
Returning a function from a function means that a function is created and returned as output of another function. This is possible in Python because functions are first-class objects, which means they can be passed around just like any other object such as integers, strings, or lists.
Return function in Python
In next example, function1
returns a function function2
that multiplies its argument by a
. When function1(5)
is called, it returns function2
with a
set to 5
. This returned function is stored in the variable multiply_by_5
. We can then call multiply_by_5(3)
to get the result of 15
.
Example 1: Simple use of function return
def function1(a):
def function2(b):
return a * b
return function2
multiply_by_5 = function1(5)
result = multiply_by_5(3)
print(result) # Output: 15
Example 2: Add or multiply
def function3(operation):
def add_numbers(a, b):
return a + b
def multiply_numbers(a, b):
return a * b
if operation == "add":
return add_numbers
elif operation == "multiply":
return multiply_numbers
operation_type = "add"
math_function = function3(operation_type)
result = math_function(3, 5)
print(result) # Output: 8
In this example, function3
returns either the add_numbers
function or the multiply_numbers
function based on the value of the operation
parameter. If operation
is "add"
, the add_numbers
function is returned and if operation
is "multiply"
, the multiply_numbers
function is returned. The returned function is then stored in the math_function
variable. We can then call math_function(3, 5)
to add or multiply the two numbers based on the value of operation_type
. In this case, since operation_type
is "add"
, the output is 8
which is the sum of 3
and 5
.
Exploring the concept of nested functions and returning functions
In Python, functions can be nested, which means you can define one function inside another function. You can also return a function from another function. This concept of nested functions and returning functions allows for more flexibility and is a powerful tool in programming.
Example 1: Returning a function from a function
def create_adder(num):
def adder(x):
return num + x
return adder
add5 = create_adder(5)
print(add5(3)) # Output: 8
In this example, we define a function create_adder
that takes a parameter num
. Inside create_adder
, we define another function adder
that takes a parameter x
and returns the sum of num
and x
. Finally, create_adder
returns adder
.
We then create a new function add5
by calling create_adder(5)
. This means that add5
is now a reference to adder
with num
set to 5. When we call add5(3)
, we pass the parameter x
as 3
, which results in the output 8
.
Example 2: Nested functions
def outer_function(num):
def inner_function(x):
return num + x
return inner_function
add3 = outer_function(3)
add5 = outer_function(5)
print(add3(10)) # Output: 13
print(add5(10)) # Output: 15
In this example, we define a function outer_function
that takes a parameter num
. Inside outer_function
, we define another function inner_function
that takes a parameter x
and returns the sum of num
and x
. Finally, outer_function
returns inner_function
.
We then create two new functions add3
and add5
by calling outer_function(3)
and outer_function(5)
respectively. This means that add3
is now a reference to inner_function
with num
set to 3, and add5
is a reference to inner_function
with num
set to 5. When we call add3(10)
and add5(10)
, we pass the parameter x
as 10
, which results in the output 13
and 15
respectively.
Understanding the advantages of returning a function from another function
One of the significant benefits of returning a function from another function in Python is that it provides flexibility. By returning a function, the programmer can create a more specific and customized function based on the inputs passed to the original function. It also allows for efficient code reuse.
Another advantage of returning a function from another function is that it can simplify code complexity, leading to a more readable code structure. The code becomes more organized and understandable, thus enhancing its maintenance and debugging processes.
Here are two examples of returning a function from a function in Python:
Example 1: Returning a function that multiplies any number by a given factor:
def multiply(factor):
def inner(num):
return num * factor
return inner
double = multiply(2)
triple = multiply(3)
print(double(5)) #output: 10
print(triple(5)) #output: 15
By calling multiply(2)
and multiply(3)
, we create two new functions double
and triple
, respectively, that can be used to multiply any number by 2
or 3
.
Example 2: Returning a function that performs mathematical operations:
def operate(operation):
def inner(num1, num2):
if operation == 'add':
return num1 + num2
elif operation == 'subtract':
return num1 - num2
elif operation == 'multiply':
return num1 * num2
elif operation == 'divide':
return num1 / num2
return inner
add_func = operate('add')
subtract_func = operate('subtract')
print(add_func(10, 5)) #output: 15
print(subtract_func(10, 5)) #output: 5
By calling operate('add')
and operate('subtract')
, we create two new functions add_func
and subtract_func
, respectively, that can be used to perform addition and subtraction operations on any two numbers.
Understanding the different ways of defining and returning functions in Python
Returning a function from a function can be useful in situations where we need to create functions dynamically based on certain conditions.
def create_adder(num):
def adder(x):
return x + num
return adder
add5 = create_adder(5)
print(add5(10)) # Output: 15
In this example, we define a function called create_adder
that takes a num
parameter. Within the create_adder
function, we define another function called adder
that takes an x
parameter and returns the sum of num
and x
. Finally, we return the adder
function as an output.
We then assign the output of create_adder(5)
to a variable called add5
. This means that add5
is now a function that takes a parameter x
and returns the sum of 5
and x
. When we call add5(10)
, it returns 15
.
Exploring the use arguments in returned functions
def power(base):
def exponent(exp):
return base ** exp
return exponent
square = power(2)
cube = power(3)
print(square(5)) # Output: 25
print(cube(3)) # Output: 27
In this example, a nested function exponent
is defined inside the power
function. The exponent
function calculates a number raised to a power. The power
function returns the exponent
function. Two variables square
and cube
are assigned by calling the power
function with different base values. The final two print statements call square
and cube
with different exponent values.
def operation(operator):
def calculate(num1, num2):
if operator == '+':
return num1 + num2
elif operator == '-':
return num1 - num2
elif operator == '*':
return num1 * num2
elif operator == '/':
return num1 / num2
else:
return "Invalid operator"
return calculate
addition = operation('+')
subtraction = operation('-')
multiplication = operation('*')
division = operation('/')
print(addition(5, 3)) # Output: 8
print(subtraction(5, 3)) # Output: 2
print(multiplication(5, 3)) # Output: 15
print(division(5, 3)) # Output: 1.6666666666666667
print(operation('%')(5, 3)) # Output: Invalid operator
In this example, the operation
function takes an operator
parameter and returns the calculate
function. The calculate
function performs the arithmetic operation specified by the operator
parameter on two number arguments. Four variables addition
, subtraction
, multiplication
, and division
are assigned by calling the operation
function with different operator values. The final print statement shows what occurs when an invalid operator is used as an argument.
