Understanding Nested functions in python

Question

I am new in stackflow. I will so thankful if someone can help me.

I have to resolve this:

Define a nested function called nested_sum, where in the first part of the function you accept an argument called x, and in the second part (the function inside) you take another argument called y. In the function inside you have to calculate the sum of x and y.

To test your function create a variable called res_1 where you pass the x argument to nested_sum, and then create a variable called res_2 where you pass the y argument of the res_1 variable to get the final solution.

Have x equal 2 for res_1 and y equal 10 for res_2.

After looking on the internet I found a similar code, but I don't really understand how it works!

def nested_sum(x):
    def in_sum(y):
        return x+y
    return in_sum

res_1 = nested_sum(2)
res_2 = res_1(10)

Thank you

If you got your answer, please mark one as accepted clicking huge checkbox near it. — Alexander C
– Alexander C, Commented May 3, 2020 at 19:55

ruohola · Accepted Answer · 2020-05-01 16:58:52Z

4

First of all you need to realise res_1 is simply the in_sum() function.

Therefore as per your code:

nested_sum(2) puts x = 2 and then returns the in_sum() function. res_2 = res_1(10) = in_sum(10)

Therefore x = 2 and y = 10, so thus

x + y = 2 + 10 = 12

edited May 1, 2020 at 16:58

ruohola

24.8k7 gold badges76 silver badges118 bronze badges

answered May 1, 2020 at 16:36

Jackson

1,2031 gold badge6 silver badges14 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

user13439503 · Accepted Answer · 2020-05-01 17:04:18Z

0

You can write the code (easier to understand) as follows:

def nested_sum(x):
    def in_sum(y):
        return x+y
    return in_sum



res_1 = nested_sum(2) #nested_sum return in_sum(y) location with x=2 so --> res_1= in_sum (2+y)
res_2 = res_1(10)     #Cause res_1 points in_sum(2+y) res2=in_sum(2+10)=12

answered May 1, 2020 at 17:04

user13439503

1 Comment

Daniel Sanaguano Over a year ago

Thank so much. It is means that assigning a variable the result of a nested function the inner functions are methods of this variable?

Alexander C · Accepted Answer · 2020-05-01 17:07:20Z

0

First of all, function in Python is an object. Think of it as a piece of paper where it is written what arguments it needs an what to do with them.

nested_sum(2) creates a new piece of paper where it is writen: «take the 𝑦 argument, add 2 to and return it.»

nested_sum(𝑥) creates a new piece of paper where it is writen: «take the 𝑦 argument, add 𝑥 and return it.»

Let me rename variables in your code:

def increaser_function_maker(x):

    def the_new_function(y):
        return x + y

    return the_new_function

function_that_takes_number_and_adds_two_to_it = increaser_function_maker(2)
result = function_that_takes_number_and_adds_two_to_it(10)

There is another way to make this function. Maybe it will be easier to understand:

def increaser_function_maker(value_to_add):
    return lambda i: i + value_to_add

answered May 1, 2020 at 17:07

Alexander C

4,0752 gold badges26 silver badges42 bronze badges

1 Comment

Daniel Sanaguano Over a year ago

Thank you. I understand better from all answers.

Collectives™ on Stack Overflow

Understanding Nested functions in python

3 Answers 3

Comments

1 Comment

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related