Functions in Python

Welcome to my Blog, In this article you learn brief description of functions in python

Definition of function

A function is a block of code ,reusable code that is used to perform a action and python gives many built in function like print() but you can create a own function.Python Function take zero or more arguments and return a value. We create a function using the def keyword.

There are a three types of functions in Python:
  1. built-in : built-in functions,such as help(),max(),min(),print() and more of these functions click here
  2. User Defined Functions:
  3. Anonymous functions,which are also called lambda function because they are not started with def keyword.

2) User Defined Functions some examples here:

def hello():
	print("Hello World")
	return 
hello()

if you not pass any return value then function return an object None when call a function if return value is exist then function return a result see example below:

def hello():
	return "Hello World"
hello() #Hello World
  1. Function with Arguments:

Arguments are which are given to any function when function call.while the function refers to the arguments by their parameter names. There are four types of arguments:

a) Default arguments.
b) Required arguments.
c) Keyword arguments.
d) Variable number of arguments.

a) Default Arguments:

Default arguments those are take a default value if you no argument passed during the function call.you can define the default value with = operator.

def plus(a,b = 2):
  return a + b
plus(a=1)

b) Required arguments:

They are required arguments need to be passed when call an function.

def plus(a,b):
  return a + b
plus(15,10)

c) Keyword arguments:

You can use the keyword arguments in your function call. You use these to identify the arguments by their parameter name and example below:

def add(a,b):
  return a + b
# Call 'add()' function with keyword arguments
add(a=1, b=2)

d) Variable Number of Arguments:

When you do not know exact number of arguments that you want to pass to function in this case you can use *args keyword to get all parameters:

def add(*args):
  return sum(args)
add(1,4,5)

3) Anonymous Functions in Python:

some examples of Anonymous functions in python:

1)
double = lambda x: x*2
double(5)

2)
sum = lambda x, y: x + y;
sum(4,5)

3)
from functools import reduce
my_list = [1,2,3,4,5,6,7,8,9,10]

# Use lambda function with 'filter()'
filtered_list = list(filter(lambda x: (x*2 > 10), my_list))

# Use lambda function with 'map()'
mapped_list = list(map(lambda x: x*2, my_list))

# Use lambda function with 'reduce()'
reduced_list = reduce(lambda x, y: x+y, my_list)

print(filtered_list)
print(mapped_list)
print(reduced_list)

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