#### A complete guide to mathematical set operations in Python

### Mathematical Set Operations in Python

Python’s `set`

is an unordered collection in Python. It can be used to compute standard math operations, such as intersection, union, difference, and symmetric difference. `Other`

collections — like list, tuple, and dictionary — don’t support set operations. `Dict`

view objects are set-like, which allows set operations. Refer to my story on Python sets.

This article will explore the mathematical operations supported by set objects in detail.

**Let’s Look at the Mathematical Operations Supported by the Set Object**

`union()`

`update()`

`intersection()`

`intersection_update()`

`difference()`

`difference_update()`

`symmetric_difference()`

`symmetric_difference_update()`

`isdisjoint()`

`issubset()`

`issuperset()`

Set operations can be done in two ways. By using the method or by using an operator.

**‘union()’**

Return a new set with elements from the set and the `other`

. It’s performed by `union()`

or by using the `|`

operator

**Syntax**

**union**(**others*)

**set | other | ...**

**Example 1: Find the union of two sets — ****A**** and ****B**

It’ll return a new set containing elements from set `A`

and set `B`

. But it won’t repeat elements. All elements in the set are unique.

A={1,2,3,4,5} B={2,4,6,8} print (A.union(B))#Output:{1, 2, 3, 4, 5, 6, 8} print (A|B)#Output:{1, 2, 3, 4, 5, 6, 8}

**Example 2: Find the union of more than two sets**

A={1,2,3,4,5} B={2,4,6,8,10} C={1,3,5,7,9} print (A|B|C)#Output:{1, 2, 3, 4, 5, 6, 7, 8, 9, 10} print (A.union(B,C))#Output:{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

Difference between the `union()`

method and the `|`

operator:

`union()`

: It’ll accept any iterable as an argument`|`

operator: It’ll accept only a set as an argument. Otherwise, it’ll raise a`TypeError`

.

**Example 3: Giving ****iterable**** as an argument in the ****union()**** method**

A={1,2,3,4,5} #iterable is given as list print (A.union([2,4,6]))#Output:{1, 2, 3, 4, 5, 6} #iterable is given as tuple print (A.union((2,4,6)))#Output:{1, 2, 3, 4, 5, 6} #iterable is given as range object print (A.union(range(5,10)))#Output:{1, 2, 3, 4, 5, 6, 7, 8, 9} #iterable is given as a dictionary print (A.union({'a':6,'b':7}))#Output:{1, 2, 3, 4, 5, 'b', 'a'}

**Example 4: Giving ****iterable**** as an argument for the****|**** operator**

A={1,2,3,4,5} B=[1,2,3] print (A|B)#Output:TypeError: unsupported operand type(s) for |: 'set' and 'list'

#### ‘update()’

It updates the set, adding elements from the `other`

. But it won’t repeat elements. All elements in the set are unique. It’s performed by using `update() `

or by using the `|=`

operator. The return type is `None`

. It’ll modify the original set itself.

**Syntax**

**update**(**others*)

**set |= other | ...**

**Example 1: Calling ****update()**** between two sets — ****A**** and ****B**

It’ll update set `A`

by adding elements found in both sets.

#update()A={1,2,3,4,5} B={4,5,6,7,8} print (A.update(B))#Output: Noneprint (A)#Output: {1, 2, 3, 4, 5, 6, 7, 8}

A={1,2,3,4,5} B={4,5,6,7,8} A|=B print (A)#Output: {1, 2, 3, 4, 5, 6, 7, 8}

**Example 2: Calling ****update()**** between more than two sets**

#update()A={1,2,3} B={3,4,5} C={5,6,7} print (A.update(B,C))#Output: Noneprint (A)#Output: {1, 2, 3, 4, 5, 6, 7}A={1,2,3} B={3,4,5} C={5,6,7} A|=B|C print (A)#Output: {1, 2, 3, 4, 5, 6, 7}

Difference between the `update()`

method and the `|=`

operator:

`update()`

: It’ll accept any iterable as an argument`|=`

operator: It’ll accept only a set as an argument. Otherwise, it’ll raise a`TypeError`

.

**Example 3: Giving ****iterable**** as an argument in the ****update()**** method**

A={1,2,3}#iterable is given as listprint (A.update([2,3,4]))#Output:Noneprint (A)#Output:{1,2,3,4} #iterable is given as tupleA={1,2,3} A.update((2,3,4)) print (A)#Output:{1,2,3,4} #iterable is given as range objectA={1,2,3} A.update(range(2,5)) print (A)#Output:{1,2,3,4} #iterable is given as a dictionaryA={1,2,3} A.update({2:'a',3:'b'}) print (A)#Output:{1, 2, 3}

**Example 4: Giving ****iterable**** as an argument for the ****|=**** operator**

#iterable is given as tupleA={1,2,3} B=(3,4) A|=B#Output:TypeError: unsupported operand type(s) for |=: 'set' and 'tuple'

#### ‘intersection()’

Return a new set with elements common to the set and the `other`

. It’s performed by `intersection()`

or by using the `&`

operator.

**Syntax**

**intersection**(**others*)

**set & other & ...**

**Example 1: Find the intersection of two sets — ****A**** and ****B**

It’ll return a new set containing common elements from the set `A`

and set `B`

.

A={1,2,3,4,5} B={2,4,6,8}#intersection is performed by intersection() method or & operatorprint (A.intersection(B))#Output:{2,4}print (A&B)#Output:{2,4}

**Example 2: Find the intersection of more than two sets**

A={1,2,3,4,5} B={2,4,6,8,10} C={2,4} print (A&B&C)#Output:{2,4}print (A.intersection(B,C))#Output:{2,4}

Difference between the `intersection()`

method and the `&`

operator:

`intersection()`

: It’ll accept any iterable as an argument`&`

operator: It’ll accept only a set as an argument. Otherwise, it’ll raise a`TypeError`

.

**Example 3: Giving ****iterable**** as an argument in the ****intersection()**** method**

A={1,2,3,4,5}#iterable is given as listprint (A.intersection([1,4,6]))#Output:{1,4} #iterable is given as tupleprint (A.intersection((2,4,6)))#Output:{2,4} #iterable is given as range objectprint (A.intersection(range(5,10)))#Output:{5} #iterable is given as a dictionaryprint (A.intersection({1:'a','b':7}))#Output:{1}

**Example 4: Giving ****iterable**** as an argument for the ****&**** operator**

A={1,2,3,4,5} B=[1,2,3] print (A&B)#Output:TypeError: unsupported operand type(s) for &: 'set' and 'list'

#### ’intersection_update()’

It updates the set, keeping only elements found in it and the `other`

. It’s performed by using` intersection_update()`

or by using the`&=`

operator. The return type is `None`

. It’ll modify the original set itself.

**Syntax**

**intersection_update**(**others*)

**set &= other & …**

**Example 1: Find the ****intersection_update()**** between two sets — ****A**** and ****B**

It’ll update set `A`

by keeping only the elements found in both of the sets.

#intersection_update()A={1,2,3,4,5} B={4,5,6,7,8} print (A.intersection_update(B))#Output: Noneprint (A)#Output: {4,5}

A={1,2,3,4,5} B={4,5,6,7,8} A&=B print (A)#Output: {4,5}

#### ‘difference()’

Returns a new set with elements in the set that aren’t in the `other`

. It’s performed by `difference()`

or by using the `-`

operator.

**Syntax**

**difference**(**others*)

**set - other - ...**

**Example 1: Find the difference between two sets — ****A**** and ****B**

It’ll return a new set containing elements from set `A`

not in set B.

A={1,2,3,4,5} B={2,4,6,8} print (A.difference(B))#Output:{1,3,5}print (A-B)#Output:{1,3,5}

**Example 2: Find the difference between more than two sets**

A={1,2,3,4,5} B={2,4,6,8,10} C={2,3} print (A-B-C)#Output:{1,5}print (A.difference(B,C))#Output:{1,5}

Difference between the `difference()`

method and the `-`

operator:

`difference()`

: It’ll accept any iterable as an argument`-`

operator: It’ll accept only a set as an argument. Otherwise, it’ll raise a`TypeError`

.

**Example 3: Giving ****iterable**** as an argument in the ****difference()**** method**

A={1,2,3,4,5}#iterable is given as listprint (A.difference([1,2,3]))#Output:{4,5} #iterable is given as tupleprint (A.difference((1,2,3)))#Output:{4,5} #iterable is given as range objectprint (A.difference(range(1,4)))#Output:{4,5} #iterable is given as a dictionaryprint (A.difference({1:'a',2:'b',3:'c'}))#Output:{4,5}

**Example 4: Giving ****iterable**** as an argument for the ****-**** operator**

A={1,2,3,4,5} B=[1,2,3] print (A-B)#Output:TypeError: unsupported operand type(s) for -: 'set' and 'list'

#### ‘difference_update()’

Removes the element from the set that’s also present in the `other`

set. It’s performed by using the `-= `

operator or by using the `difference_update() `

method. The return type is `None`

. It’ll modify the original set itself.

**Syntax**

**difference_update**(**others*)

**set -= other | ...**

**Example 1: Find the ****difference_update()**** between two sets — ****A**** and ****B**

It’ll update set `A`

by removing elements that are also present in set `B`

.

A={1,2,3,4,5} B={2,4,6}#Return type is None.print (A.difference_update(B))#Output:None #It will update the original setprint (A)#Output: {1,3,5} # difference_update by using -= operatorA-=(B) print (A)#Output: {1,3,5}

**Example 2: Find the ****difference_update**** between more than two sets**

#difference_update() will modify the original set.A={1,2,3} B={1} C={2}#Return type is None.print (A.difference_update(B,C))#Output:None #It will update the original setprint (A)#Output: {3} # difference_update by using -= operatorA={1,2,3} B={1} C={2} A-=B|C print (A)#Output: {3}

Difference between the `difference_update()`

method and the` -=`

operator:

`difference_update()`

: It’ll accept any iterable as an argument`-= operator`

: It’ll accept only a set as an argument. Otherwise, it’ll raise a`TypeError`

.

**Example 3: Giving ****iterable**** as an argument in the ****difference_update()**** method**

#iterable is given as listA={1,2,3} B=[1] print (A.difference_update(B))#Output:Noneprint (A)#Output:{2,3}

**Example 4: Giving ****iterable**** as an argument for ****-=****operator**

A={1,2,3} B=[1] A-=B print (A)#Output: TypeError: unsupported operand type(s) for -=: 'set' and 'list'

#### ‘symmetric_difference()’

Return a new set with elements in either the set or `other`

but not both. It’s performed by `symmetric_difference()`

or by using the `^`

operator.

**Syntax**

**symmetric_difference**(*other*)

**set ^ other**

**Example 1: Find the ****symmetric_difference**** between two sets — ****A**** and ****B**

It’ll return a new set containing elements from either set `A`

and set `B`

but not elements found in both sets.

A={1,2} B={2,3} print (A.symmetric_difference(B))#Output:{1,3}print (A^B)#Output:{1,3}

**Example 2: ****symmetric_difference**** is only performed between two sets**

The `symmetric_difference() method`

isn’t supported by multiple sets. If more than two sets are given, it’ll raise a `TypeError`

.

A={1,2} B={2,3,5} C={3,4} print (A.symmetric_difference(B,C))#Output:TypeError: symmetric_difference() takes exactly one argument (2 given)

But we can find the `symmetric_difference`

of multiple sets using `^`

.

A={1,2} B={2,3,5} C={3,4} print (A^B^C)#Output:{1,4,5}

The difference between the `symmetric_difference`

method and the`&`

operator:

`symmetric_difference()`

: It’ll accept any iterable as an argument. This method doesn’t allow for multiple sets.`^`

operator: It’ll accept only a set as an argument. Otherwise, it’ll raise a`TypeError`

. By using the`^`

operator, you can find the`symmetric_difference`

between multiple sets.

**Example 3: Giving ****iterable**** as an argument in the ****symmetric_difference**** method**

#iterable is given as listA={1,2,3} B=[1] print (A.symmetric_difference(B))#Output:{2,3} #iterable is given as tupleA={1,2,3} B=(1,) print (A.symmetric_difference(B))#Output:{2,3} #iterable is given as range objectA={1,2,3} B=range(2) print (A.symmetric_difference(B))#Output:{2,3}

**Example 4: Giving ****iterable**** as an argument for the ****^**** operator**

A={1,2,3} B=[1] A^B print (A)#Output: TypeError: unsupported operand type(s) for ^: 'set' and 'list'

#### ‘symmetric_difference_update()’

Updates the set, keeping only elements found in either set but not in both. It’s performed by using `symmetric_difference_update()`

or by using the `^=`

operator. The return type is `None`

. It’ll modify the original set itself.

**Syntax**

**symmetric_difference_update**(*other*)

**set ^= other**

**Example 1: Find the ****symmetric_difference_update()**** between two sets — A and B**

It will update set `A`

by keeping only elements found in either set but not in both.

#symmetric_difference_update()A={1,2,3,4,5} B={4,5,6,7,8} print (A.symmetric_difference_update(B))#Output: Noneprint (A)#Output: {1, 2, 3, 6, 7, 8}A={1,2,3,4,5} B={4,5,6,7,8} A^=B print (A)#Output: {1, 2, 3, 6, 7, 8}

#### ‘isdisjoint()’

Returns `True`

if the set has no elements in common with the `other`

. Sets are disjointed if and only if their intersection is the empty set.

**Syntax**

**isdisjoint**(*other*)

**Example**

#Set A and Set B containing common elementsA={1,2,3,4,5} B={4,5,6,7,8} print (A.isdisjoint(B))#Output:False #Set A and Set B not containing common elementsA={1,2} B={3,4} print (A.isdisjoint(B))#Output:True

**‘issubset()’**

Test whether every element in the set is in `other`

.

**Syntax:**

**issubset**(*other*)

**set <= other**

**Example: Check whether set ****A**** is a subset of ****B**

Can be done by the `issubset()`

method or by using the `≤`

operator.

A={1,2,3,4,5} B={4,5,6,7,8} print (A.issubset(B))#Output: Falseprint (A<=B)#Output: FalseA={1,2,3} B={1,2,3,4,5} print (A.issubset(B))#Output: Trueprint (A<=B)#Output: False

**Proper subset**

Test whether the set is a proper subset of `other`

— that is, `set <= other and set != other`

.

**Syntax**

**set < other**

**Example: Check whether set ****A**** is a proper subset of ****B**

If both sets are equal, this means` A.issubsetset(B) `

returns `True`

. But the proper subset `A<B`

will return `False`

.

A={1,2,3,4,5} B={4,5,6,7,8} print (A<B)#Output: FalseA={1,2,3,4,5} B={1,2,3,4,5} print (A<B)#Output: FalseA={1,2,3} B={1,2,3,4,5} print (A<B)#Output: True

**‘issuperset()’**

Test whether every element in `other`

is in the set.

**Syntax**

**issuperset**(*other*)

**set >= other**

**Example: Check whether set ****A**** is a superset of ****B**

Can be done by the`issuperset()`

method or by using the `≥`

operator.

A={1,2,3,4,5} B={4,5,6,7,8} print (A.issuperset(B))#Output: Falseprint (A>=B)#Output:TrueA={1,2,3,4,5} B={1,2,3} print (A.issuperset(B))#Output: Trueprint (A>=B)#Output:True

**Proper superset**

Test whether the set is a proper superset of `other`

— that is, `set >= other and set != other`

.

**Syntax**

**set > other**

**Example: Check whether set ****A**** is a proper superset of ****B****.**

If both sets are equal, it means `A.issuperset(B)`

returns `True`

. But the proper superset `A>B`

will return `False`

.

A={1,2,3,4,5} B={4,5} print (A>B)#Output: TrueA={1,2,3,4,5} B={1,2,3,4,5} print (A>B)#Output: FalseA={1,2,3} B={1,2,3,4,5} print (A>B)#Output: True

### Note

All update methods are not supported by `frozenset`

. The `frozenset`

type is immutable and hashable — its contents can’t be altered after it’s created. Since all update methods modify the original set, it’s not supported by `frozenset`

.

### Conclusion

Mathematical set operations can be performed in two ways: by using an operator or by using a method.

The difference is if we use methods, they’ll accept `iterable`

as an argument. But for operators, arguments should be set only. If not, it’ll raise a `TypeError`

. All update methods will update the original set, and it’s not supported in `frozenset`

. Other than update methods, all other methods return a new set.

I hope you have found this article helpful — thanks for reading!

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