Typeerror type object is not subscriptable ошибка

Summary

The part of the code that says -> list[int] is a type annotation for the return type of the function. It is a special notation that can be used by third-party tools to do some basic static type-checking on the code. The only effect it has on the code, as far as Python itself is concerned, is to add some metadata to the function:

>>> def example() -> list[int]:
...     pass
... 
>>> 'return' in example.__annotations__
True

Python itself will not do any type checking.

Similarly, the : list[int] part is a type annotation for the nums parameter for twoSum.

Depending on the Python version, this specific annotation may not be accepted.

Python 3.9 and above

The error is not reproducible. -> list[int] declares that the function is intended to return a list that contains all integer values, and : list[int] declares that another such list should be passed in for nums. These hints allow third-party tools like MyPy to look for problems before the code is compiled or run.

Python 3.7 or 3.8

This annotation is not accepted as-is. There are two workarounds:

1. Use a __future__ import, to access the «postponed evaluation of annotations» behaviour described in PEP 563:

# At the top of the code, along with the other `import`s
from __future__ import annotations

1. Use the corresponding class defined in the standard library typing module:

# At the top of the code
from typing import List

# when annotating the function
def twoSum(self, nums: List[int], target: int) -> List[int]:

Note the capital L in List.

Python 3.5 and 3.6

The __future__ annotation is not supported. Use the typing module.

Python 3.4 and below

Type annotations are not supported at all. Simply remove them:

def twoSum(self, nums, target):

Again, remember that Python itself does not do anything meaningful with the annotations. They will not cause the code to raise exceptions for invalid parameters, convert them to the correct type, or anything else like that. They are only for third-party tools, and completely optional unless some other third-party tool is forcing their use.

Typeerror: type object is not subscriptable error occurs while accessing type object with index. Actually only those python objects which implements __getitems__() function are subscriptable. In this article, we will first see the root cause for this error. We will also explore how practically we can check which object is subscriptable and which is not. At last but not least, we will see some real scenarios where we get this error. So let’s start the journey.

Typeerror: type object is not subscriptable ( Fundamental Cause) –

The root cause for this type object is not subscriptable python error is invoking type object by indexing. Let’s understand with some practical scenarios.

var_list=[1,2,3]
var=type(var_list)
var[0]

Here var is a type python object. In the place of same, the list is python subscriptable object. Hence we can invoke it via index. Moreover, Here is the implementation –

var_list=[1,2,3]
var=type(var_list)
var_list[0]

The best way to fix this error is using correct object for indexing. Let’s understand with one example.

The fix is calling var[0] in the place of var_type[0] . Here ‘var’ is the correct object. It is a ‘str’ type object which is subscriptible python object.

How to check python object is subscriptable ?

Most importantly, As I explained clearly, Only those object which contains __getitems__() method in its object ( blueprint of its class) is subscriptible. Let’s see any subscriptible object and its internal method-

print(dir(var))

The output is –

['__add__', '__class__', '__contains__', '__delattr__', '__dir__',
 '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__',
 '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', 
'__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', 
'__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'capitalize', 'casefold',
 'center', 'count', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'format_map', 'index', 
'isalnum', 'isalpha', 'isascii', 'isdecimal', 'isdigit', 'isidentifier', 'islower', 'isnumeric', 
'isprintable', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'maketrans',
 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 
'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

Firstly, As the internal method __getitem__() is available in the implementation of the object of var( list) hence it is subscriptible and that is why we are not getting any error while invoking the object with indexes. Hope this article is helpful for your doubt.

Similar Errors-

Typeerror int object is not subscriptable : Step By Step Fix

Typeerror nonetype object is not subscriptable : How to Fix ?

Thanks

Data Science Learner Team

“type” is a special keyword in Python that denotes a value whose type is a data type. If you try to access a value from an object whose data type is “type”, you’ll encounter the “TypeError: ‘type’ object is not subscriptable” error.

This guide discusses what this error means and why you may see it. It walks you through an example of this error so you can learn how to fix the error whenever it comes up.

TypeError: ‘type’ object is not subscriptable

Python supports a range of data types. These data types are used to store values with different attributes. The integer data type, for instance, stores whole numbers. The string data type represents an individual or set of characters.

Each data type has a “type” object. This object lets you convert values to a particular data type, or create a new value with a particular data type. These “type” objects include:

• int()
• str()
• tuple()
• dict()

If you check the “type” of these variables, you’ll see they are “type” objects:

The result of this code is: “type”.

We cannot access values from a “type” object because they do not store any values. They are a reference for a particular type of data.

An Example Scenario

Build a program that displays information about a purchase made at a computer hardware store so that a receipt can be printed out. Start by defining a list with information about a purchase:

purchase = type(["Steelseries", "Rival 600 Gaming Mouse", 69.99, True])

The values in this list represent, in order:

• The brand of the item a customer has purchased
• The name of the item
• The price of the item
• Whether the customer is a member of the store’s loyalty card program

Next, use print() statements to display information about this purchase to the console:

print("Brand: " + purchase[0])
print("Product Name: " + purchase[1])
print("Price: $" + str(purchase[2]))

You print the brand, product name, and price values to the console. You have added labels to these values so that it is easy for the user to tell what each value represents.

Convert purchase[2] to a string using str() because this value is stored as a floating point number and you can only concatenate strings to other strings.

Next, check to see if a user is a member of the store’s loyalty card program. You do this because if a customer is not a member then they should be asked if they would like to join the loyalty card program:

if purchase[3] == False:
	    print("Would you like to join our loyalty card program?")
else:
	    print("Thanks for being a member of our loyalty card program. You have earned 10 points for making a purchase at our store.")

If a user is not a member of the loyalty card program, the “if” statement runs. Otherwise, the else statement runs and the user is thanked for making a purchase.

Run our code and see if it works:

Traceback (most recent call last):
  File "main.py", line 3, in <module>
	     print("Brand: " + purchase[0])
TypeError: 'type' object is not subscriptable

Our code returns an error.

The Solution

Take a look at the offending line of code:

print("Brand: " + purchase[0])

The “subscriptable” message says you are trying to access a value using indexing from an object as if it were a sequence object, like a string, a list, or a tuple. In the code, you’re trying to access a value using indexing from a “type” object. This is not allowed.

This error has occurred because you’ve defined the “purchase” list as a type object instead of as a list. To solve this error, remove the “type” from around our list:

purchase = ["Steelseries", "Rival 600 Gaming Mouse", 69.99, True]

There is no need to use “type” to declare a list. You only need to use “type” to check the value of an object. Run our code and see what happens:

Brand: Steelseries
Product Name: Rival 600 Gaming Mouse
Price: $69.99
Thanks for being a member of our loyalty card program. You have earned 10 points for making a purchase at our store.

The code prints out the information about the purchase. It also informs that the customer is a loyalty card member and so they have earned points for making a purchase at the store.

Conclusion

The “TypeError: ‘type’ object is not subscriptable” error is raised when you try to access an object using indexing whose data type is “type”. To solve this error, ensure you only try to access iterable objects, like tuples and strings, using indexing.

Now you’re ready to solve this error like a Python expert!

Уффф. Тут уже речь про основы синтаксиса питона.
Ваш первый код делает следующее.

num = list( #построить список из последовательности
    map( #вызываем функцию map()
        int, #первый параметр
        f.read().split() #второй параметр
    )
)

А второй код делает (точнее пытается) вот что

num = list( #построить список из последовательности
    map[ #обращаемся к объекту map и пытаемся получить значение по ключу
        int, #первый элемент кортежа-ключа
        f.read().split() #второй элемент кортежа-ключа
    ]
)

Так как map не является словарём или подобной коллекцией, то конечно это не работает, и генерирует именно такую ошибку, которую вы указали.
Я не пойму, откуда вообще взялась идея что можно просто заменить в вызове функции круглые скобки на квадратные, если у них совершенно разная семантика.
Ну и да, не может быть ничего кроме списка на выходе, так как результат работы map() (а это будет объект-генератор) явно преобразуется в список.
В общем, выше правильно посоветовали — почитайте учебник, того же Марка Лутца, «Изучаем Питон», хотя бы 4е издание. По-крайней мере такие ошибки отпадут.