How to Call Methods in Python

Python is a popular programming language that is widely used for various applications, including web development, data analysis, machine learning, and artificial intelligence. In Python, methods are functions that are associated with an object or a class. They allow us to perform specific tasks, and they are an essential part of Python programming. In this article, we will learn how to call methods in Python and explore the different ways to do so.

Before we dive into the methods, we need to understand the object-oriented programming (OOP) paradigm in Python. In OOP, everything is an object, which means that we can create new objects, manipulate them and access their properties and methods. For example, if we want to work with a list of numbers, we can create a new list object, add numbers to it, and perform operations on it. Each list object has its unique properties and methods, such as sorting, reversing, or appending elements.

Creating and calling methods

To create a method in Python, we first need to define a class that contains the method. A class is a blueprint for creating objects, and it defines the properties and methods that the object will have. Here is an example of a class that defines a method:

class MyClass:
    def my_method(self):
        print("Hello, World!")

In this example, we define a class called MyClass that contains a method called my_method. The method takes one argument, self, which refers to the object that the method is called on. The method prints the string "Hello, World!" to the console.

To call the method, we first need to create an instance of the class. An instance is a specific object that is created from a class. Here is an example of creating an instance of MyClass and calling the my_method method:

my_object = MyClass()
my_object.my_method()

In this example, we create a new instance of MyClass called my_object. We then call the my_method method on the my_object instance. The output of this code will be "Hello, World!" printed to the console.

Calling built-in methods

Python has many built-in methods that are available for use without defining a new class. These methods are part of the Python standard library, and they can be used to perform common tasks, such as manipulating strings or lists. Here is an example of calling a built-in method:

my_string = "Hello, World!"
print(my_string.upper())

In this example, we create a string object called my_string that contains the text "Hello, World!". We then call the upper method on the my_string object. The upper method is a built-in method that returns a new string object with all characters in uppercase. The output of this code will be "HELLO, WORLD!" printed to the console.

Calling methods with arguments

Methods can take arguments, which are values that are passed to the method when it is called. The arguments can be used to modify the behavior of the method or to provide input data. Here is an example of a method that takes an argument:

class MyMath:
    def add(self, x, y):
        return x + y

my_math = MyMath()
result = my_math.add(2, 3)
print(result)

In this example, we define a class called MyMath that contains a method called add. The add method takes two arguments, x and y, and returns their sum. We then create an instance of MyMath called my_math and call the add method on it with the arguments 2 and 3. The output of this code will be 5 printed to the console.

Calling methods with default arguments

Methods can also have default arguments, which are values that are used if no value is provided for the argument when the method is called. Here is an example of a method with a default argument:

class MyPrinter:
    def print_message(self, message="Hello, World!"):
        print(message)

my_printer = MyPrinter()
my_printer.print_message()
my_printer.print_message("Python is awesome!")

In this example, we define a class called MyPrinter that contains a method called print_message. The print_message method takes one argument, message, which has a default value of "Hello, World!". The method prints the value of the message argument to the console. We then create an instance of MyPrinter called my_printer and call the print_message method twice. The first call has no argument, so the default value of "Hello, World!" is used. The second call specifies a custom message of "Python is awesome!". The output of this code will be "Hello, World!" and "Python is awesome!" printed to the console.

Calling methods with keyword arguments

Methods can also have keyword arguments, which are arguments that are passed to the method using their names. Keyword arguments are useful when a method has many arguments, and we want to specify only some of them. Here is an example of a method with keyword arguments:

class MyCalculator:
    def multiply(self, x, y, z=1):
        return x * y * z

my_calculator = MyCalculator()
result1 = my_calculator.multiply(2, 3, 4)
result2 = my_calculator.multiply(x=2, y=3, z=4)
result3 = my_calculator.multiply(y=3, x=2)
print(result1, result2, result3)

In this example, we define a class called MyCalculator that contains a method called multiply. The multiply method takes three arguments, x, y, and z, with z having a default value of 1. The method returns the product of the three arguments. We then create an instance of MyCalculator called my_calculator and call the multiply method three times with different combinations of arguments. The first call specifies all three arguments, the second call uses keyword arguments to specify all three arguments, and the third call uses keyword arguments to specify only two arguments but in a different order. The output of this code will be 24 24 6 printed to the console.

Calling methods with variable arguments

Methods can also have variable arguments, which are arguments that can accept a variable number of values. Variable arguments are useful when we don’t know how many arguments the method will receive or when we want to pass a list or tuple of values to the method. Here is an example of a method with variable arguments:

class MySum:
    def sum(self, *args):
        total = 0
        for number in args:
            total += number
        return total

my_sum = MySum()
result1 = my_sum.sum(2, 3, 4)
result2 = my_sum.sum(1, 2, 3, 4, 5)
result3 = my_sum.sum(*[1, 2, 3, 4, 5])
print(result1, result2, result3)

In this example, we define a class called MySum that contains a method called sum. The sum method takes a variable number of arguments using the args syntax. The method calculates the sum of all the arguments and returns the total. We then create an instance of MySum called my_sum and call the sum method three times with different numbers of arguments. The first call specifies three arguments, the second call specifies five arguments, and the third call uses the operator to unpack a list of five arguments. The output of this code will be 9 15 15 printed to the console.

Conclusion

In conclusion, methods are an essential part of Python programming, and they allow us to perform specific tasks on objects or classes. We can create methods by defining them in a class, or we can use built-in methods from the Python standard library. We can pass arguments to methods to modify their behavior or provide input data, and we can use default arguments, keyword arguments, or variable arguments to make our code more flexible and reusable. Knowing how to call methods in Python is a fundamental skill for any Python developer, and we hope that this article has helped you understand the different ways to do so.

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