@Override
protected void setup(Reducer.Context context) throws IOException, InterruptedException {
super.setup(context);
Configuration conf = context.getConfiguration();
iteration = conf.getInt("iteration", -1);
System.out.println("Setting up Reducer " + iteration);
centroids = KMeansUtil.readCentroids(conf);
System.out.println("Reducer " + iteration + " Received " + centroids.size() + " centroids as");
KMeansUtil.showOutput(centroids);
}
@Override
protected void reduce(IntWritable key, Iterable<LongWritable> values, Context context)
throws IOException, InterruptedException {
Double currentCentroid = centroids.get(key.get());
System.out.println("Reducer " + iteration + " Current Centroid: " + currentCentroid);
Double newCentroid = getNewCentroid(values);
System.out.println(
"Reducer "
+ iteration
+ " Reducer for centroid "
+ key.get()
+ " which is "
+ centroids.get(key.get()));
if (newCentroid != null) {
System.out.println(
"Reducer "
+ iteration
+ " New centroid calculated for "
+ key.get()
+ " is "
+ newCentroid);
if (belowThreshold(currentCentroid, newCentroid)) {
context.getCounter(Convergence.CONVERGENT).increment(1);
System.out.println(
"Reducer "
+ iteration
+ " REDUCER CONVERGED!"
+ context.getCounter(Convergence.CONVERGENT).getValue()
+ " times");
}
context = KMeansUtil.writeCentroid(context, key.get(), newCentroid);
DoubleWritable op = new DoubleWritable(newCentroid);
context.write(key, op);
} else {
System.out.println("Reducer " + iteration + " New Centroid calculated is NULL!");
}
}
