If A and B are two sets. The set difference of A and B is a set of elements that exists only in set A but not in B.
To learn more, visit Python set difference.
The syntax of difference_update() is:
A.difference_update(B)
Here, A and B are two sets. The difference_update() updates set A with the set difference of A-B.
Return Value from difference_update()
The difference_update() returns None indicating the object (set) is mutated.
Suppose,
result = A.difference_update(B)
When you run the code,
- result will be
None - A will be equal to A-B
- B will be unchanged
Example: How difference_update() works?
A = {'a', 'c', 'g', 'd'}
B = {'c', 'f', 'g'}
result = A.difference_update(B)
print('A = ', A)
print('B = ', B)
print('result = ', result)
When you run the program, the output will be:
A = {'d', 'a'}
B = {'c', 'g', 'f'}
result = None