我有分组级别为['颜色'，'水果'，'日期'，'值']的数据。

data = pd.DataFrame({'color': ['Green','Green', 'Green', 'Green', 'Red', 'Red'], 
                    'fruit' : ['Banana', 'Banana', 'Apple', 'Apple', 'Banana', 'Apple'],
                    'date': ['2011-01-01', '2011-01-02', '2011-01-01', '2011-01-02', '2011-02-01', '2011-02-01'],
                    'value': [ 1, np.nan, np.nan, 2, 3 , np.nan]})

Output:

Class   fruit   date    value
0   Green   Banana  2011-01-01  1.0
1   Green   Banana  2011-01-02  NaN
2   Green   Apple   2011-01-01  NaN
3   Green   Apple   2011-01-02  2.0
4   Yellow  Banana  2011-02-01  3.0
5   Yellow  Apple   2011-02-01  NaN

我需要填充“值”，而对于日期我们没有数据。因此，此填充将仅限于[“颜色”，“水果”]级别。
我尝试使用df = df.groupby(['color', 'fruit', 'date'])['value'].mean().replace(to_replace=0, method='ffill')填充，但这会将数据溢出到下一个关联的[color，fruit]组

Expected Output:

Class   fruit   date    value
0   Green   Banana  2011-01-01  1.0
1   Green   Banana  2011-01-02  1.0
2   Green   Apple   2011-01-01  NaN
3   Green   Apple   2011-01-02  2.0
4   Yellow  Banana  2011-02-01  3.0
5   Yellow  Apple   2011-02-01  NaN