Python Math - TypeError: nonetype object is not subscriptable

Question

I'm making a small program for math (no particular reason, just kind of wanted to) and I ran into the error "TypeError: 'NoneType' object is not subscribable.

I have never before seen this error, so I have no idea what it means.

import math 

print("The format you should consider:")

print str("value 1a")+str(" + ")+str("value 2")+str(" = ")+str("value 3a ")+str("value 4")+str("\n") 

print("Do not include the letters in the input, it automatically adds them") 

v1 = input("Value 1: ") 

v2 = input("Value 2: ")

v3 = input("Value 3: ") 

v4 = input("Value 4: ") 

lista = [v1, v3] 

lista = list.sort(lista) 

a = lista[1] - lista[0] 

list = [v2, v4] 

list = list.sort(list) 

b = list[1] = list[0] 

print str(a)+str("a")+str(" = ")+str(b)

The error:

Traceback (most recent call last): File "C:/Users/Nathan/Documents/Python/New thing", line 16, in <module> 

a = lista[1] - lista[0] 

TypeError: 'NoneType' object is not subscriptable

Answer 1

To get rid of the error you can use lista.sort()method:-

The .sort() method is in place, and returns None. If you want something not in-place, which returns a value, you could use

sorted_list = sorted(lista)

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Answer 2

In general, the error means that you attempted to index an object that doesn't have that functionality. You are trying to subscript an object which you think is a list or dict, but actually is None. NoneType is the type of the None object which represents a lack of value, for example, a function that does not explicitly return a value will return None. '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 .

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Comments

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