Groupby 2 个不同的列 Python Pandas

Question

import pandas as pd

df1 = pd.DataFrame([['Dog', '2017', 100], ['Dog', '2017' ,500],['Dog', '2016' ,200],['Dog', '2016' ,150],['Cat', '2017' ,50],['Cat', '2017' ,100],
['Cat', '2016' ,50]], columns=('Pet','Year','Amount'))

DF1

Pet  Year  Amount
Dog  2017  100
Dog  2017  500
Dog  2016  200
Dog  2016  150
Cat  2017  50
Cat  2017  100
Cat  2016  50

I would like to turn the above dataframe into the following:

DF2

Pet Year Amount
Dog 2017 600
Dog 2016 350
Cat 2017 150
Cat 2016 50

This is grouping by Pet and by Year and summing the amount between them.

Any ideas?

Answer 1

Use groupby with parameters as_index=False for not return MultiIndex and sort=False for avoid sorting:

print (df1.groupby(['Pet','Year'], as_index=False, sort=False).sum())
   Pet  Year  Amount
0  Dog  2017     600
1  Dog  2016     350
2  Cat  2017     150
3  Cat  2016      50