/*
* RapidMiner
*
* Copyright (C) 2001-2011 by Rapid-I and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapid-i.com
*
* 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/.
*/
package com.rapidminer.operator.learner.functions.kernel.jmysvm.kernel;
/**
* Anova Kernel
*
* @author Ingo Mierswa
*/
public class KernelAnova extends Kernel {
private static final long serialVersionUID = -8670034220969832253L;
private double sigma = 1;
private double degree = 1;
/** Class constructor. */
public KernelAnova() {}
public void setParameters(double sigma, double degree) {
this.sigma = sigma;
this.degree = degree;
}
/** Calculates kernel value of vectors x and y. */
@Override
public double calculate_K(int[] x_index, double[] x_att, int[] y_index, double[] y_att) {
double result = 0;
double tmp;
int xpos = x_index.length - 1;
int ypos = y_index.length - 1;
int zeros = dim;
while ((xpos >= 0) && (ypos >= 0)) {
if (x_index[xpos] == y_index[ypos]) {
tmp = x_att[xpos] - y_att[ypos];
result += Math.exp(-sigma * tmp * tmp);
xpos--;
ypos--;
} else if (x_index[xpos] > y_index[ypos]) {
tmp = x_att[xpos];
result += Math.exp(-sigma * tmp * tmp);
xpos--;
} else {
tmp = y_att[ypos];
result += Math.exp(-sigma * tmp * tmp);
ypos--;
}
zeros--;
}
while (xpos >= 0) {
tmp = x_att[xpos];
result += Math.exp(-sigma * tmp * tmp);
xpos--;
zeros--;
}
while (ypos >= 0) {
tmp = y_att[ypos];
result += Math.exp(-sigma * tmp * tmp);
ypos--;
zeros--;
}
result += zeros;
return Math.pow(result, degree);
}
/** Output as String */
@Override
public String toString() {
return ("anova(s = " + sigma + ", d = " + degree + ")");
}
@Override
public String getDistanceFormula(double[] x, String[] attributeConstructions) {
StringBuffer result = new StringBuffer();
result.append("pow((");
boolean first = true;
for (int i = 0; i < x.length; i++) {
double value = x[i];
String valueString = "(" + value + " - " + attributeConstructions[i] + ")";
if (first) {
result.append("exp(-" + sigma + " * " + valueString + " * " + valueString + ")");
} else {
result.append(" + exp(-" + sigma + " * " + valueString + " * " + valueString + ")");
}
first = false;
}
result.append("), " + degree + ")");
return result.toString();
}
}