如何通過連接新數據在每個類別的頂部添加一行？

Question

我有 2 個不同大小的數據集（CSV 格式），如下所示：

df_old：

index category  text
 0    spam      you win much money
 1    spam      you win 7000 car
 2    spam      you are the winner of the game
 3    not_spam  the weather in Chicago is nice
 4    not_spam  Paris is the capital of France
 5    not_spam  pizza is an Italian food
 6    neutral   we have a party now
 7    neutral   they are driving to downtown
 

df_new：

index category  text
 12   spam      we are the cheapest insurance
 14   spam      London is the capital of Canada
 15   not_spam  no more raining in winter
 25   not_spam  the soccer game plays on HBO
 31   neutral   construction will be done
 

我想將df_new連接到df_old ，但是df_new位於df_old的每個類別之上。 預期的 output 應該是：

df_concat：

index category  text
 12   spam      we are the cheapest insurance
 14   spam      London is the capital of Canada
 0    spam      you win much money
 1    spam      you win 7000 car
 2    spam      you are the winner of the game
 15   not_spam  no more raining in winter
 25   not_spam  the soccer game plays on HBO
 3    not_spam  the weather in Chicago is nice
 4    not_spam  Paris is the capital of France
 5    not_spam  pizza is an Italian food
 31   neutral   construction will be done
 6    neutral   we have a party now
 7    neutral   they are driving to downtown

我試過了，但這不是我想要的，因為它將所有內容都添加到頂部，而不是每個類別。

Answer 1

你可以試試：

(pd.concat([df_new,df_old], sort=False)
   .sort_values('category', ascending=False, kind='mergesort')
)

Output：

   index  category                             text
0     12      spam    we are the cheapest insurance
1     14      spam  London is the capital of Canada
0      0      spam               you win much money
1      1      spam                 you win 7000 car
2      2      spam   you are the winner of the game
2     15  not_spam        no more raining in winter
3     25  not_spam     the soccer game plays on HBO
3      3  not_spam   the weather in Chicago is nice
4      4  not_spam   Paris is the capital of France
5      5  not_spam         pizza is an Italian food
4     31   neutral        construction will be done
6      6   neutral              we have a party now
7      7   neutral     they are driving to downtown