Sets

 Sets

In Python, a set is an unordered collection of unique elements. Sets are similar to lists or dictionaries, but they have a unique property: they do not allow duplicate values. Additionally, sets are mutable, meaning you can modify them after creation. However, the elements of a set must be immutable.

Key features of sets:

1. Unordered:

   Sets do not maintain the order of elements. When you iterate over a set, the order in which elements are retrieved may vary.

2. Unique Elements:

   Sets only contain unique elements. If you try to add an element that already exists in the set, it won't be duplicated.

3. Mutable:

   You can add and remove elements from a set after it's created.

Here's how you can create a set:

```python

my_set = {1, 2, 3}

```

Alternatively, you can use the `set()` function:

```python

my_set = set([1, 2, 3])

```

To access elements in a set, you cannot use indexing because sets are unordered. However, you can check for membership (if an element is in the set) using the `in` keyword.

```python

print(1 in my_set)  # Output: True

print(4 in my_set)  # Output: False

```

To add elements to a set, you can use the `add()` method.

```python

my_set.add(4)

```

To remove elements, you can use the `remove()` method. If the element is not present, a `KeyError` is raised. Alternatively, you can use `discard()` to remove an element without raising an error if it's not present.

```python

my_set.remove(2)

my_set.discard(3)

```

Sets are useful for various operations such as finding unique elements, performing mathematical set operations (union, intersection, difference), and removing duplicates from other collections.

```python

set1 = {1, 2, 3}

set2 = {3, 4, 5}

# Union of sets

union_set = set1.union(set2)  # {1, 2, 3, 4, 5}

# Intersection of sets

intersection_set = set1.intersection(set2)  # {3}

# Difference of sets

difference_set = set1.difference(set2)  # {1, 2}

```

In summary, sets in Python are a versatile data structure for handling unique elements and performing set operations efficiently.