Middle Item

[giosurguladze2525007]

Before this i understand much of things please can anyone explain me more about this. Thank you beforehand!

i have notebook where i am tying to write down everything what i have learnt and there is not nothing about int can, can anyone step by step explain me all!

def middle_element(lst):
  if len(lst) % 2 == 0:
    sum = lst[int(len(lst)/2)] + lst[int(len(lst)/2) - 1]
    return sum / 2
  else:
    return lst[int(len(lst)/2)]

#Uncomment the line below when your function is done
print(middle_element([5, 2, -10, -4, 4, 5]))

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[codeneutrino]

Welcome @giosurguladze2525007 to the forums! The int() function turns a string or a float into an integer. In python an integer is a number with no decimal point or speech marks(’’) around it. An integer in python would look like this:

this_is_an_integer = 1

I hope this helps!

[giosurguladze2525007]

Thank you very much!

can you explain my this calculation sum = lst[int(len(lst)/2)] + lst[int(len(lst)/2) - 1]
in the code

as i guess if len(lst) % 2 == 0 is (6/2=3 ==0) that is not correct yes
then is variable by sum and here i stuck

sum = lst[int(len(lst)/2)] + lst[int(len(lst)/2) - 1]

[codeneutrino]

This means the variable sum is equal to the item at the list index(point in the list) int(len(lst)/2) + the item of the list at the point lst[int(len(lst)/2) - 1].
In other words, you code finds two points in a list lst and adds them. You can tell this due to the square brackets [], which in Python denote the list index of a list.

Within those square brackets, is the list index.

The int() function makes sure the list index is not a decimal.

It then finds the length of the list lst, with the len() function, which returns a number.

It then divides that by two.

The second part, after the + sign does the same thing, except after it does the above calculation, it subtracts 1. Then, the code picks those two elements of the list, and adds them. Consider the code below:

lst = [1, 2, 3, 4, 5, 6, 7, 8]
variable1= lst[len(lst) / 2] #this would return 5, as that is the element of the list at the index 5.
#However, if the list was this:
lst = [1, 2, 3]
variable1 = lst[len(lst) / 2] #This would try to return the element of the list at 1.5, which does not exist. This is why you use the int() function. It makes sure the calculation lst[int(len(lst) / 2)] returns a  number that is not a decimal. In this case, it would return 3. 
#So, put it all together, in the following code:
lst = [1, 2, 3]
sum = lst[int(len(lst) / 2)] + lst[int(len(lst) / 2) - 1]
#What would this return?

I really hopes this helps! Sorry if I have worded it badly!

[codeneutrino]

P.S. In future, if you post code, to make it look fancy, click the button at the top of the post thing that looks like this: </>
Here is a screenshot:

When you click the button, it comes up with this:

Type over the text to get properly formatted code! I hope this helped as well!
Happy coding!

[codeneutrino]

If you use the int() function, you do not need the if...else statement. Sorry, I didn’t fully read your reply!

[giosurguladze2525007]

@tera5288723178

lst = [1, 2, 3, 4, 5, 6, 7, 8] variable1= lst[len(lst) / 2] #this would return 5, as that is the element of the list at the index 5. #However, if the list was this:

can you please tell me am i right ?
look in the lst there is 8 objects and and it would be 8 divided by 2 is 4 and why its 5 ?
sorry for but i am trying to catch a logic thank you very much again you made my day !

[codeneutrino]

It is five because the list index of 4 lst[4] returns the fifth item of the list, because list indexing starts from zero. i.e. lst=[1] 1 is at the zeroth place in the list.
In other words, to get lst=[1] to return 1, you would have to write return lst[0].

This means that the 5 in lst=[1, 2, 3, 4, 5, 6, 7, 8] is at the ‘fourth’ position.

(1 is at 0, 2 is at 1, 3 is at 2, 4 is at 3 and 5 is at 4.)
Consider the following code:

If you want, here is the link to the CodeCademy excercise on lists:
https://www.codecademy.com/courses/learn-python-3/lessons/use-python-list/exercises/operations-on-lists?action=resume_content_item
This interactive lesson covers all you need to know on list indexes.
Happy Coding!

[ionatan]

@tera5288723178

zeroth

actually, 0 is the first, not zeroth, and that makes 4 the fifth index

blame english.

this might make more sense if you used zoo animals instead of numbers as indices.

you wouldn’t say the tigerth value. you’d say third. and numbering them does not have the effect of re-ordering them, so it would remain the third, regardless of how you numbered them.

and 0 being the first makes plenty of sense, for example, what is the first amount of potatoes you have? zero, that’s what you have before you get one

[giosurguladze2525007]

you are right the count begins at 0 and

@tera5288723178

This means that the 5 in lst=[1, 2, 3, 4, 5, 6, 7, 8] is at the ‘fourth’ position.

it would be 9 objects

[giosurguladze2525007]

@giosurguladze2525007

def middle_element(lst): if len(lst) % 2 == 0: sum = lst[int(len(lst)/2)] + lst[int(len(lst)/2) - 1] return sum / 2 else: return lst[int(len(lst)/2)] #Uncomment the line below when your function is done print(middle_element([5, 2, -10, -4, 4, 5]))

sum = lst[int(len(lst)/2)] |||= 7 / 2 = 3.5 in python it is 4 ||| second st[int(len(lst)/2) - 1] = 7 / 2 = 3.5 - 1 is 2.5 that in python is 3 and total would be 7 its done with this okay next

@giosurguladze2525007

if len(lst) % 2 == 0:

len(lst) would be 7 / 2 is 3.5 and == is true but it does not true and way i get -7.0 ? this is confusing me

[codeneutrino]

You get 7.0 because when you use a modulo % operator, it returns a float(or a decimal number).

[ionatan]

>>> a = [1, 2, 3, 4, 5, 6, 7]
>>> len(a)
7
>>> type(len(a))
<class 'int'>
>>> len(a) % 2
1
>>> type(len(a) % 2)
<class 'int'>
>>> len(a) % 2 == 0
False

There should be no floats anywhere, everything here is done with integers (whole numbers)

For division, use //

>>> 7 // 2
3

there should be no conversions to int using int( ... ) because everything should already be and remain int

[codeneutrino]

If the length of the list lst is 7, the the code if len(lst) % 2 == 0 would return false because 7 divided by 2 gives a remainder of one. (7/2 = 3 remainder 1). Therefore your code would run the else code. I hope this helps!