@Override
public void observe(VectorWritable v) {
Vector x = v.get();
s0++;
if (s1 == null) {
s1 = x.clone();
} else {
s1 = s1.plus(x);
}
if (s2 == null) {
s2 = x.times(x);
} else {
s2 = s2.plus(x.times(x));
}
}
public void reduce(VarLongWritable key, Iterable<VectorWritable> values, Context context)
throws IOException, InterruptedException {
Vector partial = null;
for (VectorWritable vectorWritable : values) {
partial = partial == null ? vectorWritable.get() : partial.plus(vectorWritable.get());
}
context.write(key, new VectorWritable(partial));
}
