Grab the pair of different items from two lists in Python

Question

I am trying to create a file with only the pairs of items that differ in two lists. I would like it to be position limited: L1 [0] != L2[0] --True (I want it!). L1 1 != L21 --False (I don't want it). However, my code is comparing each item from L1 with each item from L2 and returning undesired pairs.

l1 =  ["pear", "papaya", "guava"]
l2=   ["grape", "pear", "guava"]

The code

I just would like to have :

pear: grape
papaya: pear

Answer 1

If you can assume the length.. then you can simply take the index and compare equal indexes.

l1 =  ["pear", "papaya", "guava"]
l2=   ["grape", "pear", "guava"]

for index in range(len(l1)):
    if (l1[index] != l2[index]):
        print(f'{l1[index]}: {l2[index]}') 

Answer 2

Assuming the you lists have same length you can use the build-in function zip which return a generator of pairs.

l1 =  ["pear", "papaya", "guava"]
l2=   ["grape", "pear", "guava"]

print([f'{i}: {j}' for i, j in zip(l1, l2) if i != j])

If the length are different a combinatorics approach is suggested.