【PHP】合并二维数组内指定的相同键并计算另一键的和后组成新的二位数组

Question

array(4) {
  [0] => array(5) {
    ["id"] => int(1)
    ["order_num"] => string(11) "20170823-01"
    ["name"] => string(4) "4015"
    ["num"] => int(2000)
    ["time"] => int(1503590400)
  }
  [1] => array(5) {
    ["id"] => int(2)
    ["order_num"] => string(11) "20170823-02"
    ["name"] => string(4) "4015"
    ["num"] => int(3000)
    ["time"] => int(1503590400)
  }
  [2] => array(5) {
    ["id"] => int(3)
    ["order_num"] => string(11) "20170823-03"
    ["name"] => string(4) "4123"
    ["num"] => int(1000)
    ["time"] => int(1503590400)
  }
  [3] => array(5) {
    ["id"] => int(4)
    ["order_num"] => string(11) "20170823-04"
    ["name"] => string(4) "4123"
    ["num"] => int(1000)
    ["time"] => int(1503590400)
  }
}

原始数组如上
需要将 ["name"] 相同的合并到一起，且所对应的 ["num"]的值为原始数据中两个值的和
可能有多个相同["name"]
因为是新手，试了很多方法都没实现，想请教大牛们，应该怎么实现？
其他的键可以忽略

最终的结果是这种

array(4) {
  [0] => array(5) {
    ["name"] => string(4) "4015"
    ["num"] => int(5000)
        ["time"] => int(1503590400)
  }
  [1] => array(5) {
    ["name"] => string(4) "4123"
    ["num"] => int(2000)
    ["time"] => int(1503590400)
  }

}

Answer 1

拿好不谢

$arr = [
    [
        'name'=>111,
        'sum'=>2
    ],
    [
        'name'=>111,
        'sum'=>3
    ],
    [
        'name'=>222,
        'sum'=>5
    ],
];
$tmp = [];
foreach ($arr as $v) {
    if(!isset($tmp[$v['name']])){
        $tmp[$v['name']]['name'] = $v['name'];
        $tmp[$v['name']]['sum'] = $v['sum'];
    }else{
        $tmp[$v['name']]['name'] = $v['name'];
        $tmp[$v['name']]['sum'] += $v['sum'];
    }
}
$out = array_values($tmp);
var_dump($out);