[Tut] Python TypeError: NoneType is Not Subscriptable (Fix This Stupid Bug)

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Python TypeError: NoneType is Not Subscriptable (Fix This Stupid Bug)

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Do you encounter the following error message?

Code:

TypeError: NoneType is not subscriptable

You’re not alone! This short tutorial will show you why this error occurs, how to fix it, and how to never make the same mistake again.

So, let’s get started!

Summary

Python raises the

Code:

TypeError: NoneType is not subscriptable

if you try to index

Code:

x[i]

or slice

Code:

x[i:j]

a

Code:

None

value. The

Code:

None

type is not indexable, i.e., it doesn’t define the

Code:

__getitem__()

method. You can fix it by removing the indexing or slicing call, or defining the

Code:

__getitem__

method.

Example



The following minimal example that leads to the error:

Code:

x = None print(x[0]) # TypeError: 'NoneType' object is not subscriptable

You set the

Code:

variable

to the value

Code:

None

. The value

Code:

None

is not a container object, it doesn’t contain other objects. So, the code really doesn’t make any sense—which result do you expect from the indexing operation?

Exercise: Before I show you how to fix it, try to resolve the error yourself in the following interactive shell:

https://trinket.io/embed/python/e55b915062

If you struggle with indexing in Python, have a look at the following articles on the Finxter blog—especially the third!

Related Articles:

• Indexing in Python
  
  
• Slicing in Python
  
  
• Accessing the Index of Iterables in Python
  

Fixes

You can fix the non-subscriptable TypeError by wrapping the non-indexable values into a container data type such as a listin Python:

Code:

x = [None] print(x[0]) # None

The output now is the value

Code:

None

and the script doesn’t yield an error message anymore.

An alternative is to define the

Code:

__getitem__()

method in your code:

Code:

class X: def __getitem__(self, i): return f"Value {i}" variable = X() print(variable[0]) # Value 0

Related Tutorial: Python

Code:

__getitem__()

magic method

You overwrite the

Code:

__getitem__

method that takes one (index) argument

Code:

i

(in addition to the obligatory

Code:

self

argument) and returns the

Code:

i

-th value of the “container”.

In our case, we just return a string

Code:

"Value 0"

for the element

Code:

variable[0]

and

Code:

"Value 10"

for the element

Code:

variable[10]

.

Full Guide: Python Fixing This Subsctiptable Error (General)

What’s Next?

I hope you’d be able to fix the bug in your code! Before you go, check out our free Python cheat sheets that’ll teach you the basics in Python in minimal time: