@Override
protected long[] inferOutputCharacteristics(MemoTable memo) {
long[] ret = null;
Hop input = getInput().get(0);
MatrixCharacteristics mc = memo.getAllInputStats(input);
if (_direction == Direction.Col && mc.colsKnown()) ret = new long[] {1, mc.getCols(), -1};
else if (_direction == Direction.Row && mc.rowsKnown()) ret = new long[] {mc.getRows(), 1, -1};
return ret;
}
