/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
**********************************************************************************************************************/
package eu.stratosphere.example.java.clustering.util;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.DecimalFormat;
import java.util.Locale;
import java.util.Random;
import eu.stratosphere.example.java.clustering.KMeans;
/**
* Generates data for the {@link KMeans} example program.
*/
public class KMeansDataGenerator {
static {
Locale.setDefault(Locale.US);
}
private static final String CENTERS_FILE = "centers";
private static final String POINTS_FILE = "points";
private static final long DEFAULT_SEED = 4650285087650871364L;
private static final double DEFAULT_VALUE_RANGE = 100.0;
private static final double RELATIVE_STDDEV = 0.08;
private static final int DIMENSIONALITY = 2;
private static final DecimalFormat FORMAT = new DecimalFormat("#0.00");
private static final char DELIMITER = ' ';
/**
* Main method to generate data for the {@link KMeans} example program.
* <p>
* The generator creates to files:
* <ul>
* <li><code>{tmp.dir}/points</code> for the data points
* <li><code>{tmp.dir}/centers</code> for the cluster centers
* </ul>
*
* @param args
* <ol>
* <li>Int: Number of data points
* <li>Int: Number of cluster centers
* <li><b>Optional</b> Double: Standard deviation of data points
* <li><b>Optional</b> Double: Value range of cluster centers
* <li><b>Optional</b> Long: Random seed
* </ol>
*/
public static void main(String[] args) throws IOException {
// check parameter count
if (args.length < 2) {
System.out.println("KMeansDataGenerator <numberOfDataPoints> <numberOfClusterCenters> [<relative stddev>] [<centroid range>] [<seed>]");
System.exit(1);
}
// parse parameters
final int numDataPoints = Integer.parseInt(args[0]);
final int k = Integer.parseInt(args[1]);
final double stddev = args.length > 2 ? Double.parseDouble(args[2]) : RELATIVE_STDDEV;
final double range = args.length > 3 ? Double.parseDouble(args[4]) : DEFAULT_VALUE_RANGE;
final long firstSeed = args.length > 4 ? Long.parseLong(args[4]) : DEFAULT_SEED;
final double absoluteStdDev = stddev * range;
final Random random = new Random(firstSeed);
final String tmpDir = System.getProperty("java.io.tmpdir");
// the means around which data points are distributed
final double[][] means = uniformRandomCenters(random, k, DIMENSIONALITY, range);
// write the points out
BufferedWriter pointsOut = null;
try {
pointsOut = new BufferedWriter(new FileWriter(new File(tmpDir+"/"+POINTS_FILE)));
StringBuilder buffer = new StringBuilder();
double[] point = new double[DIMENSIONALITY];
int nextCentroid = 0;
for (int i = 1; i <= numDataPoints; i++) {
// generate a point for the current centroid
double[] centroid = means[nextCentroid];
for (int d = 0; d < DIMENSIONALITY; d++) {
point[d] = (random.nextGaussian() * absoluteStdDev) + centroid[d];
}
writePoint(point, buffer, pointsOut);
nextCentroid = (nextCentroid + 1) % k;
}
}
finally {
if (pointsOut != null) {
pointsOut.close();
}
}
// write the uniformly distributed centers to a file
BufferedWriter centersOut = null;
try {
centersOut = new BufferedWriter(new FileWriter(new File(tmpDir+"/"+CENTERS_FILE)));
StringBuilder buffer = new StringBuilder();
double[][] centers = uniformRandomCenters(random, k, DIMENSIONALITY, range);
for (int i = 0; i < k; i++) {
writeCenter(i + 1, centers[i], buffer, centersOut);
}
}
finally {
if (centersOut != null) {
centersOut.close();
}
}
System.out.println("Wrote "+numDataPoints+" data points to "+tmpDir+"/"+POINTS_FILE);
System.out.println("Wrote "+k+" cluster centers to "+tmpDir+"/"+CENTERS_FILE);
}
private static final double[][] uniformRandomCenters(Random rnd, int num, int dimensionality, double range) {
final double halfRange = range / 2;
final double[][] points = new double[num][dimensionality];
for (int i = 0; i < num; i++) {
for (int dim = 0; dim < dimensionality; dim ++) {
points[i][dim] = (rnd.nextDouble() * range) - halfRange;
}
}
return points;
}
private static void writePoint(double[] coordinates, StringBuilder buffer, BufferedWriter out) throws IOException {
buffer.setLength(0);
// write coordinates
for (int j = 0; j < coordinates.length; j++) {
buffer.append(FORMAT.format(coordinates[j]));
if(j < coordinates.length - 1) {
buffer.append(DELIMITER);
}
}
out.write(buffer.toString());
out.newLine();
}
private static void writeCenter(long id, double[] coordinates, StringBuilder buffer, BufferedWriter out) throws IOException {
buffer.setLength(0);
// write id
buffer.append(id);
buffer.append(DELIMITER);
// write coordinates
for (int j = 0; j < coordinates.length; j++) {
buffer.append(FORMAT.format(coordinates[j]));
if(j < coordinates.length - 1) {
buffer.append(DELIMITER);
}
}
out.write(buffer.toString());
out.newLine();
}
}