PHP unique array by value?

Question

I have an array in PHP that looks like this:

  [0]=>
       array(2) {
           [\"name\"]=>
              string(9) \"My_item\"
           [\"url\"]         


        

Answer 1

Serialisation is very useful for simplifying the process of establishing the uniqueness of a hierarchical array. Use this one liner to retrieve an array containing only unique elements.

$unique = array_map("unserialize", array_unique(array_map("serialize", $input)));

Answer 2

Simple Solution:

/**
 * @param $array
 * @param null $key
 * @return array
 */
public static function unique($array,$key = null){
    if(null === $key){
        return array_unique($array);
    }
    $keys=[];
    $ret = [];
    foreach($array as $elem){
        $arrayKey = (is_array($elem))?$elem[$key]:$elem->$key;
        if(in_array($arrayKey,$keys)){
            continue;
        }
        $ret[] = $elem;
        array_push($keys,$arrayKey);
    }
    return $ret;
}

Answer 3

Given that the keys on the array (0,1) do not seem to be significant a simple solution would be to use the value of the element referenced by 'name' as the key for the outer array:

["My_item"]=>
   array(2) {
       ["name"]=>
          string(9) "My_item"
       ["url"]=>
          string(24) "http://www.my-url.com/"
   }

...and if there is only one value other than the 'name' why bother with a nested array at all?

["My_item"]=>"http://www.my-url.com/"

Answer 4

Please find this link useful, uses md5 hash to examine the duplicates:

http://www.phpdevblog.net/2009/01/using-array-unique-with-multidimensional-arrays.html

Quick Glimpse:

/**
 * Create Unique Arrays using an md5 hash
 *
 * @param array $array
 * @return array
 */
function arrayUnique($array, $preserveKeys = false)
{
    // Unique Array for return
    $arrayRewrite = array();
    // Array with the md5 hashes
    $arrayHashes = array();
    foreach($array as $key => $item) {
        // Serialize the current element and create a md5 hash
        $hash = md5(serialize($item));
        // If the md5 didn't come up yet, add the element to
        // to arrayRewrite, otherwise drop it
        if (!isset($arrayHashes[$hash])) {
            // Save the current element hash
            $arrayHashes[$hash] = $hash;
            // Add element to the unique Array
            if ($preserveKeys) {
                $arrayRewrite[$key] = $item;
            } else {
                $arrayRewrite[] = $item;
            }
        }
    }
    return $arrayRewrite;
}

$uniqueArray = arrayUnique($array);
var_dump($uniqueArray);

See the working example here: http://codepad.org/9nCJwsvg

Answer 5

function unique_multidim_array($array, $key) { 
            $temp_array = array(); 
            $i = 0; 
            $key_array = array(); 

            foreach($array as $val) { 
                if (!in_array($val[$key], $key_array)) { 
                    $key_array[$i] = $val[$key]; 
                    $temp_array[$i] = $val; 
                } 
                $i++; 
            } 
            return $temp_array; 
        } 
$result = unique_multidim_array($visitors,'ip');

Answer 6

basically

foreach($your_array as $element) {
    $hash = $element[field-that-should-be-unique];
    $unique_array[$hash] = $element;
}