In this chapter, we will cover the following topics:

• Defining an aggregation
• Grouping and aggregating with multiple columns and functions
• Removing the MultiIndex after grouping
• Customizing an aggregation function
• Customizing aggregating functions with *args and **kwargs
• Examining the groupby object
• Filtering for states with a minority majority
• Transforming through a weight loss bet
• Calculating weighted mean SAT scores per state with apply
• Grouping by continuous variables
• Counting the total number of flights between cities
• Finding the longest streak of on-time flights