PHP unique array by value?

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

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)));

basically

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