// perform the mapping
for (int i = 0; i < RAW.length; i++) {
Vector vector = new RandomAccessSparseVector(RAW[i].length);
vector.assign(RAW[i]);
mapper.map(new IntWritable(i), new VectorWritable(vector), context);
}
// check the results
assertEquals("Number of map results", RAW.length, writer.getData().size());
for (int i = 0; i < RAW.length; i++) {