groupby()

groupby() lets you split your data into groups and then perform operations on each group separately.

Basic Example:

import pandas as pd

df = pd.DataFrame({
    'Name': ['Alice', 'Bob', 'Alice', 'Bob', 'Alice'],
    'Subject': ['Math', 'Math', 'English', 'English', 'Science'],
    'Score': [85, 78, 92, 88, 90]
})

df.groupby('Name')['Score'].mean()

Result:

Name
Alice    89.0
Bob      83.0

lost? ~ Index - Data Engineering