/**
* Copyright (C) 2001-2017 by RapidMiner and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapidminer.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.tools.math.som;
/**
* This class provides a distance measure, equivalent to the euclidian distance measure.
*
* @author Sebastian Land
*/
public class EuclideanDistance implements DistanceFunction {
private static final long serialVersionUID = 1127224325142026906L;
@Override
public double getDistance(double[] point1, double[] point2) {
double distance = 0;
for (int i = 0; i < point1.length; i++) {
double current = point1[i] - point2[i];
distance += current * current;
}
distance = Math.sqrt(distance);
if (!Double.isNaN(distance)) {
return distance;
} else {
distance = 0;
for (int i = 0; i < point1.length; i++) {
double currentDistance = (point1[i] - point2[i]);
if (!Double.isNaN(currentDistance)) {
distance += currentDistance * currentDistance;
}
}
return Math.sqrt(distance);
}
}
@Override
public double getDistance(int[] point1, int[] point2) {
double distance = 0;
for (int i = 0; i < point1.length; i++) {
double diff = point1[i] - point2[i];
distance += diff * diff;
}
distance = Math.sqrt(distance);
return distance;
}
/** Integer distance calculation regards the wrap around of the net (hypertorus) */
@Override
public double getDistance(int[] point1, int[] point2, int[] dimensions) {
double distance = 0;
for (int i = 0; i < point1.length; i++) {
int coord1 = (point1[i] < 0) ? dimensions[i] + point1[i] : point1[i]; // wrapping around
// if incoming
// coordinate is
// negative
int coord2 = (point2[i] < 0) ? dimensions[i] + point2[i] : point2[i];
double diff = Math.min(Math.abs(coord1 - coord2), (coord1 + dimensions[i] - coord2) % dimensions[i]);
distance += diff * diff;
}
distance = Math.sqrt(distance);
return distance;
}
}