Checking for non-common strings between two lists in Python

Question

Let's say that I have lists list_1=['a','b','c','d','e','f'] and list_2=['a','b','c','d']. I would like to know a method so that I can check automatically which strings are absent in list_2 but present in list_1. This is to be done on much longer lists.

Answer 1

You can use set.difference for the task:

list_1=['a','b','c','d','e','f']
list_2=['a','b','c','d']

print( set(list_1).difference(list_2) )

Prints:

{'e', 'f'}

Answer 2

answer = set(list_1) - set(list_2)

This should work for you

Answer 3

Once more method to get your desired output:

d=['a','b','c','d','e','f']
e=['a','b','c','d']
f=[]
for  i in d:
   if (i not in e):
       f.append(i)
print(f)

Answer 4

You could create your resulting set using a set comprehension:

result = {item for item in list_1 if item not in list_2}
print(result)
{'e', 'f'}