熊猫：从另一个数据框中的列值插入数据框中的行

Question

我有两个带有数据的多索引数据框，如下所示：

df1：

                                                             qty
plot name sub plot name        crop          date                   
BL1       Cabbage-041221       Cabbage       2022-03-01    36.000000
                                             2022-03-02    29.900000
                                             2022-03-03    51.799999
                                             2022-03-16    48.000000
          Cluster Beans-110222 Cluster Beans 2022-04-15     5.500000
                                             2022-04-19     2.500000
          Musk Melon-050222    Musk Melon    2022-04-05    21.100000
          Tomato-050222        Tomato        2022-04-14    39.000000
BL2       Green Tomato-180122  Green Tomato  2022-03-15     7.500000
                                             2022-03-16     5.100000
                                             2022-03-17     3.700000
          Ladies Finger-191121 Ladies Finger 2022-03-02    12.600000
                                             2022-03-03     9.200000
                                             2022-03-04     7.200000
                                             2022-03-05     7.600000
Totals                                                  35199.440001

和df2：

                                                qty
plot name sub plot name        crop                      
BL1       Cabbage-041221       Cabbage         606.900003
          Cluster Beans-110222 Cluster Beans     8.000000
          Musk Melon-050222    Musk Melon       21.100000
          Tomato-050222        Tomato           39.000000
BL2       Green Tomato-180122  Green Tomato     27.200000
          Ladies Finger-191121 Ladies Finger    93.100000
          Ladies Finger-290122 Ladies Finger   139.650002

我需要将两个数据框组合起来，这样我就可以为每个作物类别在 df1 中添加一行，其中 df2 中的 qty 值如下：

                                                           qty
plot name sub plot name        crop          date                   
BL1       Cabbage-041221       Cabbage       2022-03-01    36.000000
                                             2022-03-02    29.900000
                                             2022-03-03    51.799999
                                             2022-03-16    48.000000
                                             Subtotal      606.900003
          Cluster Beans-110222 Cluster Beans 2022-04-15     5.500000
                                             2022-04-19     2.500000
                                             Subtotal       8.000000
          Musk Melon-050222    Musk Melon    2022-04-05    21.100000
                                             Subtotal      21.100000
          Tomato-050222        Tomato        2022-04-14    39.000000
                                             Subtotal      39.000000
BL2       Green Tomato-180122  Green Tomato  2022-03-15     7.500000
                                             2022-03-16     5.100000
                                             2022-03-17     3.700000
                                             Subtotal      27.200000
          Ladies Finger-191121 Ladies Finger 2022-03-02    12.600000
                                             2022-03-03     9.200000
                                             2022-03-04     7.200000
                                             2022-03-05     7.600000
                                             Subtotal      93.100000
Totals                                                  35199.440001

如何在不丢失多索引的情况下执行此操作？ df2 是通过在 df1 上应用 groupby 获得的，如下所示：

df2 = (df1.drop('Totals', level=0)
.groupby(level=list(range(df1.index.nlevels-1))).sum())

Answer 1

在df2中使用值Subtotal创建一个新列date ，然后连接两个数据框和排序索引：

out = (pd.concat([df1, df2.assign(date='Subtotal').set_index('date', append=True)])
         .sort_index())

输出：

>>> out
                                                                  qty
plot name sub plot name        crop          date                    
BL1       Cabbage-041221       Cabbage       2022-03-01     36.000000
                                             2022-03-02     29.900000
                                             2022-03-03     51.799999
                                             2022-03-16     48.000000
                                             Subtotal      606.900003
          Cluster Beans-110222 Cluster Beans 2022-04-15      5.500000
                                             2022-04-19      2.500000
                                             Subtotal        8.000000
          Musk Melon-050222    Musk Melon    2022-04-05     21.100000
                                             Subtotal       21.100000
          Tomato-050222        Tomato        2022-04-14     39.000000
                                             Subtotal       39.000000
BL2       Green Tomato-180122  Green Tomato  2022-03-15      7.500000
                                             2022-03-16      5.100000
                                             2022-03-17      3.700000
                                             Subtotal       27.200000
          Ladies Finger-191121 Ladies Finger 2022-03-02     12.600000
                                             2022-03-03      9.200000
                                             2022-03-04      7.200000
                                             2022-03-05      7.600000
                                             Subtotal       93.100000
          Ladies Finger-290122 Ladies Finger Subtotal      139.650002
Totals    NaN                  NaN           NaN         35199.440001