Set Methods
Python sets come with powerful built-in methods that allow you to add, remove, compare, and combine sets efficiently.
Because sets show unique and unordered data, these methods are widely used in data cleaning, comparisons, and logic building.
Below is a complete, method-by-method explanation, with intro, syntax, and example for each.
add()
What it does
Adds one element to the set.
Syntax
python
set.add(element)
Example
python
fruits = {"apple", "banana"}
fruits.add("cherry")
print(fruits)
update()
What it does
Adds multiple elements from an iterable.
Syntax
python
set.update(iterable)
Example
python
numbers = {1, 2}
numbers.update([3, 4, 5])
print(numbers)
remove()
What it does
Removes a specified element.
Raises error if element not found.
Syntax
python
set.remove(element)
Example
python
fruits = {"apple", "banana"}
fruits.remove("banana")
print(fruits)
discard()
What it does
Removes element without raising error if missing.
Syntax
python
set.discard(element)
Example
python
fruits.discard("mango")
print(fruits)
pop()
What it does
Removes and returns a random element.
Syntax
python
set.pop()
Example
python
items = {1, 2, 3}
x = items.pop()
print(x)
print(items)
clear()
What it does
Removes all elements from the set.
Syntax
python
set.clear()
Example
python
numbers = {1, 2, 3}
numbers.clear()
print(numbers)
union()
What it does
Returns a new set containing all unique elements.
Syntax
python
set1.union(set2)
Example
python
a = {1, 2}
b = {2, 3}
print(a.union(b))
intersection()
What it does
Returns elements common to both sets.
Syntax
python
set1.intersection(set2)
Example
python
print(a.intersection(b))
difference()
What it does
Returns elements in first set but not in second.
Syntax
python
set1.difference(set2)
Example
python
print(a.difference(b))
symmetric_difference()
What it does
Returns elements not common to both sets.
Syntax
python
set1.symmetric_difference(set2)
Example
python
print(a.symmetric_difference(b))
intersection_update()
What it does
Updates the set keeping only common elements.
Syntax
python
set.intersection_update(set2)
Example
python
a = {1, 2, 3}
b = {2, 3, 4}
a.intersection_update(b)
print(a)
difference_update()
What it does
Removes elements found in another set.
Syntax
python
set.difference_update(set2)
Example
python
a = {1, 2, 3}
b = {2}
a.difference_update(b)
print(a)
symmetric_difference_update()
What it does
Keeps only elements not common.
Syntax
python
set.symmetric_difference_update(set2)
Example
python
a = {1, 2, 3}
b = {3, 4}
a.symmetric_difference_update(b)
print(a)
issubset()
What it does
Checks if one set is a subset of another.
Syntax
python
set1.issubset(set2)
Example
python
a = {1, 2}
b = {1, 2, 3}
print(a.issubset(b))
issuperset()
What it does
Checks if one set contains another set.
Syntax
python
set1.issuperset(set2)
Example
python
print(b.issuperset(a))
isdisjoint()
What it does
Checks if two sets have no common elements.
Syntax
python
set1.isdisjoint(set2)
Example
python
x = {1, 2}
y = {3, 4}
print(x.isdisjoint(y))
All Set Methods – Summary Table
| Method | Purpose |
|---|---|
add() | Add one element |
update() | Add multiple elements |
remove() | Remove element (error if missing) |
discard() | Remove safely |
pop() | Remove random element |
clear() | Remove all |
union() | Combine sets |
intersection() | Common elements |
difference() | Unique to first |
symmetric_difference() | Non-common |
issubset() | Subset check |
issuperset() | Superset check |
isdisjoint() | No common elements |
Key Notes
- Sets store only unique values
- Order is not preserved
- Mutable but elements must be immutable
- Extremely fast for membership testing
This topic completes the entire Python Set concept in a clean, interview-ready way.