Python | Difference between two lists

There are various ways in which the difference between two lists can be generated. In this article, we will see the different ways to Get the difference between two lists which can be done using Python.

Examples:  

Input:
list1 = [10, 15, 20, 25, 30, 35, 40]
list2 = [25, 40, 35] 

Output:
[10, 20, 30, 15]

Explanation:
resultant list = list1 - list2

 Note: When you have multiple same elements then this would not work. In that case, this code will simply remove the same elements.
In that case, you can maintain a count of each element in both lists.

Method 1: Use “in” to Find the Difference Between Two Lists in Python

In this example, we are using loop and Python in keyword to find the difference between two lists in Python.

Python3

li1 = [10, 15, 20, 25, 30, 35, 40]
li2 = [25, 40, 35]

temp3 = []
for element in li1:
    if element not in li2:
        temp3.append(element)

print(temp3)

Output:

[10, 15, 20, 30]

Method 2: Use set() to Find the Difference Between Two Lists in Python

Python3

li1 = [10, 15, 20, 25, 30, 35, 40]
li2 = [25, 40, 35]

s = set(li2)
temp3 = [x for x in li1 if x not in s]
print(temp3)

Output : 

[10, 15, 20, 30]

Method 3:  Use a list comprehension and set to Find the Difference Between Two Lists in Python

In this method, we convert the lists into sets explicitly and then simply reduce one from the other using the subtract operator. For more references on set visit Sets in Python. It is a similar technique that we used previously. The only difference is, that we replaced the nested loops with the list comprehension syntax.

Python3

li1 = [10, 15, 20, 25, 30, 35, 40]
li2 = [25, 40, 35]

s = set(li2)
temp3 = [x for x in li1 if x not in s]
print(temp3)

Output:

[10, 15, 20, 30]

Method 4: Without using the set()

In this method, we use the basic combination technique to copy elements from both lists with a regular check if one is present in the other or not. 

Python3

# Python code t get difference of two lists
# Not using set()
def Diff(li1, li2):
    li_dif = [i for i in li1 + li2 if i not in li1 or i not in li2]
    return li_dif

# Driver Code
li1 = [10, 15, 20, 25, 30, 35, 40]
li2 = [25, 40, 35]
li3 = Diff(li1, li2)
print(li3)

Output : 

[10, 15, 20, 30]

Method 5: Use Numpy to Find the Difference Between Two Lists in Python

The numpy.concatenate() function concatenate a sequence of arrays along an existing axis.

Python3

import numpy as np
li1 = np.array([10, 15, 20, 25, 30, 35, 40])
li2 = np.array([25, 40, 35])

dif1 = np.setdiff1d(li1, li2)
dif2 = np.setdiff1d(li2, li1)

temp3 = np.concatenate((dif1, dif2))
print(list(temp3))

Output:

[10, 15, 20, 30]

Method 6: Use symmetric_difference to Find the Difference Between Two Lists in Python

The elements that are either in the first set or the second set are returned using the symmetric_difference() technique. The intersection, unlike the shared items of the two sets, is not returned by this technique.

Python3

li1 = [10, 15, 20, 25, 30, 35, 40]
li2 = [25, 40, 35]

set_dif = set(li1).symmetric_difference(set(li2))
temp3 = list(set_dif)
print(temp3)

Output:

[20, 10, 30, 15]