# Python Sets

Sets are used to store multiple items in a single variable. A set is a collection which is unordered, unchangeable*, and unindexed.

*Note: Set items are unchangeable, but you can remove items and add new items.*

## Creating a Set

Sets are written with curly brackets.

```python
thisset = {"apple", "banana", "cherry"}
print(thisset)
```

## Access Items

You cannot access items in a set by referring to an index or a key. However, you can loop through the set items using a `for` loop, or ask if a specified value is present in a set, by using the `in` keyword.

```python
thisset = {"apple", "banana", "cherry"}

for x in thisset:
  print(x)

print("banana" in thisset) # Output: True
```

## Add Items

To add one item to a set use the `add()` method.

```python
thisset.add("orange")
```

To add items from another set into the current set, use the `update()` method.

```python
tropical = {"pineapple", "mango", "papaya"}
thisset.update(tropical)
```

## Remove Items

To remove an item in a set, use the `remove()`, or the `discard()` method.

```python
thisset.remove("banana")
thisset.discard("banana")
```

## Set Operations

### Union

The `union()` method returns a new set with all items from both sets.

```python
set1 = {"a", "b" , "c"}
set2 = {1, 2, 3}

set3 = set1.union(set2)
print(set3)
```

[[programming/python/python]]