PHP Random Shuffle Array Maintaining Key => Value

Question

I\'ve been looking on google for the answer but can\'t seem to find something fool-proof and cant really afford to mess this up (going live into a production site).

Answer 1

  $testArray = array('a' => 'apple', 'b' => 'ball', 'c' => 'cat', 'd' => 'dog');
  $keys = array_keys($testArray); //Get the Keys of the array -> a, b, c, d
  shuffle($keys); //Shuffle The keys array -> d, a, c, b
  $shuffledArray = array();
  foreach($keys as $key) {
    $shuffledArray[$key] = $testArray[$key]; //Get the original array using keys from shuffled array
  }
  print_r($shuffledArray);
  /*
  Array
  (
      [d] => dog
      [a] => apple
      [c] => cat
      [b] => ball
  )
  */

Answer 2

I was having a hard time with most of the answers provided - so I created this little snippet that took my arrays and randomized them while maintaining their keys:

function assoc_array_shuffle($array)
{
    $orig = array_flip($array);
    shuffle($array);
    foreach($array AS $key=>$n)
    {
        $data[$n] = $orig[$n];
    }
    return array_flip($data);
}

Answer 3

I tried the most vote solution didn't popular shuffle list. This is the change I made to make it work. I want my array key starting from 1.

 $list = array_combine(range(1,10),range(100,110));
 $shuffle_list =  shuffle_assoc($list);


function shuffle_assoc($list)
{
    if (!is_array($list)) return $list;

    $keys = array_keys($list);
    shuffle($list);
    $random = array();
    foreach ($keys as $k => $key) {
        $random[$key] = $list[$k];
    }
    return $random;
}

Answer 4

Take a look to this function here :

     $foo = array('A','B','C'); 


function shuffle_with_keys(&$array) {
    /* Auxiliary array to hold the new order */
    $aux = array();
    /* We work with an array of the keys */
    $keys = array_keys($array);
    /* We shuffle the keys */`enter code here`
    shuffle($keys);
    /* We iterate thru' the new order of the keys */
    foreach($keys as $key) {
      /* We insert the key, value pair in its new order */
      $aux[$key] = $array[$key];
      /* We remove the element from the old array to save memory */
      unset($array[$key]);
    }
    /* The auxiliary array with the new order overwrites the old variable */
    $array = $aux;
  }

      shuffle_with_keys($foo);
      var_dump($foo);

Original post here : http://us3.php.net/manual/en/function.shuffle.php#83007

Answer 5

function shuffle_assoc($array)
{
    $keys = array_keys($array);
    shuffle($keys);
    return array_merge(array_flip($keys), $array);
}

Answer 6

The first user post under the shuffle documentation:

Shuffle associative and non-associative array while preserving key, value pairs. Also returns the shuffled array instead of shuffling it in place.

function shuffle_assoc($list) { 
  if (!is_array($list)) return $list; 

  $keys = array_keys($list); 
  shuffle($keys); 
  $random = array(); 
  foreach ($keys as $key) { 
    $random[$key] = $list[$key]; 
  }
  return $random; 
} 

Test case:

$arr = array();
$arr[] = array('id' => 5, 'foo' => 'hello');
$arr[] = array('id' => 7, 'foo' => 'byebye');
$arr[] = array('id' => 9, 'foo' => 'foo');
print_r(shuffle_assoc($arr));
print_r(shuffle_assoc($arr));
print_r(shuffle_assoc($arr));