/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* RandomAssigner.java
* Random order assignment for K-Means
* Copyright (C) 2004 Misha Bilenko, Sugato Basu
*
*/
package weka.clusterers.assigners;
import java.io.*;
import java.util.*;
import weka.core.*;
import weka.clusterers.*;
public class RandomAssigner extends MPCKMeansAssigner {
/** Move points in assignment step till stabilization? */
protected boolean m_MovePointsTillAssignmentStabilizes = false;
/** Number of times points are moved in assignment step till stabilization */
protected int m_MaxTimesPointsMoved = 100;
/** This is a sequential assignment method */
public boolean isSequential() {
return true;
}
/** The main method
* @return the number of points that changed assignment
*/
public int assign() throws Exception {
int moved = 0;
Instances instances = m_clusterer.getInstances();
int numInstances = instances.numInstances();
Random random = new Random(m_clusterer.getRandomSeed()); // initialize random number generator
int [] indices = new int[numInstances];
for (int i=0; i<numInstances; i++) {
indices[i] = i; // initialize
}
for (int i = numInstances - 1; i > 0; i--) {
int indexToSwap = random.nextInt(i+1);
int temp = indices[i]; // swap
indices[i] = indices[indexToSwap];
indices[indexToSwap] = temp;
}
for (int i=0; i<numInstances; i++) {
try {
// Update number of points moved
moved += m_clusterer.assignInstanceToClusterWithConstraints(indices[i]);
}
catch (Exception e) {
System.out.println("Could not find distance. Exception: " + e);
e.printStackTrace();
}
}
// iterate?
if (m_MovePointsTillAssignmentStabilizes) {
int newMoved = -1;
for (int t=0; t<m_MaxTimesPointsMoved && newMoved != 0; t++) { // move points till assignment stabilizes
newMoved = 0;
m_clusterer.resetObjective();
for (int i = numInstances - 1; i > 0; i--) {
int indexToSwap = random.nextInt(i+1);
int temp = indices[i]; // swap
indices[i] = indices[indexToSwap];
indices[indexToSwap] = temp;
}
for (int i=0; i<numInstances; i++) {
newMoved += m_clusterer.assignInstanceToClusterWithConstraints(indices[i]);
}
if (newMoved > 0) {
System.out.println(newMoved + " points moved on changing order in t=" + t);
} else {
break; // go out of for loop
}
}
}
return moved;
}
/**
* Get/Set m_MovePointsTillAssignmentStabilizes
* @param b truth value
*/
public void setMovePointsTillAssignmentStabilizes (boolean b) {
this.m_MovePointsTillAssignmentStabilizes = b;
}
public boolean getMovePointsTillAssignmentStabilizes () {
return m_MovePointsTillAssignmentStabilizes;
}
/** Get/set the number of times points can be moved */
public int getMaxTimesPointsMoved() {
return m_MaxTimesPointsMoved;
}
public void setMaxTimesPointsMoved(int v) {
this.m_MaxTimesPointsMoved = v;
}
public void setOptions (String[] options)
throws Exception {
// TODO
}
public Enumeration listOptions () {
// TODO
return null;
}
public String [] getOptions () {
String[] options = new String[20];
int current = 0;
if (m_MovePointsTillAssignmentStabilizes) {
options[current++] = "-move";
options[current++] = "" + getMaxTimesPointsMoved();
}
while (current < options.length) {
options[current++] = "";
}
return options;
}
}