How to randomly extract several elements from a php array (three methods)

In PHP development, we often need to randomly extract several elements from an array. Sometimes, we need to randomly select a few lucky users from a user list to give gifts. Or, we need to randomly select several dishes from a menu array as recommended dishes. This article will introduce how to randomly extract several elements from an array in PHP.

Method 1: Use shuffle and array_slice functions

The shuffle function can disrupt the elements of the array and randomly rearrange each element in the array. Then, use the array_slice function to extract a certain number of elements from the array. This method is simple and easy to understand and suitable for small arrays.

The code is as follows:

<?php
$array = array(&#39;apple&#39;, &#39;banana&#39;, &#39;orange&#39;, &#39;watermelon&#39;, &#39;grape&#39;, &#39;pear&#39;);
shuffle($array);
$rand_keys = array_rand($array, 3);
$result = array_slice($array, $rand_keys[0], 3);
print_r($result);
?>

Analysis:

1. Define an array $array, containing 6 elements.
2. Use the shuffle function to randomly sort the array elements.
3. Use the array_rand function to randomly extract the index positions of 3 elements from the scrambled array.
4. Use the array_slice function to get 3 random elements from the array.
5. Finally print out the results.

Method 2: Use the array_rand function

The array_rand function can directly return the index of one or more random elements from the array. This method works for large arrays.

The code is as follows:

<?php
$array = array(&#39;apple&#39;, &#39;banana&#39;, &#39;orange&#39;, &#39;watermelon&#39;, &#39;grape&#39;, &#39;pear&#39;);
$rand_keys = array_rand($array, 3);
$result = array();
foreach ($rand_keys as $key) {
    $result[] = $array[$key];
}
print_r($result);
?>

Analysis:

1. Define an array $array, containing 6 elements.
2. Use the array_rand function to retrieve the index positions of 3 random elements from the array.
3. Use a foreach loop to add randomly retrieved elements to the result array.
4. Finally print out the results.

Method 3: Use the mt_rand function

The mt_rand function can return a random integer within a specified range, so it can be used to generate random array keys. This method is relatively inefficient and suitable for small arrays.

The code is as follows:

<?php
$array = array(&#39;apple&#39;, &#39;banana&#39;, &#39;orange&#39;, &#39;watermelon&#39;, &#39;grape&#39;, &#39;pear&#39;);
$keys = array_keys($array);
$total = count($keys);
$pick_num = 3;
$rand_keys = array();
$result = array();
while (count($rand_keys) < $pick_num) {
    $rand_keys[] = $keys[mt_rand(0, $total-1)];
}
foreach ($rand_keys as $key) {
    $result[] = $array[$key];
}
print_r($result);
?>

Analysis:

1. Define an array $array, containing 6 elements.
2. Use the array_keys function to get the array $key, which is the collection of keys.
3. Get the total length of the array $total.
4. Define variable $pick_num, indicating the number of elements to be taken out.
5. Define a $rand_keys array to store randomly retrieved keys.
6. Use a loop to generate actual random keys. When the number of $rand_keys reaches $pick_num, break out of the loop.
7. Use a foreach loop to add randomly retrieved elements to the result array.
8. Finally print out the results.

The above are three ways to randomly select several elements from a PHP array. Different methods can be selected according to the actual situation. For large arrays, the array_rand function can be selected, etc. This operation seems simple, but it can improve the product experience, enhance the fun, and enrich the user experience.

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