Function Arguments in Python

Last Updated on October 18, 2023 by Ankit Kochar

In Python, functions come in various forms, but at its core, a function can be defined as a code block designed to carry out a particular task. It accepts input arguments, if needed, executes the specified operation, and produces an output. Functions play a pivotal role in Python programming, enhancing code reusability and improving code legibility. They empower developers to execute code segments with predefined inputs, referred to as arguments. The use of arguments is indispensable for making functions adaptable and reusable. In this article, we will explore the concept of function arguments in Python.

What is a Function in Python?

In Python, a function is a self-contained block of code designed to accomplish a specific task. Functions are a fundamental programming concept that allows developers to promote code reusability by encapsulating distinct functionalities within a single, callable block. Functions are designed to accept inputs known as arguments, which grant them the flexibility to cater to various scenarios and adapt to different use cases.

What are Function Parameters in Python?

In Python, function parameters are the variables or placeholders specified in the function’s signature. These parameters act as receptacles for the values that will be supplied to the function when it is invoked.

Function parameters are used to specify the input requirements for a function. They allow the function to receive data from the calling code and use it to perform operations or calculations. Function parameters can be of any data type, including basic data types like integers, strings, and booleans, as well as more complex data types like lists, dictionaries, and objects.

In Python, function parameters can be assigned default values, which means that if an argument is not supplied when the function is called, the default value will be utilized instead. This feature is valuable for establishing optional parameters or defining a default behavior for a function.

What are Function Arguments in Python?

Function arguments in python are the inputs passed to a function to execute a specific task. Arguments are enclosed within parentheses, separated by commas, and can be of any data type. Arguments are used to make the function more versatile and adaptable. In Python, there are several types of function arguments in python, let’s understand them briefly here then we will see all of them with the example:

• Positional arguments: These are arguments that are passed to a function in the order they are defined in the function’s parameter list.
• Default arguments: These are arguments that have default values assigned to them in the function definition. The default value will be used in the case when the argument is not provided in the function.
• Keyword arguments: These are arguments that are passed to a function with the parameter name explicitly specified. This allows the arguments to be passed in any order, as long as the parameter name is specified.
• Variable-length arguments: These are arguments that allow a function to accept an arbitrary number of arguments. In Python, there are two types of variable-length arguments: *args, which accepts a variable number of positional arguments, and **kwargs, which accepts a variable number of keyword arguments.

Types of Function Arguments

In Python, there are mainly four types of function arguments:

1. Positional Arguments

Positional arguments are the most common type of arguments in Python functions. These arguments are passed to the function in a specific order based on their position. The order of the arguments is essential because the function interprets the arguments based on their position.

Here is an example of a function with positional arguments:

def add_numbers(a, b):
    return a + b

result = add_numbers(5, 10)
print(result)

Output

15

Explanation of the above code
In the above example, the function add_numbers() takes two positional arguments a and b. The arguments are passed in the order 5 and 10 respectively. The function that is explained in the above code returns the sum of the two numbers.

2. Keyword Arguments

Keyword arguments are passed to a function by explicitly specifying the parameter name and the argument value. These arguments are useful when we have many arguments, and we want to avoid confusion between the arguments’ positions.

Here is an example of a function with keyword arguments:

def student(name, age):
    print('Student Details:', name, age)

student('Naman', 21)

student(name='Vaibhav', age=22)

student('Vibhor', age=23)

Output

('Student Details:', 'Naman', 21)
('Student Details:', 'Vaibhav', 22)
('Student Details:', 'Vibhor', 23)

Explanation of the above code
In the above example, the function student() will print student names and ages with different types of argument passes.

3. Default Arguments

Default arguments are used when we want to provide a default value for an argument. If the value for an argument is not passed when calling the function, the default value is used instead.

Here is an example of a function with default arguments:

def exponent(base, power=2):
    return base ** power

print(exponent(5))
print(exponent(5, 3))

Output

25
125

Explanation of the above code
In the above example, the function exponent() takes two arguments base and power. The power argument has a default value of 2. When we call the function with only the base argument, the function uses the default value of 2 for the power argument.

4. Variable-Length Arguments

Variable-length arguments are used when we do not know the number of arguments that will be passed to the function. In Python, we can use two types of variable-length arguments:

• *4.1. args*
  When in a function we require to pass a variable of positional arguments we use the args syntax. The *args argument is treated as a tuple of arguments inside the function.

  • Python

  def my_function(*args):
      for arg in args:
          print(arg)
  
  my_function(1, 2, 3)
  

  Output

  1
  2
  3

  Explanation of the above code
  In the above example, we defined a function called my_function that takes a variable number of arguments using args. We then loop through the arguments and print each one. We can also pass multiple arguments to the function using args.

• 4.2 kwargs (Keyword Arguments)
  The kwargs syntax is used to pass a variable number of keyword arguments to a function. The kwargs argument is treated as a dictionary of key-value pairs inside the function. Here is an example of how to use kwargs:

  • Python

  def my_function(**kwargs):
      for key, value in kwargs.items():
          print(key, value)
  
  my_function(name="Vikas", age=20)
  

  Output

  ('age', 20)
  ('name', 'Vikas')

  Explanation of the above code
  In the above example, we defined a function called my_function that takes a variable number of keyword arguments using kwargs. We then loop through the arguments and print each key-value pair. We can also pass multiple keyword arguments to the function using kwargs.

Applications of Function Arguments in Python

Function arguments in python are a way to pass data to a function to perform some computation or operation on that data. Here are some common applications of function arguments:

• Customization of Function Behavior: Function arguments in python can be used to customize the behavior of a function. For example, a function that performs sorting can be customized to sort in ascending or descending order by passing an argument.
• Modularity: Function arguments in python can be used to create modular code, where different functions can be called with different arguments to perform different tasks.
• Reusability: Function arguments in python make it easier to reuse code. By passing different arguments to a function, the same function can be used in different parts of a program to perform different operations.
• Flexibility: Function arguments in python can be used to make a function more flexible. For example, a function that takes a variable number of arguments can be used to perform an operation on any number of inputs.
• Debugging: Function arguments in python can be used to help with debugging code. By passing different arguments to a function, the behavior of the function can be tested under different conditions, helping to identify potential bugs.

Conclusion
In Conclusion, function arguments in Python play a pivotal role in programming, enabling the creation of adaptable and reusable code. These arguments facilitate the reception of user input, empowering functions to execute intricate tasks and generate desired results. In this article, we examined various categories of function arguments in Python, encompassing default arguments, keyword arguments, variable-length arguments, and keyword-only arguments. Additionally, we delved into recommended practices for the effective utilization of function arguments, which involve employing descriptive names, adeptly addressing errors and exceptional scenarios, and thoroughly documenting the function’s functionality.

It is important to understand the different types of function arguments in python and when to use them to create efficient and readable code. Python’s flexibility with function arguments makes it an ideal programming language for a variety of use cases, from scientific computing to web development. With a strong understanding of function arguments, developers can create robust and scalable programs that meet the needs of their users.

Frequently Asked Questions related to Function Arguments in Python

Here are some of the FAQs related to Function Arguments in Python:

1. What is the purpose of using function arguments?
The primary purpose of using function arguments is to make functions versatile and adaptable. They enable functions to work with different input data and produce varied results.

2. How are function arguments defined in Python?
Function arguments are defined within the parentheses of a function’s definition. They can include parameters with default values, keyword arguments, variable-length arguments, and keyword-only arguments.

3. What are default arguments in Python?
Default arguments in Python are function parameters that have pre-assigned default values. If no argument is provided for these parameters when the function is called, the default values are used.

4. What are keyword arguments in Python?
Keyword arguments in Python allow you to pass arguments to a function using the parameter names as keywords. This approach enhances code readability and allows arguments to be provided in any order.

5. What are variable-length arguments (varargs) in Python?
Variable-length arguments, often denoted by an asterisk (*) in function definitions, allow functions to accept an arbitrary number of positional arguments. They are stored as a tuple within the function.

6. What are keyword-only arguments in Python?
Keyword-only arguments are function parameters that can only be passed using keyword syntax and cannot be provided as positional arguments. They are introduced using an asterisk (*) in the function definition.