Python Pandas | Rearrange levels using level name in MultiIndex

Learn how to rearrange levels using level name in MultiIndex in Python Pandas?
Submitted by IncludeHelp, on March 27, 2022

In Python Pandas, the MultiIndex object is the hierarchical analogue of the standard Index object which typically stores the axis labels in pandas objects. You can consider that MultiIndex is an array of unique tuples.

The pandas.MultiIndex.from_arrays() method is used to create a MultiIndex, and the names parameter is used to set names of each of the index levels.

Read: Create a MultiIndex with the names of each of the index levels

Rearrange levels using level name in MultiIndex

The pandas.MultiIndex.reorder_levels() method is used to rearrange levels using level name in MultiIndex.

Syntax:

MultiIndex.reorder_levels(order)

The method accepts list representing a new level order that can be either list of int or list of str and return the MultiIndex.

To work with MultiIndex in Python Pandas, we need to import the pandas library. Below is the syntax,

import pandas as pd

Python code to rearrange levels using level name in MultiIndex

# Import the pandas package
import pandas as pd

# Create arrays
employees = [
        ['E101', 'E102', 'E102', 'E103'],
        ['Alex', 'Alvin', 'Deniel', 'Jenny'],
        [21, 19, 15, 17]
    ]

# create a Multiindex using  from_arrays() 
mi = pd.MultiIndex.from_arrays(employees, names=('emp_id', 'name', 'age'))

# display the Multiindex
print("The MultiIndex...\n",mi)
print()

# Get the levels in MultiIndex
print("The levels in MultiIndex...\n",mi.levels)
print()

# Reorder levels 
print("Reorder levels (name, age, emp_id)...")
print(mi.reorder_levels(order=['name','age','emp_id']))
print()

# Reorder levels 
print("Reorder levels (emp_id, age, name)...")
print(mi.reorder_levels(order=['emp_id','age','name']))
print()

Output:

The MultiIndex...
 MultiIndex([('E101',   'Alex', 21),
            ('E102',  'Alvin', 19),
            ('E102', 'Deniel', 15),
            ('E103',  'Jenny', 17)],
           names=['emp_id', 'name', 'age'])

The levels in MultiIndex...
 [['E101', 'E102', 'E103'], ['Alex', 'Alvin', 'Deniel', 'Jenny'], [15, 17, 19, 21]]

Reorder levels (name, age, emp_id)...
MultiIndex([(  'Alex', 21, 'E101'),
            ( 'Alvin', 19, 'E102'),
            ('Deniel', 15, 'E102'),
            ( 'Jenny', 17, 'E103')],
           names=['name', 'age', 'emp_id'])

Reorder levels (emp_id, age, name)...
MultiIndex([('E101', 21,   'Alex'),
            ('E102', 19,  'Alvin'),
            ('E102', 15, 'Deniel'),
            ('E103', 17,  'Jenny')],
           names=['emp_id', 'age', 'name'])

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