PHP: Sorting arrays randomly

demo

A custom PHP function. This function will return an array that’s been resorted in a random order. Supports both numerically-indexed and associative arrays. Uses PHP’s native array_rand() function.

1. function array_randsort($array,$preserve_keys=false){
   
2.         /*-------------------------------------/
   
3.         Preserving the keys works best with associative arrays.
   
4.         If you choose to preserve keys on a numerically-indexed or
   
5.     mixed-indexed array, use a foreach loop rather than a for loop
   
6.     to preserve the sorted order.
   
7.         /-------------------------------------*/
   
8.        
   
9.         if(!is_array($array)):
   
10.                 exit('Supplied argument is not a valid array.');
    
11.         else:
    
12.                 $i = NULL;
    
13.        
    
14.                 // how long is the array?
    
15.                 $array_length = count($array);
    
16.        
    
17.                 // Sorts the array keys in a random order.
    
18.                 $randomize_array_keys = array_rand($array,$array_length);
    
19.                
    
20.                 // if we are preserving the keys ...
    
21.                 if($preserve_keys===true) {               
    
22.                         // reorganize the original array in a new array
    
23.                         foreach($randomize_array_keys as $k=>$v){
    
24.                                 $randsort[$randomize_array_keys[$k]] = $array[$randomize_array_keys[$k]];
    
25.                         }
    
26.                 } else {
    
27.                         // reorganize the original array in a new array
    
28.                         for($i=0; $i < $array_length; $i++){
    
29.                                 $randsort[$i] = $array[$randomize_array_keys[$i]];
    
30.                         }
    
31.                 }
    
32.                 return $randsort;
    
33.         endif;
    
34. }

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There is also a shuffle() function in PHP.  It randomizes arrays also, but destroys the keys in associative arrays .  The other drawback of shuffle() is that it performs its tasks on the actual reference array parameter. So for data integrity a solution like this is probably better.

Copy and paste this script and refresh the page to see the shuffling effect.

1. <?php
   
2.     /**
   
3.     * Shuffles and displays cards in a deck
   
4.     * @author:     Eric Anderson
   
5.     * @filename:   deckofcards.php
   
6.     */
   
7.    
   
8.     // Create an array of face values
   
9.     // and an array of card values
   
10.     // then merge them together
    
11.     $cards = array_merge(array("J", "Q", "K", "A"), range(2,10)); // 13 cards
    
12.    
    
13.     // Shuffle the cards
    
14.     shuffle($cards);
    
15.    
    
16.     // Create an multidimentional array to hold the 4 suits
    
17.     $suits = array(
    
18.         'Heart' => array(),
    
19.         'Spade' => array(),
    
20.         'Diamond' => array(),
    
21.         'Club' => array()
    
22.         );
    
23.       
    
24.     // Add cards to their respective suits
    
25.     for($i = 0; $i < count($suits); $i++)
    
26.     {
    
27.         for($j = 0; $j < count($cards); $j++)
    
28.         {
    
29.             $suits['Heart'][$j] = $cards[$j]."<span style=color:#FF0000;>♥</span>";
    
30.             $suits['Spade'][$j] = $cards[$j]."♠";
    
31.             $suits['Diamond'][$j] = $cards[$j]."<span style=color:#FF0000;>♦</span>";
    
32.             $suits['Club'][$j] = $cards[$j]."♣";
    
33.         }
    
34.     }
    
35.    
    
36.     // Create a deck
    
37.     $deck = array();
    
38.    
    
39.     // Merge the suits into the empty deck array
    
40.     $deck = array_merge($deck, $suits);
    
41.                
    
42.     // Display the deck to the screen
    
43.     echo "<p><b>Deck of cards:</b></p>";
    
44.     foreach($deck as $k1 => $v1)
    
45.     {
    
46.         // Display suit name
    
47.         echo "<p> $k1's<br /> {<br />  ";
    
48.         $acc = 0;
    
49.       
    
50.         // Display card value
    
51.         foreach($v1 as $k2 => $v2)
    
52.         {
    
53.             echo "$v2 ";
    
54.             $acc++;
    
55.            
    
56.             if ($acc == 4)
    
57.             {
    
58.                 echo "<br />  ";
    
59.                 $acc = 0;
    
60.             }
    
61.         }
    
62.         echo "<br /> }</p>";
    
63.     }
    
64. ?>

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Tiffany B. Brown