比较不同长度的列表？

Question

I am comparing two different lists. I need to get the unique elements of each list (those not found in the other list).

Each new list contain what didn't exist in the other.

For example:

list1 = ['apple', 'coffee', 'orange', 'sugar']
list2 = ['apple', 'grape', 'orange', 'eggplant', 'pineapple']

Expected output

new_list1 = ['coffee', 'sugar']
new_list2 = ['grape', 'eggplant', 'pineapple']

Answer 1

The most straightforward way is to use sets

Example:

list1 = set(['apple', 'coffee', 'orange', 'sugar'])
list2 = set(['apple', 'grape', 'orange', 'eggplant', 'pineapple'])

new_list1 = list(list1 - list2)
new_list2 = list(list2 - list1)

Answer 2

If you just need the unique elements from each list and not have them in seperate lists use the XOR operator for sets and not difference:

list1 = ['apple', 'coffee', 'orange', 'sugar']
list2 = ['apple', 'grape', 'orange', 'eggplant', 'pineapple']

unique = set(list1) ^ set(list2)

Answer 3

You can optimize above solution like this:

>>> list(set(list1)-set(list2))
['coffee', 'sugar']
>>> list(set(list2)-set(list1))
['eggplant', 'grape', 'pineapple']

Answer 4

Simple looping example but not necessarily the most efficient:

new_list_1 = [item for item in list1 if item not in list2]
new_list_2 = [item for item in list2 if item not in list1]