@Override
public void map(Chunk[] ix, NewChunk[] ncs) {
final Vec[] vecs = new Vec[_cols.length];
final Vec anyv = _base.anyVec();
final long nrow = anyv.length();
long r = ix[0].at80(0);
int last_ci = anyv.elem2ChunkIdx(r < nrow ? r : 0); // memoize the last chunk index
long last_c0 = anyv._espc[last_ci]; // ... last chunk start
long last_c1 = anyv._espc[last_ci + 1]; // ... last chunk end
Chunk[] last_cs = new Chunk[vecs.length]; // ... last chunks
for (int c = 0; c < _cols.length; c++) {
vecs[c] = _base.vecs()[_cols[c]];
last_cs[c] = vecs[c].elem2BV(last_ci);
}
for (int i = 0; i < ix[0]._len; i++) {
// select one row
r = ix[0].at80(i) - 1; // next row to select
if (r < 0) continue;
if (r >= nrow) {
for (int c = 0; c < vecs.length; c++) ncs[c].addNum(Double.NaN);
} else {
if (r < last_c0 || r >= last_c1) {
last_ci = anyv.elem2ChunkIdx(r);
last_c0 = anyv._espc[last_ci];
last_c1 = anyv._espc[last_ci + 1];
for (int c = 0; c < vecs.length; c++) last_cs[c] = vecs[c].elem2BV(last_ci);
}
for (int c = 0; c < vecs.length; c++) ncs[c].addNum(last_cs[c].at(r));
}
}
}
