[Python] How to flatten nested lists using pandas groupby

My pandas DataFrame has a column with lists dtype. I'd like to Group By and aggregate the DataFrame and flatten the lists.

Here's a sample DataFrame:

import pandas as pd

df = pd.DataFrame({
'id': [1, 1, 2],
'cat': ['A','A','B'],
'lst': [['l0','l1','l2'],['l3','l4'],['lb']],
'v': [10, 20, 10]
})


Use mean to aggregate column v.

Expected output:

id cat lst v

1 A ['l0','l1','l2','l3','l4'] 15
2 B ['lb'] 10

Continue reading...