How to Randomize the Order of an Array in PHP ?

Randomizing the order of an array is a common operation in PHP, especially when dealing with datasets or when you want to shuffle the presentation of items. In this article, we will explore various approaches to randomize the order of an array.

Using shuffle() Function

The shuffle() function is a built-in PHP function specifically designed for randomizing the order of an array.

<?php

$arr = [1, 2, 3, 4, 5];

// Randomize the order of array
// using shuffle() function
shuffle($arr);

// Display the randomized array
print_r($arr);

?>

Array
(
    [0] => 4
    [1] => 5
    [2] => 2
    [3] => 1
    [4] => 3
)

Using usort() Function with Custom Comparison Function

The usort() function allows you to sort an array using a user-defined comparison function. By using a comparison function that returns a random value, you can achieve array randomization.

<?php

$arr = [1, 2, 3, 4, 5];

// Randomize the order of the array
usort($arr, function () {
    return rand(-1, 1);
});

// Display the randomized array
print_r($arr);

?>

Array
(
    [0] => 2
    [1] => 1
    [2] => 3
    [3] => 4
    [4] => 5
)

Using array_rand() Function

The array_rand() function can be used to pick one or more random keys from an array. By using this function, you can shuffle an array by picking random keys and building a new array.

Example:

<?php 

$arr = [1, 2, 3, 4, 5]; 

// Get an array of random keys
$randomKeys = array_rand($arr, count($arr));

// Create a new array with values in random order
$shuffledArray = [];
foreach ($randomKeys as $key) {
    $shuffledArray[] = $arr[$key];
}

// Display the randomized array 
print_r($shuffledArray); 

?>

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)

Approach 4: Using array_map() and shuffle()

This method combines the use of array_map() with shuffle() to create a shuffled array in a unique way. It involves mapping the original array to a new array of random keys, shuffling these keys, and then reconstructing the array based on the shuffled order of keys.

Example: Here’s how you can implement this method to randomize the order of an array:

<?php
$items = ['apple', 'banana', 'cherry', 'date', 'elderberry'];

// Generate a list of keys based on the original array
$keys = array_keys($items);

// Shuffle the keys
shuffle($keys);

// Rebuild the array using shuffled keys
$shuffledItems = array_map(function ($key) use ($items) {
    return $items[$key];
}, $keys);

print_r($shuffledItems);

?>

Array
(
    [0] => apple
    [1] => banana
    [2] => date
    [3] => elderberry
    [4] => cherry
)