如何内爆(回到原来)熊猫字符到由NaN行分隔的单词?

Question

我有一个DataFrame，看起来像这样:

| characters | result |
|:----------:|:------:| 
| b          | TP    |
| a          | TP    | 
| t          | FN    | 
| NaN        | None  | 
| c          | TN    |  
| o          | FP    |  
| p          | TP    |  

我之前把它从"bat"one_answers";cop"。每个单词由NaN行分隔。我想把它们变成DataFrame格式，像这样:

| characters | result | word |
|:----------:|:----- :|:----:|
| b          | TP     | bat  |
| a          | TP     | bat  |
| t          | FN     | bat  |
| NaN        | None   | None |
| c          | TN     | cop  |
| o          | FP     | cop  |
| p          | TP     | cop  |

编辑:请忽略结果列。这里只关心characters和word。原数据框由word列组成，应用熊猫explode()得到characters列。

Answer 1

您可以创建一个自定义组来标识连续的非NaN值，然后连接并映射到原始数据框:

m = df['characters'].isna()
group = (m!=m.shift()).cumsum().mask(m)
to_map = df.groupby(group)['characters'].apply(lambda g: ''.join(g))
df['word'] = group.map(to_map)

输出:

characters result word
0          b     TP  bat
1          a     TP  bat
2          t     FN  bat
3        NaN   None  NaN
4          c     TN  cop
5          o     FP  cop
6          p     TP  cop