two list find values

Question

should look something like this:

if items in both lists (equal/ larger/smaller):
   do something
else:
   if items in both lists (equal/ larger/smaller):
       do something
   else:
       do something

Answer 1

Well, it's unclear but seems like this is what you want:

list3 = [i for i in list2 if i not in list1]

Now:

print(list3)

Is:

[4]

If one element list, you care about, do:

print(next(iter(list3),list3))

Then output:

4

And if list3 is a list of more than 1 element for example:

[1,2]

This will still output:

[1,2]

Or ^ operator for sets (second part for slicing out first half of the list):

list3 = list(set(list2)^set(list1))
list3=list3[len(list3)//2:]

Now:

print(list3)

Is:

[4]

Then also can use next stuff for list3

Or can do symmetric_difference:

list3 = set.symmetric_difference(set(list1),set(list2))
list3=list(list3)[len(list3)//2:]

Now:

print(list3)

Is:

[4]

Can do same stuff for next

And as you want a while loop:

l=[i for i in list2 if i not in list1]
it=iter(l)
while l!=list3:
   list3.append(next(it))

A dummy way of doing this tho ...

And now:

print(list3)

Is:

[4]

And can do same next stuff

Or even better:

num = 0
while num < len(list2):
    if list2[num] != list1[num]:
        list3.append(list2[num])
    num += 1

And now:

print(list3)

Is:

[4]

And can do same next stuff