/*
* 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.operator.learner.functions.kernel.functions;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/** Stores all distances in a map. Uses only a fixed maximum amount of
* entries for this map (default: 10,000,000, enough for about 3000 examples).
*
* @author Ingo Mierswa
* @version $Id: MapBasedCache.java,v 1.4 2008/09/12 10:29:39 tobiasmalbrecht Exp $
*/
public class MapBasedCache implements KernelCache {
private int maxSize = 10000000;
private int exampleSetSize;
private int accessCounter = 0;
private Map<Integer,Integer> accessMap;
private Map<Integer,Double> entries;
public MapBasedCache(int exampleSetSize) {
this(10000000, exampleSetSize);
}
public MapBasedCache(int maxSize, int exampleSetSize) {
this.maxSize = maxSize;
this.exampleSetSize = exampleSetSize;
this.accessMap = new HashMap<Integer,Integer>(maxSize);
this.entries = new HashMap<Integer,Double>(maxSize);
}
public double get(int i, int j) {
accessCounter++;
Double result = entries.get(i * exampleSetSize + j);
if (result == null) {
return Double.NaN;
} else {
accessMap.put(i * exampleSetSize + j, accessCounter);
return result;
}
}
public void store(int i, int j, double value) {
if (accessMap.size() > this.maxSize) {
System.out.println("Clean cache!");
int oldestKey = -1;
int oldestAcess = Integer.MAX_VALUE;
Iterator<Map.Entry<Integer,Integer>> it = accessMap.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<Integer,Integer> entry = it.next();
int access = entry.getValue();
if (access < oldestAcess) {
oldestKey = entry.getKey();
oldestAcess = access;
}
}
if (oldestKey != -1) {
accessMap.remove(oldestKey);
entries.remove(oldestKey);
}
}
accessMap.put(i * exampleSetSize + j, accessCounter);
entries.put(i * exampleSetSize + j, value);
}
}