Swapping index levels in Pandas - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does swapping index levels mean in pandas?

Swapping index levels means changing the order of the levels in a MultiIndex, so the level that was first becomes second, and vice versa.

beginner

Which pandas method is used to swap index levels?

The method used is swaplevel(). It switches the positions of two index levels in a MultiIndex.

beginner

How do you swap the first and second index levels of a DataFrame named df?

Use df.swaplevel(0, 1). This swaps the index levels at position 0 and 1.

intermediate

What happens if you swap index levels but do not sort the index afterwards?

The index order might look unordered or confusing. Sorting with sort_index() after swapping helps keep the data organized.

intermediate

Can you swap index levels on both rows and columns in pandas?

Yes. You can swap index levels on rows (index) or columns (columns MultiIndex) by specifying the axis in swaplevel().

What does df.swaplevel(0, 1) do in pandas?

A Swaps the first and second index levels of df

B Swaps the first and second columns of df

C Sorts the index of df

D Resets the index of df

The swaplevel() method swaps two index levels. Here, levels 0 and 1 are swapped.

Which method should you use after swapping index levels to keep the index ordered?

A reset_index()

B sort_index()

C drop_duplicates()

D groupby()

After swapping index levels, sort_index() helps reorder the index for clarity.

If a DataFrame has a MultiIndex on columns, how do you swap its levels?

A Use <code>swaplevel()</code> with <code>axis=0</code>

B Use <code>sort_values()</code>

C Use <code>reset_index()</code>

D Use <code>swaplevel()</code> with <code>axis=1</code>

Columns are on axis 1, so swapping their index levels requires axis=1.

What type of index must a DataFrame have to use swaplevel()?

A MultiIndex with at least two levels

B Single-level index

C No index

D DatetimeIndex only

swaplevel() works only if there are at least two index levels to swap.

What is the default axis for swaplevel() in pandas?

A axis=2

B axis=1 (columns)

C axis=0 (rows)

D axis=None

By default, swaplevel() swaps index levels on rows (axis=0).

Explain how to swap two index levels in a pandas DataFrame and why you might want to do this.

Think about changing the order of row labels in a table.

Describe the steps to swap column index levels in a pandas DataFrame with a MultiIndex on columns.

Remember columns are on axis 1.