Index and MultiIndex

What is an Index?

• Every Pandas Series or DataFrame has an index.
• It labels rows, allowing you to access, slice, and align data.
• By default, a DataFrame gets a RangeIndex (0, 1, 2, …).

Example:

Output:

0,1,2 is the default index.

Custom Index

• You can set a column as the index using .set_index():

Output:

Now the index is Name, which can be used for label-based access:

Output:

Index Properties and Methods

MultiIndex (Hierarchical Index)

• MultiIndex allows multiple levels of indexing in rows or columns.
• Useful for grouped, hierarchical, or panel-like data.
• MultiIndex works well with .groupby(), .pivot_table(), and aggregation.

Creating MultiIndex - from arrays

Output:

Region is level 0, Store is level 1.

Creating MultiIndex - from tuples

Accessing MultiIndex data

Single level:

Output:

Specific row:

Output:

Slicing levels:

Resetting and swapping levels

Sorting MultiIndex