/*
* This file is part of JGAP.
*
* JGAP offers a dual license model containing the LGPL as well as the MPL.
*
* For licensing information please see the file license.txt included with JGAP
* or have a look at the top of class org.jgap.Chromosome which representatively
* includes the JGAP license policy applicable for any file delivered with JGAP.
*/
package org.jgap.gp.function.statistics;
import org.apache.commons.math.stat.descriptive.*;
import org.jgap.*;
import org.jgap.gp.*;
import org.jgap.gp.impl.*;
import org.jgap.util.*;
/**
* Computes the Kurtosis of the available values.
* <p>
* We use the following (unbiased) formula to define kurtosis:</p>
* <p>
* kurtosis = { [n(n+1) / (n -1)(n - 2)(n-3)] sum[(x_i - mean)^4] / std^4 } - [3(n-1)^2 / (n-2)(n-3)]
* </p><p>
* where n is the number of values, and std is the
* Standard Deviation</p>
*
* @author Luis Garcia
* @since 3.5
*/
public class Kurtosis
extends CommandDynamicArity implements ICloneable {
public Kurtosis(GPConfiguration a_conf, int a_arityInitial, int a_arityMin,
int a_arityMax, Class a_returnType)
throws InvalidConfigurationException {
super(a_conf, a_arityInitial, a_arityMin, a_arityMax, a_returnType);
}
@Override
public String toString() {
String s = "Kurtosis(";
int size = size();
for (int i = 0; i < size; i++) {
if (i > 0) {
s += ";";
}
s += "&" + (i + 1);
}
return s + ")";
}
@Override
public double execute_double(ProgramChromosome c, int n, Object[] args) {
int size = size();
DescriptiveStatistics stats = new DescriptiveStatistics();
for (int i = 0; i < size; i++) {
stats.addValue(c.execute_double(n, i, args));
}
return stats.getKurtosis();
}
@Override
public float execute_float(ProgramChromosome c, int n, Object[] args) {
int size = size();
DescriptiveStatistics stats = new DescriptiveStatistics();
for (int i = 0; i < size; i++) {
stats.addValue(c.execute_float(n, i, args));
}
return (float) stats.getKurtosis();
}
@Override
public String getName() {
return "Kurtosis";
}
@Override
public Object clone() {
try {
Kurtosis result = new Kurtosis(getGPConfiguration(), getArity(null),
getArityMin(), getArityMax(),
getReturnType());
return result;
} catch (Exception ex) {
throw new CloneException(ex);
}
}
}