package com.aamend.hadoop.clustering.cluster;
import com.aamend.hadoop.clustering.distance.DistanceMeasure;
import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.conf.Configuration;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
/**
* Author: antoine.amend@gmail.com
* Date: 21/03/14
*/
public class Canopy implements Cluster {
public static final String MIN_OBSERVATIONS = "min.cluster.observations";
public static final String MIN_SIMILARITY = "min.cluster.similarity";
public static final String CLUSTER_T1 = "cluster.t1";
public static final String CLUSTER_T2 = "cluster.t2";
public static final String CLUSTER_MEASURE = "cluster.measure";
public static final String MAX_DISTANCE = "cluster.max.measure";
public static final String LAST_ITERATION = "cluster.last.iteration";
private int id;
private long num;
private int[] center;
public Canopy(int id, int[] center) {
num = 1;
this.id = id;
this.center = center;
}
public Canopy(int id, int[] center, long num) {
this.id = id;
this.center = center;
this.num = num;
}
@Override
public double pdf(int[] x, DistanceMeasure measure) {
return 1 - measure.distance(center, x);
}
@Override
public void observe(long number) {
num += number;
}
@Override
public void computeCenter(List<int[]> centers, DistanceMeasure measure) {
if (centers.size() <= 1) {
return;
}
double[] averages = new double[centers.size()];
for (int i = 0; i < centers.size(); i++) {
double average = 0.0d;
// Consider center i
// Compute distance to other points
for (int j = 0; j < centers.size(); j++) {
if (j != i) {
average += measure.distance(centers.get(i), centers.get(j));
}
}
averages[i] = average / (centers.size() - 1);
}
double min = Double.MAX_VALUE;
int minIdx = 0;
for (int i = 0; i < averages.length; i++) {
double average = averages[i];
if (average < min) {
min = average;
minIdx = i;
}
}
this.center = centers.get(minIdx);
}
@Override
public int getId() {
return id;
}
@Override
public int[] getCenter() {
return center;
}
@Override
public long getNum() {
return num;
}
@Override
public String asFormattedString() {
StringBuilder sb = new StringBuilder(50);
return sb.append("C-").append(id)
.append(" {n:").append(num)
.append(",c:").append(Arrays.toString(center))
.append("}")
.toString();
}
public static DistanceMeasure configureMeasure(Configuration conf) throws IOException {
String className = conf.get(CLUSTER_MEASURE);
if (StringUtils.isEmpty(className)) {
throw new IllegalArgumentException(
"Distance measure is empty. " +
"It should be specified from Hadoop configuration"
);
}
DistanceMeasure measure;
try {
Class<?> clazz = Class.forName(className);
Object obj = clazz.newInstance();
measure = (DistanceMeasure) obj;
} catch (ClassNotFoundException e) {
throw new IOException(e);
} catch (InstantiationException e) {
throw new IOException(e);
} catch (IllegalAccessException e) {
throw new IOException(e);
}
// Configure distance measure
measure.configure(conf);
return measure;
}
}