Method object is not subscriptable ошибка

В этой строке:

hero.coordinate = hero.step_forward

вы не вызываете метод, а записываете «ссылку» на метод в переменную. При следующей итерации цикла вы пытаетесь сделать hero.coordinate[0] по сути от ссылки на метод, о чем и говорится в ошибке. Вам просто нужно исправить данную строку на

hero.coordinate = hero.step_forward()

А вообще, по логике, метод .step_forward() должен менять координаты объекта, а не возвращать значение. Ваш код и меняет координаты объекта, и возвращает новое значение, которое вы потом еще раз записываете в поле с координатами объекта. Вам в принципе можно просто убрать return в методе step_forward() или никак не использовать значение, возвращенное из step_forward(). Вообще, лучше не менять вручную координаты объекта, обращаясь к ним снаружи, а делать это внутри методов.

Класс лучше реализовать так:

class Hero:
    def __init__(self, coordinate)
        # Если вы будете использовать один и тот же список с координатами для разных объектов, лучше при инициализации делать копию списка с помощью list
        self.coordinate = list(coordinate)

    def step_forward(self):
        self.coordinate[0] = self.coordinate[0] + 1

Тогда при создании объекта нужно будет еще указывать его координаты.

hero = Hero([0, 0])

enemy_hero = Hero([20, 0])

while True:

    distance = sqrt( (enemy_hero.coordinate[0] - hero.coordinate[0])**2 + (enemy_hero.coordinate[1] - hero.coordinate[1])**2)

    hero.step_forward()

distance тоже можно сделать методом того же класса:

class Hero:
    def __init__(self, coordinate)
        self.coordinate = list(coordinate)

    def step_forward(self):
        self.coordinate[0] = self.coordinate[0] + 1

    def distance(self, other):
        return sqrt( (other.coordinate[0] - self.coordinate[0])**2 + (other.coordinate[1] - self.coordinate[1])**2)

Тогда цикл будет выглядеть так:

while True:
    distance = hero.distance(enemy_hero)
    hero.step_forward()

When calling a method in Python, you have to use parentheses (). If you use square brackets [], you will raise the error “TypeError: ‘method’ object is not subscriptable”.

This tutorial will describe in detail what the error means. We will explore an example scenario that raises the error and learn how to solve it.

TypeError: ‘method’ object is not subscriptable

TypeErrror occurs when you attempt to perform an illegal operation for a particular data type. The part “‘method’ object is not subscriptable” tells us that method is not a subscriptable object. Subscriptable objects have a __getitem__ method, and we can use __getitem__ to retrieve individual items from a collection of objects contained by a subscriptable object. Examples of subscriptable objects are lists, dictionaries and tuples. We use square bracket syntax to access items in a subscriptable object. Because methods are not subscriptable, we cannot use square syntax to access the items in a method or call a method.

Methods are not the only non-subscriptable object. Other common “not subscriptable” errors are:

• “TypeError: ‘float’ object is not subscriptable“,
• “TypeError: ‘int’ object is not subscriptable“
• “TypeError: ‘builtin_function_or_method’ object is not subscriptable“
• “TypeError: ‘function’ object is not subscriptable“

Let’s look at an example of retrieving the first element of a list using the square bracket syntax

pizzas = ["margherita", "pepperoni", "four cheeses", "ham and pineapple"]
print(pizzas[0])

The code returns:

margherita

which is the pizza at index position 0. Let’s look at an example of calling a method using square brackets.

Example: Calling A Method With Square Brackets

Let’s create a program that stores fundamental particles as objects. The Particle class will tell us the mass of a particle and its charge. Let’s create a class for particles.

class Particle:

         def __init__(self, name, mass):

             self.name = name

             self.mass = mass

         def is_mass(self, compare_mass):

             if compare_mass != self.mass:

                 print(f'The {self.name} mass is not equal to {compare_mass} MeV, it is {self.mass} MeV')

             else:

                 print(f'The {self.name} mass is equal to {compare_mass} MeV')

The Particle class has two methods, one to define the structure of the Particle object and another to check if the mass of the particle is equal to a particular value. This class could be useful for someone studying Physics and particle masses for calculations.

Let’s create a muon object with the Particle class. The mass is in MeV and to one decimal place.

muon = Particle("muon", 105.7)

The muon variable is an object with the name muon and mass value 105.7. Let’s see what happens when we call the is_mass() method with square brackets and input a mass value.

muon.is_mass[105.7]

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [18], in <cell line: 1>()
----> 1 muon.is_mass[105.7]

TypeError: 'method' object is not subscriptable

We raise the TypeError because of the square brackets used to call the is_mass() method. The square brackets are only suitable for accessing items from a list, a subscriptable object. Methods are not subscriptable; we cannot use square brackets when calling this method.

Solution

We replace the square brackets with the round brackets ().

muon = Particle("muon", 105.7)

Let’s call the is_mass method with the correct brackets.

muon.is_mass(105.7)

muon.is_mass(0.51)

The muon mass is equal to 105.7 MeV

The muon mass is not equal to 0.51 MeV, it is 105.7 MeV

The code tells us the mass is equal to 105.7 MeV but is not equal to the mass of the electron 0.51 MeV.

To learn more about correct class object instantiation and calling methods in Python go to the article titled “How to Solve Python missing 1 required positional argument: ‘self’“.

Summary

Congratulations on reading to the end of this tutorial! The error “TypeError: ‘method’ object is not subscriptable” occurs when you use square brackets to call a method. Methods are not subscriptable objects and therefore cannot be accessed like a list with square brackets. To solve this error, replace the square brackets with the round brackets after the method’s name when you are calling it.

To learn more about Python for data science and machine learning, go to the online courses page on Python for the best courses available!

Have fun and happy researching!

Welcome to another module of TypeError in the python programming language. In today’s article, we will be discussing an embarrassing Typeerror that usually gets landed up while we are a beginner to python. The error is named as TypeError: ‘method’ object is not subscriptable Solution.

In this guide, we’ll go through the causes and ultimately the solutions for this TypeError problem.

What are Subscriptable Objects in Python?

Subscriptable objects are the objects in which you can use the [item] method using square brackets. For example, to index a list, you can use the list[1] way.

Inside the class, the __getitem__ method is used to overload the object to make them compatible for accessing elements. Currently, this method is already implemented in lists, dictionaries, and tuples. Most importantly, every time this method returns the respective elements from the list.

Now, the problem arises when objects with the __getitem__ method are not overloaded and you try to subscript the object. In such cases, the ‘method’ object is not subscriptable error arises.

Why do you get TypeError: ‘method’ object is not subscriptable Error in python?

In Python, some of the objects can be used to access the inside elements by using square brackets. For example in List, Tuple, and dictionaries. But what happens when you use square brackets to objects which arent supported? It’ll throw an error.

Let us consider the following code snippet:

names = ["Python", "Pool", "Latracal", "Google"]
print(names[0])

int("5")[0]

OUTPUT:- Python
TypeError: int object is not subscriptable

This code returns “Python,” the name at the index position 0. We cannot use square brackets to call a function or a method because functions and methods are not subscriptable objects.

Example Code for the TypeError

x = 3
x[0] # example 1

p = True
p[0] # example 2

max[2] # example 3

OUTPUT:-

Explanation of the code

1. Here we started by declaring a value x which stores an integer value 3.
2. Then we used [0] to subscript the value. But as integer doesn’t support it, an error is raised.
3. The same goes for example 2 where p is a boolean.
4. In example 3, max is a default inbuilt function which is not subscriptable.

The solution to the TypeError: method Object is not Subscriptable

The only solution for this problem is to avoid using square brackets on unsupported objects. Following example can demonstrate it –

x = 3
print(x)

p = True
print(p)

max([1])

OUTPUT:-

Our code works since we haven’t subscripted unsupported objects.

If you want to access the elements like string, you much convert the objects into a string first. The following example can help you to understand –

x = 3
str(x)[0] # example 1

p = True
str(p)[0] # example 2

Also, Read

FAQs

1. When do we get TypeError: ‘builtin_function_or_method’ object is not subscriptable?

Ans:- Let us look as the following code snippet first to understand this.

import numpy as np
a = np.array[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

OUTPUT:-

This problem is usually caused by missing the round parentheses in the np.array line.

It should have been written as:

a = np.array([1,2,3,4,5,6,7,8,9,10])

It is quite similar to TypeError: ‘method’ object is not subscriptable the only difference is that here we are using a library numpy so we get TypeError: ‘builtin_function_or_method’ object is not subscriptable.

Conclusion

The “TypeError: ‘method’ object is not subscriptable” error is raised when you use square brackets to call a method inside a class. To solve this error, make sure that you only call methods of a class using round brackets after the name of the method you want to call.

Now you’re ready to solve this common Python error like a professional coder! Till then keep pythoning Geeks!