Python Code Challenges: Lists (Advanced) - 5. Middle Item

[erikbjarum]

Hi,

I got stuck on the last assignement on the advanced part of lists.

I wrote the code with the correct functions, all though i tried to use floats in the even-number part.

However, I cannot wrap my head around the part for odd numbers. Let´s assume we have 7 elements in our list, i.e. len(str) is odd. Codecademy suggets we call str[int(len(str)/2)] which i do not understand, since len(str)/2 equals 3.5, but then we force it to become a integer which is resonable.

But if i create a variable i and set it equal to 3.5 then prints it, it will not be 4, as it prints 3.5 when i try it. Code example below. Then how does is manage to call for index 4 and be correct in the example above and fully copied below? Please advise!

i = 3.5
print(int(i))

Output: 3.5

Assignment: https://www.codecademy.com/courses/learn-python-3/articles/advanced-python-code-challenges-lists

#Write your function here
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]))

[toastedpitabread]

i = 3.5
print(int(i))

Should print 3 as it truncates the decimals (note: this is not the floor function). Are you sure this is printing 3.5?

[pluginmaybe]

Hi,
Remember arrays start at index 0, so the middle of an array of length 7 will be 3.
Not sure why you’re getting an output of 3.5
When I try it gives me 3.

[erikbjarum]

Hi,

Thanks!

Yes it´s correct as you say that the index starts at 0, however the len() function does not. Hence, if we have 7 indices for instance, the len() will be 7, i.e. len(str)/2 will return 3.5 which is not a valid index.

which should be the case using this function as they do:
"
else:
return lst[int(len(lst)/2)]
"

But as we do it with int, you say this should truncate it to three, which then would return the correct number?

Now as i try the int() function in print with i = 3.5 it seems to truncate correctly, might have been something wrong yesterday…

thanks!

[erikbjarum]

Must have been me who did something wrong yesterday while tired, worked perfectly today!

Thanks!