instance = (Instance) instanceItr.next();
v = (SparseVector) (instance.getData());
indices = v.getIndices();
if (indices != null) {
hIndices.addAll(indices);
if (indices[indices.length - 1] > maxSparseIndex)
maxSparseIndex = indices[indices.length - 1];
} else // dense
if (v.numLocations() > maxDenseIndex)