python pandas DataFrame 转置

import pandas as pd

df1 = pd.DataFrame(
    {
        '日期': ['2021-7-2', '2021-8-2', '2021-9-2', '2021-10-2'],
        'A': [1, 2, 3, 4],
        'B': [5, 6, 7, 8],
        'C': [9, 10, 11, 12],
        'D': [13, 14, 15, 16]
    },
    index=[0, 1, 2, 3])
print(df1)

          日期  A  B   C   D
0   2021-7-2  1  5   9  13
1   2021-8-2  2  6  10  14
2   2021-9-2  3  7  11  15
3  2021-10-2  4  8  12  16

df2 = df1.T  # 转置
print(df2)

           0         1         2          3
日期  2021-7-2  2021-8-2  2021-9-2  2021-10-2
A          1         2         3          4
B          5         6         7          8
C          9        10        11         12
D         13        14        15         16