Typeerror nonetype object is not subscriptable python ошибка

You might have worked with list, tuple, and dictionary data structures, the list and dictionary being mutable while the tuple is immutable. They all can store values. And additionally, values are retrieved by indexing. However, there will be times when you might index a type that doesn’t support it. Moreover, it might face an error similar to the error TypeError: ‘NoneType’ object is not subscriptable.

list_example = [1, 2, 3, "random", "text", 5.64]
tuple_example = (1, 2, 3, "random", "text", 5.64)

print(list_example[4])
print(list_example[5])
print(tuple_example[0])
print(tuple_example[3])

What is a TypeError?

The TypeError occurs when you try to operate on a value that does not support that operation. The most common reason for an error in a Python program is when a certain statement is not in accordance with the prescribed usage. The Python interpreter immediately raises a type error when it encounters an error, usually along with an explanation.

Let’s reproduce the type error we are getting:

On trying to index the var variable, which is of NoneType, we get an error. The ‘NoneType’ object is not subscriptable.

Let’s break down the error we are getting. Subscript is another term for indexing. Likewise, subscriptable means an indexable item. For instance, a list, string, or tuple is subscriptable. None in python represents a lack of value for instance, when a function doesn’t explicitly return anything, it returns None. Since the NoneType object is not subscriptable or, in other words, indexable. Hence, the error ‘NoneType’ object is not subscriptable.

An object can only be subscriptable if its class has __getitem__ method implemented.

By using the dir function on the list, we can see its method and attributes. One of which is the __getitem__ method. Similarly, if you will check for tuple, strings, and dictionary, __getitem__ will be present.

However, if you try the same for None, there won’t be a __getitem__ method. Which is the reason for the type error.

Resolving the ‘NoneType’ object is not subscriptable

The ‘NoneType’ object is not subscriptable and generally occurs when we assign the return of built-in methods like sort(), append(), and reverse(). What is the common thing among them? They all don’t return anything. They perform in-place operations on a list. However, if we try to assign the result of these functions to a variable, then None will get stored in it. For instance, let’s look at their examples.

Example 1: sort()

list_example = [1, 11, 14, 10, 5, 3, 2, 15, 77]
list_example_sorted = list_example.sort()
print(list_example_sorted[0])

The sort() method sorts the list in ascending order. In the above code, list_example is sorted using the sort method and assigned to a new variable named list_example_sorted. On printing the 0th element, the ‘NoneType’ object is not subscriptable type error gets raised.

Recommended Reading | [Solved] TypeError: method Object is not Subscriptable

Example 2: append()

list_example = [1, 11, 14, 10, 5, 3, 2, 15, 77]
list_example_updated = list_example.append(88)
print(list_example_updated[5])

The append() method accepts a value. The value is appended to t. In the above code, the return value of the append is stored in the list_example_updated variable. On printing the 5th element, the ‘NoneType’ object is not subscriptable type error gets raised.

Example 2: reverse()

Similar to the above examples, the reverse method doesn’t return anything. However, assigning the result to a variable will raise an error. Because the value stored is of NoneType.

list_example = [1, 11, 14, 10, 5, 3, 2, 15, 77]
list_example_reversed = list_example.reverse()
print(list_example_reversed[5])

Recommended Reading | How to Solve TypeError: ‘int’ object is not Subscriptable

The solution to the ‘NoneType’ object is not subscriptable

It is important to realize that all three methods don’t return anything to resolve this error. This is why trying to store their result ends up being a NoneType. Therefore, avoid storing their result in a variable. Let’s see how we can do this, for instance:

Solution for sort() method

list_example = [1, 11, 14, 10, 5, 3, 2, 15, 77]
list_example.sort()
print(list_example[0])

Solution for append() method

list_example = [1, 11, 14, 10, 5, 3, 2, 15, 77]
list_example.append(88)
print(list_example[-1])

Solution for the reverse() method

list_example = [1, 11, 14, 10, 5, 3, 2, 15, 77]
list_example_reversed = list_example.reverse()
print(list_example_reversed[5])

TypeError: ‘NoneType’ object is not subscriptable, JSON/Django/Flask/Pandas/CV2

The error, NoneType object is not subscriptable, means that you were trying to subscript a NoneType object. This resulted in a type error. ‘NoneType’ object is not subscriptable is the one thrown by python when you use the square bracket notation object[key] where an object doesn’t define the __getitem__ method. Check your code for something of this sort.

None[something]

FAQs

Conclusion

This article covered TypeError: ‘NoneType’ object is not subscriptable. We talked about what is a type error, why the ‘NoneType’ object is not subscriptable, and how to resolve it.

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In Python, NoneType is the type for the None object, which is an object that indicates no value. Functions that do not return anything return None, for example, append() and sort(). You cannot retrieve items from a None value using the subscript operator [] like you can with a list or a tuple. If you try to use the subscript operator on a None value, you will raise the TypeError: NoneType object is not subscriptable.

To solve this error, ensure that when using a function that returns None, you do not assign its return value to a variable with the same name as a subscriptable object that you will use in the program.

This tutorial will go through the error in detail and how to solve it with code examples.

TypeError: ‘NoneType’ object is not subscriptable

Let’s break up the error message to understand what the error means. TypeError occurs whenever you attempt to use an illegal operation for a specific data type.

The subscript operator retrieves items from subscriptable objects. The operator in fact calls the __getitem__ method, for example a[i] is equivalent to a.__getitem__(i).

All subscriptable objects have a __getitem__ method. NoneType objects do not contain items and do not have a __getitem__ method. We can verify that None objects do not have the __getitem__ method by passing None to the dir() function:

print(dir(None))

['__bool__', '__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']

If we try to subscript a None value, we will raise the TypeError: ‘NoneType’ object is not subscriptable.

Example #1: Appending to a List

Let’s look at an example where we want to append an integer to a list of integers.

lst = [1, 2, 3, 4, 5, 6, 7]

lst = lst.append(8)

print(f'First element in list: {lst[0]}')

In the above code, we assign the result of the append call to the variable name lst. Let’s run the code to see what happens:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [1], in <cell line: 5>()
      1 lst = [1, 2, 3, 4, 5, 6, 7]
      3 lst = lst.append(8)
----> 5 print(f'First element in list: {lst[0]}')

TypeError: 'NoneType' object is not subscriptable

We throw the TypeError because we replaced the list with a None value. We can verify this by using the type() method.

lst = [1, 2, 3, 4, 5, 6, 7]

lst = lst.append(8)

print(type(lst))

<class 'NoneType'>

When we tried to get the first element in the list, we are trying to get the first element in the None object, which is not subscriptable.

Solution

Because append() is an in-place operation, we do not need to assign the result to a variable. Let’s look at the revised code:

lst = [1, 2, 3, 4, 5, 6, 7]

lst.append(8)

print(f'First element in list: {lst[0]}')

Let’s run the code to get the result:

First element in list: 1

We successfully retrieved the first item in the list after appending a value to it.

Example #2: Sorting a List

Let’s look at an example where we want to sort a list of integers.

numbers = [10, 1, 8, 3, 5, 4, 20, 0]

numbers = numbers.sort()

print(f'Largest number in list is {numbers[-1]}')

In the above code, we assign the result of the sort() call to the variable name numbers. Let’s run the code to see what happens:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [8], in <cell line: 3>()
      1 numbers = [10, 1, 8, 3, 5, 4, 20, 0]
      2 numbers = numbers.sort()
----> 3 print(f'Largest number in list is {numbers[-1]}')

TypeError: 'NoneType' object is not subscriptable

We throw the TypeError because we replaced the list numbers with a None value. We can verify this by using the type() method.

numbers = [10, 1, 8, 3, 5, 4, 20, 0]

numbers = numbers.sort()

print(type(numbers))

<class 'NoneType'>

When we tried to get the last element of the sorted list, we are trying to get the last element in the None object, which is not subscriptable.

Solution

Because sort() is an in-place operation, we do not need to assign the result to a variable. Let’s look at the revised code:

numbers = [10, 1, 8, 3, 5, 4, 20, 0]

numbers.sort()

print(f'Largest number in list is {numbers[-1]}')

Let’s run the code to get the result:

Largest number in list is 20

We successfully sorted the list and retrieved the last value of the list.

Summary

Congratulations on reading to the end of this tutorial! The TypeError: ‘NoneType’ object is not subscriptable occurs when you try to retrieve items from a None value using indexing. If you are using in-place operations like append, insert, and sort, you do not need to assign the result to a variable.

For further reading on TypeErrors, go to the articles:

• How to Solve Python TypeError: ‘function’ object is not subscriptable
• How to Solve Python TypeError: ‘bool’ object is not subscriptable

Go to the online courses page on Python to learn more about Python for data science and machine learning.

Have fun and happy researching!

Python objects with the value None cannot be accessed using indexing. This is because None values do not contain data with index numbers.

If you try to access an item from a None value using indexing, you encounter a “TypeError: ‘NoneType’ object is not subscriptable” error.

In this guide, we talk about what this error means and break down how it works. We walk through an example of this error so you can figure out how to solve it in your program.

TypeError: ‘NoneType’ object is not subscriptable

Subscriptable objects are values accessed using indexing. “Indexing” is another word to say “subscript”, which refers to working with individual parts of a larger collection.

For instance, lists, tuples, and dictionaries are all subscriptable objects. You can retrieve items from these objects using indexing. None values are not subscriptable because they are not part of any larger set of values.

The “TypeError: ‘NoneType’ object is not subscriptable” error is common if you assign the result of a built-in list method like sort(), reverse(), or append() to a variable. This is because these list methods change an existing list in-place. As a result, they return a None value.

An Example Scenario

Build an application that tracks information about a student’s test scores at school. We begin by defining a list of student test scores:

scores = [
	   { "name": "Tom", "score": 72, "grade": "B" },
	   { "name": "Lindsay", "score": 79, "grade": "A" }
]

Our list of student test scores contains two dictionaries. Next, we ask the user to insert information that should be added to the “scores” list:

name = input("Enter the name of the student: ")
score = input("Enter the test score the student earned: ")
grade = input("Enter the grade the student earned: ")

We track three pieces of data: the name of a student, their test score, and their test score represented as a letter grade.

Next, we append this information to our “scores” list. We do this by creating a dictionary which we will add to the list using the append() method:

new_scores = scores.append(
	{ "name": name, "score": score, "grade": grade }
)

This code adds a new record to the “scores” list. The result of the append() method is assigned to the variable “new_scores”.

Finally, print out the last item in our “new_scores” list so we can see if it worked:

The value -1 represents the last item in the list. Run our code and see what happens:

Enter the name of the student: Wendell
Enter the test score the student earned: 64
Enter the grade the student earned: C
Traceback (most recent call last):
  File "main.py", line 14, in <module>
	print(new_scores[-1])
TypeError: 'NoneType' object is not subscriptable

Our code returns an error.

The Solution

Our code successfully asks our user to insert information about a student. Our code then adds a record to the “new_scores” list. The problem is when we try to access an item from the “new_scores” list.

Our code does not work because append() returns None. This means we’re assigning a None value to “new_scores”. append() returns None because it adds an item to an existing list. The append() method does not create a new list.

To solve this error, we must remove the declaration of the “new_scores” variable and leave scores.append() on its own line:

scores.append(
	{ "name": name, "score": score, "grade": grade }
)
print(scores[-1])

We now only reference the “scores” variable. Let’s see what happens when we execute our program:

Enter the name of the student: Wendell
Enter the test score the student earned: 64
Enter the grade the student earned: C
{'name': 'Wendell', 'score': '64', 'grade': 'C'}

Our code runs successfully. First, our user is asked to insert information about a student’s test scores. Then, we add that information to the “scores” dictionary. Our code prints out the new dictionary value that has been added to our list so we know our code has worked.

Conclusion

The “TypeError: ‘NoneType’ object is not subscriptable” error is raised when you try to access items from a None value using indexing.

This is common if you use a built-in method to manipulate a list and assign the result of that method to a variable. Built-in methods return a None value which cannot be manipulated using the indexing syntax.

Now you’re ready to solve this common Python error like an expert.

1. the TypeError: 'NoneType' object is not subscriptable in Python
2. Solve the TypeError: 'NoneType' object is not subscriptable in Python
3. Conclusion

Python has various sequence data types like lists, tuples, and dictionaries that support indexing. Since the term subscript refers to the value used while indexing, these objects are also known as subscriptable objects.

In Python, incorrect indexing of such subscriptable objects often results in TypeError: 'NoneType' object is not subscriptable. In this article, we will discuss this error and the possible solutions to fix the same.

Ready? Let’s begin!

the TypeError: 'NoneType' object is not subscriptable in Python

Before we look at why the TypeError: 'NoneType' object is not subscriptable occurs and how to fix it, let us first get some basics out of the way.

Introduction to NoneType and Subscriptable Objects in Python

In Python, a NoneType object is an object that has no value. In other words, it is an object that does not return anything.

The value None is often returned by functions searching for something but not finding it. Below is an example where a function returns the None value.

def none_demo():
    for i in [1, 2, 3, 4, 5]:
        if i == 10:
            return yes

ans = none_demo()
print(ans)

Output:

Talking about subscriptable objects, as the name says, these are Python objects that can be subscripted or indexed. In simpler words, subscriptable objects are those objects that can be accessed or traversed with the help of index values like 0, 1, and so on.

Lists, tuples, and dictionaries are examples of such objects. Below is a code that shows how you can traverse a list with the help of indexing.

cakes = ['Mango', 'Vanilla', 'Chocolate']
for i in range(0,3):
    print(cakes[i])

Output:

Now you know the basics well, so let’s move forward!

Solve the TypeError: 'NoneType' object is not subscriptable in Python

In Python, there are some built-in functions like reverse(), sort(), and append() that we can use on subscriptable objects. But if we assign the results of these built-in functions to a variable, it results in the TypeError: 'NoneType' object is not subscriptable.

Look at the example given below. Here, we used the reverse() function on the list called desserts and stored the resultant in the variable ans.

Then, we printed the variable ans value, which turns out to be None as seen in the output. However, the last statement leads to the TypeError: 'NoneType' object is not subscriptable.

Any guesses why this happened?

desserts = ['cakes', 'pie', 'cookies']
ans = desserts.reverse()
print("The variable ans contains: ", ans)
print(ans[0])

Output:

The variable ans contains:  None
Traceback (most recent call last):
  File "<string>", line 4, in <module>
TypeError: 'NoneType' object is not subscriptable

This happened because, in the last line, we are subscripting the variable ans. We know that the variable ans contains the value None, which is not even a sequence data type; hence, it can’t be accessed by indexing.

The important thing to understand here is that although we are assigning the reversed list to the variable ans, that does not make that variable ans of a list type. Thus, we cannot access the variable ans using indexing, thinking of it as a list.

In reality, the variable ans is a NoneType object, and Python does not support indexing such objects. Thus, one must not try to index a non-subscriptable object, or it will lead to the TypeError: 'NoneType' object is not subscriptable.

To rectify this issue from the above code, follow the approach below.

This time we do not assign the result of the reverse() operation to any variable. That way, the function will automatically replace the current list with the reversed list without any extra space.

Later, we can print the list as we want. Here, we are first printing the entire reversed list and then accessing the first element using the subscript 0.

As you can see, the code runs fine and gives the desired output.

desserts = ['cakes', 'pie', 'cookies']
desserts.reverse()
print(desserts)
print(desserts[0])

Output:

['cookies', 'pie', 'cakes']
cookies

The same rule of not assigning the result to a variable and then indexing it applies to other functions like sort() and append() too. Below is an example that uses the sort() function and runs into the TypeError: 'NoneType' object is not subscriptable.

desserts = ['cakes', 'pie', 'cookies']
ans = desserts.sort()
print("The value of the variable is: ", ans)
print(ans[1])

Output:

The value of the variable is:  None
Traceback (most recent call last):
  File "<string>", line 4, in <module>
TypeError: 'NoneType' object is not subscriptable

Again, this happens for the same reason. We have to drop the use of another variable to store the sorted list to get rid of this error.

This is done below.

desserts = ['cakes', 'pie', 'cookies']
desserts.sort()
print(desserts)
print(desserts[1])

Output:

['cakes', 'cookies', 'pie']
cookies

You can see that, this time, the sort() method replaces the list with the new sorted list without needing any extra space. Later, we can access the individual elements of the sorted list using indexing without worrying about this error!

And here is something interesting. Ready to hear it?

In the case of the sort() function, if you still want to use a separate variable to store the sorted list, you can use the sorted() function. This is done below.

desserts = ['cakes', 'pie', 'cookies']
ans = sorted(desserts)
print(ans)
print(ans[0])

Output:

['cakes', 'cookies', 'pie']
cakes

You can see that this does not lead to any error because the sorted() function returns a sorted list, unlike the sort() method that sorts the list in place.

But unfortunately, we do not have such alternate functions for reverse() and append() methods.

This is it for this article. Refer to this documentation to know more about this topic.

Conclusion

This article taught us about the 'NoneType' object not subscriptable TypeError in Python. We saw how assigning the values of performing operations like reverse() and append() on sequence data types to variables leads to this error.

We also saw how we could fix this error by using the sorted() function instead of the sort() function to avoid getting this error in the first place.