@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; }