In this chapter, we took a deeper dive into using indexes in pandas to organize and retrieve data. We examined many of the useful types of indexes and how they can be used with different types of data to efficiently access values without needing to query data in the rows. And we concluded with an examination of using hierarchical indexes to be able to efficiently retrieve data that match to labels in multiple indexes, giving us a powerful means of being able to select subsets of data.
At this point, we have covered much of the basic modeling portion of pandas. In the next chapter, we will examine to to represent categorical variable with pandas.