In Python, functions are reusable blocks of code that perform a specific task. They help in structuring code and promoting reusability, making it easier to read and maintain.
Functions in Python
1. Basic Function Syntax
A function is defined using the def keyword, followed by the function name and parentheses () for parameters.
Example
def greet(name):
return "Hello, " + name
Explanation: The function greet takes a name parameter and returns a greeting message.
2. Lambda Functions
Lambda functions are small anonymous functions defined using the lambda keyword. They are useful for quick, single-use functions.
Example
double = lambda x: x * 2
print(double(5)) # Output: 10
Explanation: The lambda function takes an input x and returns x * 2.
3. Higher-Order Functions
Higher-order functions accept other functions as parameters or return functions. Functions like map, filter, and reduce are examples of higher-order functions in Python.
Using map
numbers = [1, 2, 3, 4]
squared = list(map(lambda x: x ** 2, numbers))
print(squared) # Output: [1, 4, 9, 16]
Explanation: map applies the lambda function to each item in the numbers list.
4. Decorators
Decorators allow you to modify the behavior of a function without changing its code. They are defined using the @ symbol above a function.
Example
def greet_decorator(func):
def wrapper():
print("Starting function:")
func()
print("Function completed.")
return wrapper
@greet_decorator
def say_hello():
print("Hello!")
say_hello()Explanation: The @greet_decorator applies the greet_decorator function to say_hello, modifying its behavior to print additional messages before and after the function call.
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