/*
* RapidMiner
*
* Copyright (C) 2001-2008 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.tools.math;
import java.util.LinkedList;
import java.util.List;
/**
* This simple implementation returns a peak if the specified number of
* neighbors is smaller than the current value.
*
* @author Ingo Mierswa
* @version $Id: SimplePeakFinder.java,v 1.3 2008/05/09 19:23:03 ingomierswa Exp $
*/
public class SimplePeakFinder implements PeakFinder {
private int numberOfNeighbours = 5;
public SimplePeakFinder(int neighbours) {
this.numberOfNeighbours = neighbours;
}
/** Returns a list with peaks. */
public List<Peak> getPeaks(Peak[] series) {
List<Peak> result = new LinkedList<Peak>();
for (int i = 0; i < series.length; i++) {
if (isPeak(series, i)) {
result.add(series[i]);
}
}
return result;
}
/**
* Returns true if the value for index is an extremum of the given type
* between the given numbers of neighbours.
*/
private boolean isPeak(Peak[] series, int index) {
boolean ok = false;
int current = index;
int okValues = 0;
// values to left
while (!ok) {
current--;
if (current < 0)
return false;
if (!isOk(series, current, index))
return false;
okValues++;
if (okValues > numberOfNeighbours)
ok = true;
}
ok = false;
current = index;
okValues = 0;
// values to right
while (!ok) {
current++;
if (current >= series.length)
return false;
if (!isOk(series, current, index))
return false;
okValues++;
if (okValues > numberOfNeighbours)
ok = true;
}
return true;
}
/**
* In the minimum case this method returns true, if the current value is
* bigger than the index value.
*/
private boolean isOk(Peak[] series, int current, int index) {
if (series[current].getMagnitude() <= series[index].getMagnitude())
return false;
else
return true;
}
}