# Quick guide to Swift array partition

## Introduction

The `partition(by:)` method in Swift allows you to divide an array into two smaller groups, based on a predicate. This can be useful for tasks such as sorting, filtering, and grouping.

In this blog post, we will provide a quick guide to using Swift array partition. We will cover the basics of how to use the method, as well as some common use cases.

## How to use Swift array partition

The `partition(by:)` method takes a predicate as its only argument. The predicate is a function that takes an element of the array as its argument and returns a Boolean value. The `partition(by:)` method will divide the array into two groups: the elements for which the predicate returns `true` and the elements for which the predicate returns `false`.

The following code shows how to use the `partition(by:)` method to divide an array of numbers into two groups: even numbers and odd numbers:

```let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

// Predicate to check if a number is even
let isEvenPredicate: (Int) -> Bool = { \$0 % 2 == 0 }

// Divide the array into even and odd numbers
let (evenNumbers, oddNumbers) = numbers.partition(by: isEvenPredicate)

// Print the even and odd numbers
print(evenNumbers) // [2, 4, 6, 8, 10]
print(oddNumbers) // [1, 3, 5, 7, 9]
```

## Common use cases for Swift array partition

The `partition(by:)` method can be used for a variety of tasks, including:

• Sorting: You can use the `partition(by:)` method to sort an array in ascending or descending order. To do this, you would use a predicate that checks if an element is greater than or less than another element.
• Filtering: You can use the `partition(by:)` method to filter an array, removing all of the elements that do not match a given predicate.
• Grouping: You can use the `partition(by:)` method to group an array into two or more smaller groups, based on different criteria.

Here are some specific examples of how to use the `partition(by:)` method for sorting, filtering, and grouping:

```// Sort an array of numbers in ascending order
let numbers = [10, 3, 2, 5, 4, 1, 6, 7, 8, 9]
let sortedNumbers = numbers.partition(by: { \$0 < \$1 })

// Filter an array of strings to remove all of the empty strings
let strings = ["a", "", "b", "", "c"]
let filteredStrings = strings.partition(by: { \$0.isEmpty })

// Group an array of people by their age
let people = [Person(age: 20), Person(age: 30), Person(age: 40)]

let (under30, over30) = people.partition(by: { \$0.age < 30 })
```

## Conclusion

The `partition(by:)` method is a powerful tool that can be used to divide an array into two or more smaller groups, based on different criteria. It is a versatile method that can be used for a variety of tasks, such as sorting, filtering, and grouping.

We hope this quick guide to Swift array partition has been helpful. If you have any questions, please feel free to leave a comment below.

A pat on the back !!