This article addresses the issue of encountering the error "TypeError: built_function_or_method object is not subscriptable" in Python and how to resolve it. While square brackets are commonly used to access subscriptable objects like lists, strings, dictionaries, and tuples in Python, this error occurs when attempting to use square brackets to access built-in methods or functions. Python indeed provides multiple solutions to this error, all of which will be explored in this guide.
Regarding the statement in the introduction about square brackets being the exclusive way to access subscriptable objects in Python, it's worth noting that there are exceptions to this rule. For instance, within a dictionary, one can access items using the dict.get(key)
method instead of square brackets. The following is the post's content:
Reason: To Call an Inbuilt Function or Method, Use Square Bracket
Solution: Instead of using square brackets, use parentheses.
An Alternative Approach: Access User-Defined Functions with Parentheses
Example: To pass a list as a function argument, enclose it in parenthesis.
Cause of Error: Subscripting a built-in function or method"
The primary cause of this Python program error is when a user attempts to use a built-in function or method with a square bracket. As far as we are aware, calling a function or method with a square bracket is not possible; instead, Python will produce the error "Not subscriptable" as seen below:
Code:
list_value=['python','and', 'linux' ]
list_value.pop[0]
print(list_value)
Output:
This error occurs when trying to use indexing or subscript notation on a built-in function or method in Python, which isn't supported.
When a square bracket is used in place of parentheses when calling the function, the reason snippet above displays a "TypeError."
Solution: Instead of using square brackets, use parentheses.
Make sure you call the built-in Python function or method using parentheses rather than square brackets to fix this error. The code block below displays the correct code:
Code:
list_value=['python','and', 'linux' ]
list_value.pop(0)
print(list_value)
Output:
The code above creates the list and uses the "list.pop()"
function to remove a specific item from the input list's index position "0"
What is "TypeError" in Python?
In Python, a TypeError is an error that occurs when an operation or function is applied to an object of an inappropriate type. It signifies that the data type being used is not compatible with the operation being performed. For instance, trying to add a string and an integer together might raise a TypeError because Python cannot directly perform arithmetic operations between these different data types.
The error message will typically provide details about the specific operation causing the issue and the types involved, helping developers identify and rectify the problem. Handling TypeErrors often involves checking and ensuring that the data types being used are compatible or converting them appropriately before the operation. Understanding TypeErrors is crucial for writing robust and error-free Python code.
What does the word TypeError means?
An Alternative Approach: Access User-Defined Functions with Parentheses
The prefix keyword "def"
in Python is used to define the user-defined function in the program. We store the user-defined function in a newly created object variable and call it using parentheses rather than square brackets. The code below displays an illustration of this solution:
Code:
def sample_list():
return ['python', 'ubuntu', 'linux']
list_1 = sample_list()
print(list_1)
Output:
In the above code, the user-defined function “sample_list”
is defined in the program. The function is accessed using parentheses. The return value of the function is kept in a variable named “list_1”
.
The function's returned value is successfully and error-free displayed on the output.
Example: To pass a list as a function argument, enclose it in parenthesis.
The function on the list is called using parenthesis in the example code provided below. To prevent an error, make sure a list is supplied to a function as an argument:
Code:
list_value = []
list_value.extend(['Python', 'Guide', 'Linux'])
print(list_value)
An empty list is created at program startup in the code above. The newly initialized list created inside the function's parentheses is called upon by the "list.extend()"
function.
Output:
The output above demonstrates that the function was successful in extending the list—a list that was supplied to the function as an argument—into an empty list.
Conclusion:
When a user tries to call a built-in function or method using a square bracket, they get the error "builtin_function_or_method' object is not subscriptable." To fix this error, access the built-in Python function or method by using parentheses rather than square brackets. Furthermore, a user-defined function whose solution is also given cannot be called using the brackets. This Python blog post explains several ways to deal with the error "builtin_function_or_method' object is not subscriptable."
References