check for duplicate results in multi dimensional array

Question

I have a multi dimensional array and I need to cross check it for duplicate results and if they are duplicated remove the array with the duplicate results. I need to check 3 keys for duplication; number, departure and arrival. Here is an example array where the 3rd array is a duplicate and would need to be deleted:

[Cars] => Array
    (
        [0] => Array
            (
                [cartype] => car1
                [number] => 123
                [craft] => 456
                [departure] => GHY
                [departtime] => 20:25
                [arrival] => PUI
                [arrivetime] => 22:50
            )

        [1] => Array
            (
                [cartype] => car2
                [number] => 567
                [craft] => 890
                [departure] => LHY
                [departtime] => 16:25
                [arrival] => PGY
                [arrivetime] => 23:50
            )
        [2] => Array
            (
                [cartype] => car2
                [number] => 567
                [craft] => 890
                [departure] => LHY
                [departtime] => 16:25
                [arrival] => PGY
                [arrivetime] => 23:50
            )

    )

I would really appreciate some help.

Thanks,

Do you have to check all the array elements, or just `number`? — Barmar, Feb 12 '17 at 18:24
You can convert each array to a string with `serialize()`, use `array_unique()` to remove the duplicates, then convert them back to arrays with `unserialize()`. — Barmar, Feb 12 '17 at 18:25
http://stackoverflow.com/questions/307674/how-to-remove-duplicate-values-from-a-multi-dimensional-array-in-php — bxN5, Feb 12 '17 at 18:31

score 1 · Accepted Answer · answered Feb 12 '17 at 18:49

The solution using in_array function and custom $hash_map container(each entry is comprised of number, departure and arrival keys values):

// $arr is your initial array

// hash container
$hash_map = [];
foreach ($arr['Cars'] as $k => &$v) {
    $hash = $v['number'] . $v['departure'] . $v['arrival'];
    if (in_array($hash, $hash_map)) {
        unset($arr['Cars'][$k]);   // removing duplicate item     
    } else {
        $hash_map[] = $hash;    
    }
}
unset($hash_map);

print_r($arr);

score 0 · Answer 2 · 2017-02-12T19:11:03.960

Try the following in order to completely remove identical duplicate sub-arrays.

$arr = [['cartype' => 'car1','number' => '123','departure' => 'GHY','arrival' => 'PUI'],
        ['cartype' => 'car2','number' => '567','departure' => 'LHY','arrival' => 'PGY'],
        ['cartype' => 'car2','number' => '567','departure' => 'LHY','arrival' => 'PGY']];
$out = [];  
while (list($k, $v) = each($arr)) {
if(!in_array($v,$out)) {
    array_push($out,$v);
}
}
print_r($out);
// output
Array
(
    [0] => Array
        (
            [cartype] => car1
            [number] => 123
            [departure] => GHY
            [arrival] => PUI
        )

    [1] => Array
        (
            [cartype] => car2
            [number] => 567
            [departure] => LHY
            [arrival] => PGY
        )
)

check the example here

EDIT In case you only want to use for checking duplicate results.

$arr = [['cartype' => 'car1','number' => '123','departure' => 'GHY','arrival' => 'PUI'],
        ['cartype' => 'car2','number' => '567','departure' => 'LHY','arrival' => 'PGY'],
        ['cartype' => 'car2','number' => '567','departure' => 'LHY','arrival' => 'PGY']];
$out = []; 
$checks = [];
while (list($k, $v) = each($arr)) {
if(!in_array([$v['number'],$v['departure'],$v['arrival']],$checks)) {
    array_push($checks,[$v['number'],$v['departure'],$v['arrival']]);
    array_push($out,$v);
}
}
print_r($out);
// output 
Array
(
    [0] => Array
        (
            [cartype] => car1
            [number] => 123
            [departure] => GHY
            [arrival] => PUI
        )

    [1] => Array
        (
            [cartype] => car2
            [number] => 567
            [departure] => LHY
            [arrival] => PGY
        )
)

check the new example here

check for duplicate results in multi dimensional array

2 Answers2