Python Set difference_update() Method

The Set difference_update() method finds the difference between two sets. It modifies the given set that contains all the elements of the first set that are not present in the second set.

Syntax

my_set.difference_update(set1, set2, ...)

difference_update() Parameters

Python Set difference_update() method parameters:

difference_update() Return Value

Python Set difference_update() method does not return any value: it modifies the original set in-place.

Examples

Example 1: Difference between Two Sets

A = {'Tom', 'Anna', 'David'}
B = {'David', 'Tom'}

A.difference_update(B)

print(A) # Output: {'Anna'}

output

{'Anna'}

Example 2: Difference between Multiple Sets

The difference_update() method allows to compute the difference between multiple sets:

A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
B = {3, 4, 5, 6, 7}
C = {6, 7, 8, 9, 10}

A.difference_update(B, C)

print(A) # Output: {1, 2}

output

{1, 2}

Example 3: Difference between a Set and a List

You can also pass iterables like list: difference_update() first converts the iterables to sets and then computes the difference in-place.

For example:

A = {'a', 'e', 'i', 'o', 'u'}

B = ['d', 'e', 'f']

A.difference_update(B)

print(A) # Output: {'i', 'a', 'o', 'u'}

output

{'i', 'a', 'o', 'u'}

Example 4: Difference between a Set and a Tuple

You can also pass iterables like tuple: difference_update() first converts the iterables to sets and then computes the difference in-place.

For example:

A = {'a', 'e', 'i', 'o', 'u'}

B = ('d', 'e', 'f')

A.difference_update(B)

print(A) # Output: {'i', 'a', 'o', 'u'}

output

{'i', 'a', 'o', 'u'}

Example 5: Difference between a Set and a Dictionary

You can also pass iterables like dictionary: difference_update() first converts the iterables to sets and then computes the difference in-place.

For example:

A1 = {'a', 'e', 'i', 'o', 'u'}
A2 = {'a', 'e', 'i', 'o', 'u'}

B = {1: 'd', 2: 'e', 3: 'f'}
C = {'d': 1, 'e': 2, 'f': 3}

A1.difference_update(B)
A2.difference_update(C)

print(A1) # Output: {'o', 'e', 'i', 'a', 'u'}
print(A2) # Output: {'o', 'a', 'u', 'i'}

output

{'o', 'e', 'i', 'a', 'u'}
{'o', 'a', 'u', 'i'}

Example 6: Difference between a Set and a String

You can also pass iterables like string: difference_update() first converts the iterables to sets and then computes the difference in-place.

For example:

A = {'a', 'e', 'i', 'o', 'u'}

B = 'def'

A.difference_update(B)

print(A) # Output: {'i', 'a', 'o', 'u'}

output

{'i', 'a', 'o', 'u'}

Equivalent Operator –= for difference_update()

Set difference can be performed with the -= operator as well, providing an alternative to the difference_update() method.

For example:

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

A -= B

print(A) # Output: {1, 2}

output

{1, 2}

Of course, you can use the -= operator with multiple sets:

A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
B = {3, 4, 5, 6, 7}
C = {6, 7, 8, 9, 10}

A -= B | C

print(A) # Output: {1, 2}

output

{1, 2}