package com.aamend.hadoop.clustering.mapreduce;
import com.aamend.hadoop.clustering.cluster.Canopy;
import com.aamend.hadoop.clustering.cluster.CanopyWritable;
import com.aamend.hadoop.clustering.cluster.Cluster;
import com.aamend.hadoop.clustering.distance.DistanceMeasure;
import com.google.common.collect.Lists;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
/**
* Author: antoine.amend@gmail.com
* Date: 21/03/14
*/
public class CanopyCreateMapper extends Mapper<Text, CanopyWritable, Text, CanopyWritable> {
private float t1;
private float t2;
private int nextCanopyId;
private DistanceMeasure measure;
private Collection<Cluster> canopies = Lists.newArrayList();
private static final Text KEY = new Text();
private static final Logger LOGGER = LoggerFactory.getLogger(CanopyCreateMapper.class);
@Override
protected void setup(Context context)
throws IOException, InterruptedException {
// Retrieve params fom configuration
Configuration conf = context.getConfiguration();
measure = Canopy.configureMeasure(conf);
t1 = conf.getFloat(Canopy.CLUSTER_T1, 1.0f);
t2 = conf.getFloat(Canopy.CLUSTER_T2, 0.8f);
}
@Override
protected void map(Text key, CanopyWritable value, Context context) throws IOException, InterruptedException {
Cluster cluster = value.get();
int[] point = cluster.getCenter();
boolean stronglyBound = false;
for (Cluster canopy : canopies) {
double dist = measure.distance(canopy.getCenter(), point);
if (dist < t1) {
KEY.set(Arrays.toString(canopy.getCenter()));
Cluster newCluster;
if (dist < t2) {
newCluster = new Canopy(canopy.getId(), point, value.get().getNum());
LOGGER.debug("Adding (T2) {} to Cluster {}", Arrays.toString(point),
Arrays.toString(canopy.getCenter()));
} else {
newCluster = new Canopy(canopy.getId(), point, 0L);
LOGGER.debug("Adding (T1) {} to Cluster {}", Arrays.toString(point),
Arrays.toString(canopy.getCenter()));
}
context.write(KEY, new CanopyWritable(newCluster));
}
stronglyBound = stronglyBound || dist < t2;
}
if (!stronglyBound) {
nextCanopyId++;
Cluster canopy = new Canopy(nextCanopyId, point, value.get().getNum());
canopies.add(canopy);
LOGGER.debug("Creating a new Cluster {}", canopy.asFormattedString());
KEY.set(Arrays.toString(canopy.getCenter()));
context.write(KEY, value);
}
}
}