set

1. Creating a Set

1. Directly use curly braces to create.

set1 = {1, 2, 3, 4, 5}

2. Use the set() method.

image-20240207072723007

2. Set Intersection

Intersection: Find elements that appear in both sets, implemented using the & operator.

set1 = {1, 2, 3, 4, 5}
set2 = set([1, 2, 5, 6, 8])
print(set1 & set2)

# output
{1, 2, 5}

3. Set Union

Union: Find elements that are common in both sets, implemented using the | operator.

set1 = {1, 2, 3, 4, 5}
set2 = set([1, 2, 5, 6, 8])
print(set1 | set2)

# output
{1, 2, 3, 4, 5, 6, 8}

4. Set Difference

Difference: When finding the difference between set1 and set2, it returns elements in set1 but not in set2, implemented using the - operator.

set1 = {1, 2, 3, 4, 5}
set2 = set([1, 2, 5, 6, 8])
print(set1 - set2)

# output
{3, 4}

5. Set Symmetric Difference

Symmetric Difference: When finding the symmetric difference between set1 and set2, it returns elements that exist in set1 or set2 but not in both, implemented using the ^ operator –> equivalent to the union minus the intersection, Venn diagram.

set1 = {1, 2, 3, 4, 5}
set2 = set([1, 2, 5, 6, 8])
print(set1 ^ set2)

# output
{3, 4, 6, 8}

6. Reflection

Can symmetric difference be achieved using the other three set operations? How?

Using union minus intersection.

set1 = {1, 2, 3, 4, 5}
set2 = set([1, 2, 5, 6, 8])
U = set1 | set2
N = set1 & set2
print(U - N)

# output
{8, 3, 4, 6}

7. .add() - Adding Elements to a Set

set1 = {1, 2, 3, 4, 5}
set2 = set([1, 2, 5, 6, 8])
set1.add(9)
print(set1)

# output
{1, 2, 3, 4, 5, 9}