[Tut] (Fixed) Python TypeError ‘bool’ object is not subscriptable

[Tut] (Fixed) Python TypeError ‘bool’ object is not subscriptable - Printable Version

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[Tut] (Fixed) Python TypeError ‘bool’ object is not subscriptable - xSicKxBot - 10-02-2022

(Fixed) Python TypeError ‘bool’ object is not subscriptable

5/5 – (1 vote)

[Image: image-11.png]

Problem Formulation

Consider the following minimal example where a

Code:
TypeError: 'bool' object is not subscriptable

occurs:

Code:
boo = True
boo[0]
# or:
boo[3:6]

This yields the following output:

Code:
Traceback (most recent call last): File "C:\Users\xcent\Desktop\code.py", line 2, in <module> boo[0]
TypeError: 'bool' object is not subscriptable

Solution Overview

Python raises the

Code:
TypeError: 'bool' object is not subscriptable

if you use indexing or slicing with the square bracket notation on a Boolean variable. However, the Boolean type is not indexable and you cannot slice it—it’s not iterable!

In other words, the Boolean class doesn’t define the

Code:
__getitem__()

method.

Code:
boo = True
boo[0] # Error!
boo[3:6] # Error!
boo[-1] # Error!
boo[:] # Error!

You can fix this error by

converting the Boolean to a string using the
Code:
str()
function because strings are subscriptable,
removing the indexing or slicing call,
defining a dummy
Code:
__getitem__()
method for a custom “Boolean wrapper class”.

Related Tutorials: Check out our tutorials on indexing and slicing on the Finxter blog to improve your skills!

Method 1: Convert Boolean to a String

If you want to access individual characters of the “Boolean” strings

Code:
"True"

and

Code:
"False"

, consider converting the Boolean to a string using the

Code:
str()

built-in function. A string is subscriptable so the error will not occur when trying to index or slice the converted string.

Code:
boo = True
boo_string = str(boo) print(boo_string[0])
# T
print(boo_string[1:-1])
# ru

Method 2: Put Boolean Into List

A simple way to resolve this error is to put the Boolean into a list that is subscriptable—that is you can use indexing or slicing on lists that define the

Code:
__getitem__()

magic method.

Code:
bools = [True, True, True, False, False, False, True, False]
print(bools[-1])
# False print(bools[3:-3])
# [False, False]

Method 3: Define the __getitem__() Magic Method

You can also define your own wrapper type around the Boolean variable that defines a dunder method for

Code:
__getitem__()

so that every indexing or slicing operation returns a specified value as defined in the dunder method.

Code:
class MyBool: def __init__(self, boo): self.boo = boo def __getitem__(self, index): return self.boo my_boolean = MyBool(True) print(my_boolean[0])
# True print(my_boolean[:-1])
# True

This hack is generally not recommended, I included it just for comprehensibility and to teach you something new.

Summary

The error message “

Code:
TypeError: 'boolean' object is not subscriptable

” happens if you access a boolean

Code:
boo

like a list such as

Code:
boo[0]

Code:
boo[1:4]

. To solve this error, avoid using slicing or indexing on a Boolean or use a subscriptable object such as lists or strings.