Python - Check if the Pandas Index only consists of booleans

To check if a Pandas Index only consists of boolean values, use the is_boolean() method. This method returns True if all index values are boolean (True or False), otherwise False.

Syntax

index.is_boolean()

Return Value

Returns True if the index contains only boolean values, False otherwise.

Example with Boolean Index

Let's create an index with only boolean values and check using is_boolean() ?

import pandas as pd

# Creating Pandas index with boolean values
index = pd.Index([True, True, False, False, True, True, True])

# Display the Pandas index
print("Pandas Index...\n", index)

# Return the number of elements in the Index
print("\nNumber of elements in the index...\n", index.size)

# Return the dtype of the data
print("\nThe dtype object...\n", index.dtype)

# Check whether index values have only booleans
print("\nIndex values only consists of booleans?\n", index.is_boolean())

Pandas Index...
 Index([True, True, False, False, True, True, True], dtype='object')

Number of elements in the index...
7

The dtype object...
object

Index values only consists of booleans?
True

Example with Mixed Data Types

Now let's see what happens when the index contains non-boolean values ?

import pandas as pd

# Creating index with mixed data types
mixed_index = pd.Index([True, False, 1, 0, 'True'])

# Display the index
print("Mixed Index...\n", mixed_index)

# Check if it contains only booleans
print("\nIndex values only consists of booleans?\n", mixed_index.is_boolean())

# Creating index with integers
int_index = pd.Index([1, 0, 1, 0])
print("\nInteger Index...\n", int_index)
print("Index values only consists of booleans?\n", int_index.is_boolean())

Mixed Index...
 Index([True, False, 1, 0, 'True'], dtype='object')

Index values only consists of booleans?
False

Integer Index...
 Index([1, 0, 1, 0], dtype='int64')
Index values only consists of booleans?
False

Key Points

• The method only returns True for actual boolean values (True/False)
• Integer values like 1 and 0 are not considered boolean
• String representations like 'True' are not considered boolean
• The index dtype doesn't need to be 'bool' for this method to return True

Conclusion

The is_boolean() method provides a quick way to verify if a Pandas Index contains only boolean values. It strictly checks for True and False values, not their numeric or string equivalents.