查找两个整数列之间的差异，但按特定 ID 列 [重复]

Question

我有以下两个数据框。

last_request_df：

name    fruit_id  sold
apple   123       1 
melon   456       12
banana  12        23

current_request_df：

name    fruit_id  sold
apple   123       5 
melon   456       19
banana  12        43
orange  55        3 
mango   66        0 

输出应基于匹配 last_request_df 和 current_request_df 中的 fruit_id 列并找出已售列中的差异：

差异_df：

name    fruit_id  sold
apple   123       4 
melon   456       7
banana  12        20
orange  55        3 
mango   66        0

我尝试了以下方法，但恐怕这与 fruid_id 列不匹配。

difference_df['sold_diff'] = current_request_df['sold'] - last_request_df['sold'] 

是否有根据我提供的数据捕获差异的首选方法？

Answer 1

 #Reset index to name for both dfs

 difference_df=current_request_df.set_index('name')
 last_request_df=last_request_df.set_index('name')
     

#Find the difference using sub. To do this ensure the two dfs have same index by reindexing 

difference_df['sold']=difference_df['sold'].sub(last_request_df.reindex(index=difference_df.index).fillna(0)['sold'])
    

  

         fruit_id  sold
name                  
apple        123   4.0
melon        456   7.0
banana        12  20.0
orange        55   3.0
mango         66   0.0