
*/
public UniformDistribution(double min, double max, RandomFactory random) {
super(random);
if (Double.isInfinite(min) || Double.isInfinite(max)) {
throw new ArithmeticException("Infinite values given for uniform distribution.");
}
if (Double.isNaN(min) || Double.isNaN(max)) {
throw new ArithmeticException("NaN values given for uniform distribution.");
}
// Swap parameters if they were given incorrectly.
if (min > max) {
double tmp = min;
min = max;
max = tmp;
}
this.min = min;
this.max = max;
this.len = max - min;
}
/**
* Constructor for a uniform distribution on the interval [min, max[
*
* @param min Minimum value
* @param max Maximum value
* @param random Random generator
*/
public UniformDistribution(double min, double max, Random random) {
super(random);
if (Double.isInfinite(min) || Double.isInfinite(max)) {
throw new ArithmeticException("Infinite values given for uniform distribution.");
}
if (Double.isNaN(min) || Double.isNaN(max)) {
throw new ArithmeticException("NaN values given for uniform distribution.");
}
// Swap parameters if they were given incorrectly.
if (min > max) {
double tmp = min;
min = max;
max = tmp;
}
this.min = min;
this.max = max;
this.len = max - min;
}
/**
* Constructor for a uniform distribution on the interval [min, max[
*
* @param min Minimum value
* @param max Maximum value
*/
public UniformDistribution(double min, double max) {
this(min, max, (Random) null);
}
@Override
public double pdf(double val) {
if (!(val >= min) || val >= max) {
return 0.0;
}
return (len > 0.) ? 1.0 / len : Double.POSITIVE_INFINITY;
}
@Override
public double cdf(double val) {
if (!(val > min)) {
return 0.;
}
if (val >= max) {
return 1.;
}
return (len > 0.) ? (val - min) / len : .5;
}
@Override
public double quantile(double val) {
return min + len * val;
}
@Override
public double nextRandom() {
return min + random.nextDouble() * len;
}
@Override
public String toString() {
return "UniformDistribution(min=" + min + ", max=" + max + ")";
}
/**
* @return the minimum value
*/
public double getMin() {
return min;
}
/**
* @return the maximum value
*/
public double getMax() {
return max;
}
/**
* Parameterization class
*
* @author Erich Schubert
*
* @apiviz.exclude
*/
public static class Parameterizer extends AbstractDistribution.Parameterizer {
/**
* Minimum value
*/
public static final OptionID MIN_ID = new OptionID("distribution.min", "Minimum value of distribution.");
/**
* Maximum value
*/
public static final OptionID MAX_ID = new OptionID("distribution.max", "Maximum value of distribution.");
/** Parameters. */
double min, max;
@Override
protected void makeOptions(Parameterization config) {
super.makeOptions(config);
DoubleParameter minP = new DoubleParameter(MIN_ID);
if (config.grab(minP)) {
min = minP.doubleValue();
}
DoubleParameter maxP = new DoubleParameter(MAX_ID);
if (config.grab(maxP)) {
max = maxP.doubleValue();
}
}
@Override
protected UniformDistribution makeInstance() {
return new UniformDistribution(min, max, rnd);
}
}
}
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