@Override
public void notify(final CentroidPairing<Object> pairing) {
outputKeyWritable.set(pairing.getCentroid().getGroupID());
final double extraFromItem[] = pairing.getPairedItem().getDimensionValues();
final double extraCentroid[] = pairing.getCentroid().getDimensionValues();
final Point p = centroidExtractor.getCentroid(pairing.getPairedItem().getWrappedItem());
final Point centroid =
centroidExtractor.getCentroid(pairing.getCentroid().getWrappedItem());
// calculate error for dp
// using identity matrix for the common covariance, therefore
// E[(p - c)^-1 * cov * (p - c)] => (px - cx)^2 + (py - cy)^2
double expectation = 0.0;
for (int i = 0; i < extraCentroid.length; i++) {
expectation += Math.pow(extraFromItem[i] - extraCentroid[i], 2);
}
expectation +=
(Math.pow(p.getCoordinate().x - centroid.getCoordinate().x, 2)
+ Math.pow(p.getCoordinate().y - centroid.getCoordinate().y, 2));
// + Math.pow(
// p.getCoordinate().z - centroid.getCoordinate().z,
// 2));
outputValWritable.set(expectation, 1);
}
@Override
public void reduce(
final Text key,
final Iterable<CountofDoubleWritable> values,
final Reducer<Text, CountofDoubleWritable, Text, CountofDoubleWritable>.Context context)
throws IOException, InterruptedException {
double expectation = 0;
double ptCount = 0;
for (final CountofDoubleWritable value : values) {
expectation += value.getValue();
ptCount += value.getCount();
}
outputValue.set(expectation, ptCount);
context.write(key, outputValue);
}