Python Set difference() method

The python set difference() method is used to show the difference between two set elements as you learn in mathematics. First now understand,

How the Python difference() method works

Suppose we have the following two sets :

A = {1,2,3,4,5,6}
B = {1,2,3,8,7}

The difference between A and B is,
A-B = {4,5,6}

Firstly remove the common elements. Now, the element left in the first set is your answer. As we can see in the above example, In set A and B {1,2,3} are common so remove that. Now, the first set (A) is left with {4,5,6} element i.e our answer.

The difference between B and A is,
B-A = {8,7}

As we can see, in the python set A and B {1,2,3} elements are common so remove that. Now, the first set (B) is left with {8,7} element i.e our answer.

Note: A-B is equal to the elements present in A but not in B.
B-A is equal to the elements present in B but not in A.

Python difference() method Syntax :

Firstset.difference(second set) 

As per the above syntax, we can write as below.

A.difference(B) that means A-B
B.difference(A) that means B-A

Now, let’s understand with the help of examples.

Example 1:

A={12,3,4,6}

B={12,9,10,11}

print("A-B is",A.difference(B))

print("B-A is",B.difference(A))

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Output :

A-B is {3, 4, 6}
B-A is {9, 10, 11}

Example 2:

A={12,3,4,6}

B={12,9,10,11}

print(A-B)

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Output :

{3, 4, 6}

If all elements of the first set are present in the second set then it will return the null set (empty set).

Example 3:

A={12,4,6}

B={12,4,6,9,10,11}

print("A-B is" ,A-B)

print("B-A is", B-A)

Run Code >>

Output :

A-B is set()
B-A is {9, 10, 11}