Drew Baker Drew Baker - 12 days ago 7
PHP Question

Remove duplicates from an array based on object property?

I have an array of objects. I'd like to remove the duplicates based on the "name" value in the object.

[0]=>
object(stdClass)#337 (9) {
["term_id"]=>
string(2) "23"
["name"]=>
string(12) "Assasination"
["slug"]=>
string(12) "assasination"
}
[1]=>
object(stdClass)#44 (9) {
["term_id"]=>
string(2) "14"
["name"]=>
string(16) "Campaign Finance"
["slug"]=>
string(16) "campaign-finance"
}
[2]=>
object(stdClass)#298 (9) {
["term_id"]=>
string(2) "15"
["name"]=>
string(16) "Campaign Finance"
["slug"]=>
string(49) "campaign-finance-good-government-political-reform"
}


So in this case, how do I remove the duplicate "Campaign Finance" object from the array. So the entire [2] object?

I've gone through a bunch of the PHP duplicate array question here, but none seemed to deal with objects and filtering just off of one parameter.

Answer

Build a new array with the existing keys and just the name as value, use array_unique (note that it preserves keys).

Then remove everything thats not in the unique'ed array from the original key-wise.

Edit: Complete example:

class my_obj
{
        public $term_id;
        public $name;
        public $slug;

        public function __construct($i, $n, $s)
        {
                $this->term_id = $i;
                $this->name = $n;
                $this->slug = $s;
        }
}

$objA = new my_obj(23, "Assasination", "assasination");
$objB = new my_obj(14, "Campaign Finance", "campaign-finance");
$objC = new my_obj(15, "Campaign Finance", "campaign-finance-good-government-political-reform");

$array = array($objA, $objB, $objC);

echo "Original array:\n";
print_r($array);

/** Answer Code begins here **/

// Build temporary array for array_unique
$tmp = array();
foreach($array as $k => $v)
    $tmp[$k] = $v->name;

// Find duplicates in temporary array
$tmp = array_unique($tmp);

// Remove the duplicates from original array
foreach($array as $k => $v)
{
    if (!array_key_exists($k, $tmp))
        unset($array[$k]);
}

/** Answer Code ends here **/

echo "After removing duplicates\n";
print_r($array);

Output:

Original array:
Array
(
    [0] => my_obj Object
        (
            [term_id] => 23
            [name] => Assasination
            [slug] => assasination
        )

    [1] => my_obj Object
        (
            [term_id] => 14
            [name] => Campaign Finance
            [slug] => campaign-finance
        )

    [2] => my_obj Object
        (
            [term_id] => 15
            [name] => Campaign Finance
            [slug] => campaign-finance-good-government-political-reform
        )

)
After removing duplicates
Array
(
    [0] => my_obj Object
        (
            [term_id] => 23
            [name] => Assasination
            [slug] => assasination
        )

    [1] => my_obj Object
        (
            [term_id] => 14
            [name] => Campaign Finance
            [slug] => campaign-finance
        )

)

The object with term_id 15 was removed as it had the same name as term_id 14.

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