@Override
public void reduce(IntWritable outRow,
Iterator<DistributedRowMatrix.MatrixEntryWritable> it,
OutputCollector<IntWritable, VectorWritable> out,
Reporter reporter) throws IOException {
RandomAccessSparseVector tmp = new RandomAccessSparseVector(newNumCols, 100);
while (it.hasNext()) {
DistributedRowMatrix.MatrixEntryWritable e = it.next();
tmp.setQuick(e.getCol(), e.getVal());
}
SequentialAccessSparseVector outVector = new SequentialAccessSparseVector(tmp);
out.collect(outRow, new VectorWritable(outVector));
}