Selection with a MultiIndex – A single level

A pd.MultiIndex is a subclass of a pd.Index that supports hierarchical labels. Depending on who you ask, this can be one of the best or one of the worst features of pandas. After reading this cookbook, I hope you consider it one of the best.

Much of the derision toward the pd.MultiIndex comes from the fact that the syntax used to select from it can easily become ambiguous, especially when using pd.DataFrame[]. The examples below exclusively use the pd.DataFrame.loc method and avoid pd.DataFrame[] to mitigate confusion.

How to do it

pd.MultiIndex.from_tuples can be used to construct a pd.MultiIndex from a list of tuples. In the following example, we create a pd.MultiIndex with two levels – first_name and last_name, sequentially. We will pair this alongside a very simple pd.Series:

index = pd.MultiIndex.from_tuples([
    ("John", "Smith"),
    ("John", "Doe"),
    (&quot...