python - 从 Pandas 数据框中，如何找到每个用户的重复评论数？

Question

我有包含用户名列表及其评论的数据框，请参见下面的格式。

为每个用户查找重复评论(垃圾邮件)的最快、最有效的方法是什么？

数据框格式:

Author  | Comment
casy    Nice picture! 
linda   I like this 
casy    Nice picture! 
tom     I disagree 
bob     Follow me 
bob     Follow me 
bob     Follow me 
bob     Follow me 
casy    Nice picture! 
casy    Wow! 
linda   Interesting post 
linda   Check my profile
bob     Dissapointing
casy    Wow! 

我想得到以下格式的结果，所以结果表将是:

Author  | Number of dup. comments (descending)  | Comment   
bob     4   Follow me 
casy    3   Nice picture
casy    2   Wow! 
bob     1   Dissapointing 
linda   1   I like this 
linda   1   Check my profile
linda   1   Interesting post 
tom     1   I disagree

Answer 1

使用groupby与 size首先，然后 sort_values , 通过 reset_index 创建列如果需要，最后按 reindex 更改列的顺序:

df = (df.groupby(['Author', 'Comment'], sort=False).size()
       .sort_values(ascending=False)
       .reset_index(name='Number')
       .reindex(columns=['Author','Number','Comment']))
print (df)
  Author  Number           Comment
0    bob       4         Follow me
1   casy       3     Nice picture!
2   casy       2              Wow!
3    bob       1     Dissapointing
4  linda       1  Check my profile
5  linda       1  Interesting post
6    tom       1        I disagree
7  linda       1       I like this