df = pd.DataFrame({'A': ['a', 'b', 'b', 'a', 'a', 'b', 'b', 'a'], 'B': [2, 8, 1, 4, 3, 2, 5, 9], 'C': [102, 98, 107, 104, 115, 87, 92, 123], 'D':[20200102,20200103,20200104,20200105,20200106,20200107,20200108,20200109], 'F':[15,25,31,26,98,17,25,69]})