如何删除具有空值的特定行

问题描述：

这是我拥有的数据帧的子集.对于句子列具有值的每一行，在接下来的两行中重复A B C D列，而句子列没有值.如何删除句子中具有空值的第二行.我需要将句子列的第一行保留为空值.

This is a subset of data frame that I have. For each row that sentence column has value, column A B C D are repeated for the next two rows without having a value for the sentence column. How can I remove the second row with null value for sentences. I need to keep the first row with null value for sentence column.

     A    B   C    D             R      sentence              ADR 
    112 135 21  EffexorXR.21    1    lack of good feeling.    good
    113 135 21  EffexorXR.21    1                               1 
    114 135 21  EffexorXR.21    1   
    115 136 21  EffexorXR.21    2   Feel disconnected         disconnected
    116 136 21  EffexorXR.21    2        
    117 136 21  EffexorXR.21    2    
    118 142 22  EffexorXR.22    1   Weight gain                gain
    119 142 22  EffexorXR.22    1                                1
    120 142 22  EffexorXR.22    1

输出是这样

   A    B   C    D             R        sentence               ADR     
    112 135 21  EffexorXR.21    1    lack of good feeling.     good
    113 135 21  EffexorXR.21    1                               1
    115 136 21  EffexorXR.21    2    Feel disconnected        disconnected       
    116 136 21  EffexorXR.21    2   
    118 142 22  EffexorXR.22    1    Weight gain               gain
    119 142 22  EffexorXR.22    1                               1

如果我使用以下代码:

df = df[pd.notnull(df['sentences'])]，然后它将删除具有空值的两行.有什么建议吗?

df = df[pd.notnull(df['sentences'])], Then It will remove both rows with null values. Any suggestion ?

以下解决方案不起作用.

The following solution does not work.

df.set_index('A').drop_duplicates().reset_index()

答

也许您可以看到合并列的重复并将其用于mask原始dataframe:

May be you can see duplicates of combined columns and use it to mask original dataframe:

new_df = df[~df[['B','C','D', 'R', 'sentence']].duplicated()]
print(new_df)

输出:

     A    B   C             D  R               sentence           ADR
0  112  135  21  EffexorXR.21  1  lack of good feeling.          good
1  113  135  21  EffexorXR.21  1                                    1
3  115  136  21  EffexorXR.21  2      Feel disconnected  disconnected
4  116  136  21  EffexorXR.21  2                                     
6  118  142  22  EffexorXR.22  1            Weight gain          gain
7  119  142  22  EffexorXR.22  1                                    1

如何删除具有空值的特定行

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