Python Pandas 在两个键上合并两个数据帧并得到总数

Question

I have two dfs

F1_ID	F2_ID	Event_ID	Date
a1	b2	ab4	5/12/21
a2	b3	ab5	5/12/21
b2	a1	ab4	5/12/21
b3	a2	ab5	5/12/21

the second df has a lot more information on it so I am going to show a filtered version of it.

F1_ID	Event_Name	F2_ID	Event_ID	Date	stats	amount	F1_str_total	F2_str_total
a1	Test	b2	ab1	5/8/21	12	41	13	17
a2	Test1	b3	ab2	5/8/21	16	42	12	54
b2	Test	a1	ab1	5/8/21	-12	-41	0	7
b3	Test1	a2	ab2	5/8/21	-16	-42	87	97

I would like to append the details in df1 to df2 and put None in the missing columns but im not sure how to do this.

Expected Output:

F1_ID	Event_Name	F2_ID	Event_ID	Date	stats	amount	F1_str_total	F2_str_total
a1	Test	b2	ab1	5/8/21	12	41	13	17
a2	Test1	b3	ab2	5/8/21	16	42	12	54
b2	Test	a1	ab1	5/8/21	-12	-41	0	7
b3	Test1	a2	ab2	5/8/21	-16	-42	87	97
a1	None	b2	ab4	5/12/21	None	None	None	None
a2	None	b3	ab5	5/12/21	None	None	None	None
b2	None	a1	ab4	5/12/21	None	None	None	None
b3	None	a2	ab%	5/12/21	None	None	None	None

Answer 1

Simply use pandas.DataFrame.append()

df2 = df2.append(df1, ignore_index=True)

print(df2)

  F1_ID Event_Name F2_ID Event_ID     Date  stats  amount  F1_str_total  \
0    a1       Test    b2      ab1   5/8/21   12.0    41.0          13.0   
1    a2      Test1    b3      ab2   5/8/21   16.0    42.0          12.0   
2    b2       Test    a1      ab1   5/8/21  -12.0   -41.0           0.0   
3    b3      Test1    a2      ab2   5/8/21  -16.0   -42.0          87.0   
4    a1        NaN    b2      ab4  5/12/21    NaN     NaN           NaN   
5    a2        NaN    b3      ab5  5/12/21    NaN     NaN           NaN   
6    b2        NaN    a1      ab4  5/12/21    NaN     NaN           NaN   
7    b3        NaN    a2      ab5  5/12/21    NaN     NaN           NaN   

   F2_str_total  
0          17.0  
1          54.0  
2           7.0  
3          97.0  
4           NaN  
5           NaN  
6           NaN  
7           NaN 

Or you can use pandas.concat()

df2 = pd.concat([df2, df1], ignore_index=True)