If you’re working with sets in Python, you may come across the term “union”. Sets are unordered collections of unique elements, and they can be useful in a variety of applications, such as data analysis and web development. In this article, we’ll dive into what a set union is, how it works, and how to use it in your Python code.

## What is a Set Union?

A set union is a mathematical operation that combines two sets into a single set that contains all the unique elements from both sets. It’s denoted by the symbol ∪.

In Python, you can use the `union()`

method or the `|`

operator to perform a set union. Both return a new set that contains all the unique elements from the input sets.

### How to Use the `union()`

Method

The `union()`

method can be called on any set object in Python. Here’s the syntax:

`set1.union(set2)`

This will return a new set that contains all the unique elements from `set1`

and `set2`

.

Let’s take a look at some examples to see how this works.

### Example 1: Basic Set Union

```
set1 = {1, 2, 3}
set2 = {2, 3, 4}
union_set = set1.union(set2)
print(union_set)
```

Output:

`{1, 2, 3, 4}`

In this example, we have two sets (`set1`

and `set2`

) that have some overlapping elements. When we call `set1.union(set2)`

, we get a new set that contains all the unique elements from both sets.

### Example 2: Union with Duplicate Elements

```
set1 = {1, 2, 3}
set2 = {2, 3, 3, 4}
union_set = set1.union(set2)
print(union_set)
```

Output:

`{1, 2, 3, 4}`

In this example, `set2`

has a duplicate element (3). However, the `union()`

method only includes unique elements in the resulting set.

### Example 3: Union with Strings

```
set1 = {"apple", "banana", "cherry"}
set2 = {"banana", "cherry", "orange"}
union_set = set1.union(set2)
print(union_set)
```

Output:

`{'banana', 'cherry', 'apple', 'orange'}`

The `union()`

method works the same way with sets of strings as it does with sets of integers.

### Example 4: Union with Empty Sets

```
set1 = {1, 2, 3}
set2 = set()
union_set = set1.union(set2)
print(union_set)
```

Output:

`{1, 2, 3}`

If one of the sets is empty, the `union()`

method will simply return the non-empty set.

### Example 5: Union with Multiple Sets

```
set1 = {1, 2, 3}
set2 = {2, 3, 4}
set3 = {3, 4, 5}
union_set = set1.union(set2, set3)
print(union_set)
```

Output:

```
{1, 2, 3, 4, 5}
```

You can also pass multiple sets to the `union()`

method. It will combine all the unique elements from all the sets into a single set.

### Example 6: Union using the `|`

Operator

```
set1 = {1, 2, 3}
set2 = {2, 3, 4}
union_set = set1 | set2
print(union_set)
```

Output:

```
{1, 2, 3, 4}
```

As an alternative to the `union()`

method, you can use the `|`

operator to perform a set union. In this example, `set1 | set2`

returns a new set containing all the unique elements from both `set1`

and `set2`

.

## Conclusion

In this article, we’ve covered what a set union is and how to use the `union()`

method and the `|`

operator in Python. By using these techniques, you can easily combine two or more sets into a single set that contains all the unique elements. This can be useful in a variety of applications, from data analysis to web development.