PHP Random Shuffle Array Maintaining Key => Value - php

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).
What I have is an advanced search with 20+ filters, which returns an array including an ID and a Distance. What I need to do is shuffle these results to display in a random order every time. The array I have that comes out at the moment is:
Array (
[0] => Array ( [id] => 1 [distance] => 1.95124994507577 )
[1] => Array ( [id] => 13 [distance] => 4.75358968511882 )
[2] => Array ( [id] => 7 [distance] => 33.2223233233323 )
[3] => Array ( [id] => 21 [distance] => 18.2155453552336 )
[4] => Array ( [id] => 102 [distance] = 221.2212587899658 )
)
What I need to be able to do is randomise or order of these every time but maintain the id and distance pairs, i.e.:
Array (
[4] => Array ( [id] => 102 [distance] = 221.2212587899658 )
[1] => Array ( [id] => 13 [distance] => 4.75358968511882 )
[3] => Array ( [id] => 21 [distance] => 18.2155453552336 )
[2] => Array ( [id] => 7 [distance] => 33.2223233233323 )
[0] => Array ( [id] => 1 [distance] => 1.95124994507577 )
)
Thanks :)

Answer 1

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));

Answer 2

As of 5.3.0 you could do:
uksort($array, function() { return rand() > rand(); });

Answer 3

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 4

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

Answer 5

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 6

Charles Iliya Krempeaux has a nice writeup on the issue and a function that worked really well for me:
function shuffle_assoc($array)
{
// Initialize
$shuffled_array = array();
// Get array's keys and shuffle them.
$shuffled_keys = array_keys($array);
shuffle($shuffled_keys);
// Create same array, but in shuffled order.
foreach ( $shuffled_keys AS $shuffled_key ) {
$shuffled_array[ $shuffled_key ] = $array[ $shuffled_key ];
} // foreach
// Return
return $shuffled_array;
}

Answer 7

Try using the fisher-yates algorithm from here:
function shuffle_me($shuffle_me) {
$randomized_keys = array_rand($shuffle_me, count($shuffle_me));
foreach($randomized_keys as $current_key) {
$shuffled_me[$current_key] = $shuffle_me[$current_key];
}
return $shuffled_me;
}
I had to implement something similar to this for my undergraduate senior thesis, and it works very well.

Answer 8

Answer using shuffle always return the same order. Here is one using random_int() where the order is different each time it is used:
function shuffle_assoc($array)
{
while (count($array)) {
$keys = array_keys($array);
$index = $keys[random_int(0, count($keys)-1)];
$array_rand[$index] = $array[$index];
unset($array[$index]);
}
return $array_rand;
}

Answer 9

$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 10

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;
}