array unique on multidimensional array

array_unique.php

<?php

function arr_unique($arr, $index){
    $tmpArray = [];
    $newArray =[];
    foreach ($arr as $val) {
        if(!in_array($val[$index],$tmpArray)) {
            $newArray[]=$val;
            $tmpArray[]=$val[$index];
        }
    }
    return $newArray;
}
$arr=[
    [1,2,3],
    [2,3,4],
    [1,3,4],
    [2,4,5]
];
print_r(arr_unique(array_reverse($arr),0));