'Compare two dataframes and write the differences to another dataframe

I have two dataframes. df1 and df2

import pandas as pd

df1 = pd.DataFrame({
'Buyer': ['Carl', 'Alex', 'Lauren'],
'Quantity': [18, 3, 8]})

df2 = pd.DataFrame({
'Buyer': ['Carl', 'Alex', 'Maya', 'Emily'],
'Quantity': [18, 3, 5, 5]})

I was wondering if there was a way to compare df1 with df2 and append whatver is in not df1 to df2 so I will have an end result like

df2 = pd.DataFrame({
'Buyer': ['Carl', 'Alex', 'Maya', 'Emily', 'Lauren'],
'Quantity': [18, 3, 5, 5, 8]})

Solution 1:^[1]

You just need to concat the two dfs and then drop dupes

df2 = pd.concat([df1,df2]).drop_duplicates()

>>> df2
    Buyer  Quantity
0    Carl        18
1    Alex         3
2  Lauren         8
2    Maya         5
3   Emily         5

Solution 2:^[2]

Combine them like you said (append) and then just do a drop duplicate:

import pandas as pd

df1 = pd.DataFrame({
'Buyer': ['Carl', 'Alex', 'Lauren'],
'Quantity': [18, 3, 8]})

df2 = pd.DataFrame({
'Buyer': ['Carl', 'Alex', 'Maya', 'Emily'],
'Quantity': [18, 3, 5, 5]})

df = df1.append(df2)

df = df.drop_duplicates()

print(df)

output:

    Buyer  Quantity
0    Carl        18
1    Alex         3
2    Maya         5
3   Emily         5
4  Lauren         8

Solution 3:^[3]

Using merge it can be achieved.

res = pd.merge(df2,df1,on=['Buyer','Quantity'],how='outer')

output:

Buyer   Quantity
0   Carl    18
1   Alex    3
2   Maya    5
3   Emily   5
4   Lauren  8

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Boskosnitch
Solution 2	Simon
Solution 3

'Compare two dataframes and write the differences to another dataframe

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Sources

Related Questions

Solution 1:^[1]

Solution 2:^[2]

Solution 3:^[3]