Python Set update() Method

The Set update() method adds elements from another set (or any other iterable) to the current set, without duplicates.

Syntax

my_set.update(set1, set2, ...)

update() Parameters

Python Set update() method parameters:

update() Return Value

Python Set update() method does not return any values: it modifies the set in place by adding elements from another set (or any other iterable), without duplicates.

Examples

Example 1: Update of Two Sets with update() method

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

A.update(B)

print(A) # Output: {'David', 'Ryan', 'Anna', 'Tom'}

output

{'David', 'Ryan', 'Anna', 'Tom'}

Example 2: Update between Multiple Sets

The update() method allows to adding elements from multiple sets, without duplicates:

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

A.update(B, C)

print(A) # Output: {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

output

{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

Example 3: Update between a Set and a List

You can also pass iterables like list: update() first converts the iterables to sets and then adds elements.

For example:

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

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

A.update(B)

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

output

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

Example 4: Update between a Set and a Tuple

You can also pass iterables like tuple: update() first converts the iterables to sets and then adds elements.

For example:

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

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

A.update(B)

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

output

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

Example 5: Update between a Set and a Dictionary

You can also pass iterables like dictionary: update() first converts the iterables to sets and then adds elements.

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.update(B)
A2.update(C)


print(A1) # Output: {1, 2, 3, 'a', 'e', 'o', 'i', 'u'}
print(A2) # Output: {'a', 'e', 'f', 'o', 'd', 'i', 'u'}

output

{1, 2, 3, 'a', 'e', 'o', 'i', 'u'}
{'a', 'e', 'f', 'o', 'd', 'i', 'u'}

Example 6: Update between a Set and a String

You can also pass iterables like string: update() first converts the iterables to sets and then adds elements.

For example:

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

B = 'def'

A.update(B)

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

output

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

Equivalent Operator |= for update()

Set Update can be performed with the |= operator as well, providing an alternative to the update() method.

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

A |= B

print(A) # Output: {1, 2, 3, 4, 5, 6, 7}

output

{1, 2, 3, 4, 5, 6, 7}

Moreover, you can use the |= operator with multiple sets:

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

A |= B | C

print(A) # Output: {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

output

{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}