Get random elements from an array in PHP

This post will discuss how to generate random entries from an array in PHP.

1. Using `array_rand()` function

A simple and efficient solution is to use the array_rand() function to pick one or more random entries out of an array. Here’s a PHP program to pick a random key from an array $arr:

<?php

$arr = array('first' => 'a', 'second' => 'b');

echo array_rand($arr); // first or second

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The array_rand() function returns the key of the random entry. To select a random value (not a key) of the random entry, use the snippet below:

<?php

$arr = array('first' => 'a', 'second' => 'b');

echo $arr[array_rand($arr)]; // `a` or `b`

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Here’s an example using a closure.

<?php

$random = function($arr) {return $arr[array_rand($arr)];};

$arr = array(6, 4, -1, 9, -2);

echo $random($arr);

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The second argument of the array_rand() function specifies how many random entries should be picked. Here’s a PHP program to pick $n random values from an array $arr:

<?php

$arr = array(6, 4, -1, 9, -2);

$n = 2;

$rand_keys = array_rand($arr, $n);

echo $arr[$rand_keys[0]] . "\n";

echo $arr[$rand_keys[1]] . "\n";

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See PHP Manual for more details.

2. Using `mt_rand()` function

Before PHP 7.1.0, the internal randomization algorithm for array_rand() uses the libc rand function, which is slower and less-random than Mersenne Twister Number Generator. If your array keys are numeric, here’s a better alternative to pick a random value from an array $arr:

<?php

$arr = array(6, 4, -1, 9, -2);

echo $arr[mt_rand(0, count($arr) - 1)];

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The mt_rand() function is a better alternative for the older rand(). However, both array_rand() and mt_rand() does not generate cryptographically secure values. For cryptographic purposes, consider using random_int(), random_bytes(), or openssl_random_pseudo_bytes() instead.

Refer to PHP Manual for more details.

That’s all about generating random entries from an array in PHP.

Get random elements from an array in PHP

1. Using array_rand() function

2. Using mt_rand() function

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1. Using `array_rand()` function

2. Using `mt_rand()` function