python pandas利用fillna方法实现部分自动填充功能

> df = pd.read_excel(r'D:/myExcel/1.xlsx')
> df
  name Chinese Chinese.1  id
0  bob  12.0   12 123.0
1 millor  NaN   32 124.0
2 jiken  89.0   89 NaN
3 jiken  89.0   89 125.0
# 默认将所有值均填充为0
> df.fillna(0)
  name Chinese Chinese.1  id
0  bob  12.0   12 123.0
1 millor  0.0   32 124.0
2 jiken  89.0   89 0.0
3 jiken  89.0   89 125.0

# 也可以通过字典控制每列传什么值
> my_dict = {'Chinese' : 92, 'id' : 98}
> df.fillna(my_dict)
  name Chinese Chinese.1  id
0  bob  12.0   12 123.0
1 millor  92.0   32 124.0
2 jiken  89.0   89 98.0
3 jiken  89.0   89 125.0

# 向下
> df.fillna(method='ffill')
  name Chinese Chinese.1  id
0  bob  12.0   12 123.0
1 millor  12.0   32 124.0
2 jiken  89.0   89 124.0
3 jiken  89.0   89 125.0

# 向上
> df.fillna(method='bfill')
  name Chinese Chinese.1  id
0  bob  12.0   12 123.0
1 millor  89.0   32 124.0
2 jiken  89.0   89 125.0
3 jiken  89.0   89 125.0

# 限制自动填充最大填充1行。
> df.fillna(method = 'bfill', limit=1)
  name Chinese Chinese.1  id
0  bob  12.0   12 123.0
1 millor  89.0   32 124.0
2 jiken  89.0   89 125.0
3 jiken  89.0   89 125.0

> df.isna()
 name Chinese Chinese.1  id
0 False False  False False
1 False  True  False False
2 False False  False True
3 False False  False False
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