在python中，如何用空值之前的所有值和空值之后的第一个后续值的平均值来填充空值？

import pandas as pd
import numpy as np

data = pd.DataFrame({'A': [1, 2, np.nan, 4, np.nan, 6, 7, np.nan, 9]})

data['A'] = data['A'].fillna(0)

data['A'] = data['A'].rolling(window=2, min_periods=1).mean()

import pandas as pd
import numpy as np

data = pd.DataFrame({'A': [1, 2, np.nan, 4, np.nan, 6, 7, np.nan, 9]})
data['A'] = data['A'].fillna(0)
data['A'] = data['A'].rolling(window=2, min_periods=1).mean()

print(data)

     A
0  1.0
1  2.0
2  2.0
3  4.0
4  5.0
5  6.0
6  7.0
7  8.0
8  9.0