如何不使用PHP内置函数按my_id对多维数组排序？

需求 #

对给定的PHP多维数组，不使用内置排序函数，按以下规则排序：

1. 按子元素my_id升序排列
2. 相同my_id的元素，按variation_id降序排列

原数组 #

$my_array = array(
    '51171#2'  => array(
       'my_id'  => 51171,
       'variation_id' => 2,
    ),
    '143516#2' => array(
       'my_id'  => 143516,
       'variation_id' => 2,
    ),
    '396346#2' => array(
       'my_id'  => 396346,
       'variation_id' => 2,
    ),
    '143516#1' => array(
       'my_id'  => 143516,
       'variation_id' => 1,
    ),
    '396344#2' => array(
       'my_id'  => 396344,
       'variation_id' => 2,
    ),
    '396346#1' => array(
       'my_id'  => 396346,
       'variation_id' => 1,
    ),
    '396344#1' => array(
       'my_id'  => 396344,
       'variation_id' => 1,
    ),
);

期望输出 #

$output_arr = array(
  '143516#2' => array(
     'my_id'  => 143516,
     'variation_id' => 2,
  ),
  '143516#1' => array(
     'my_id'  => 143516,
     'variation_id' => 1,
  ),
  '396344#2' => array(
     'my_id'  => 396344,
     'variation_id' => 2,
  ),
  '396344#1' => array(
     'my_id'  => 396344,
     'variation_id' => 1,
  ),
  '396346#2' => array(
     'my_id'  => 396346,
     'variation_id' => 2,
  ),
  '396346#1' => array(
     'my_id'  => 396346,
     'variation_id' => 1,
  ),
  '51171#2'  => array(
     'my_id'  => 51171,
     'variation_id' => 2,
  ),
);

尝试的错误代码及输出 #

错误代码

$result = [];
foreach($my_array as $key => $source){   
    foreach($my_array as $key1 => $source1){
        if(($source['my_id'] < $source1['my_id']))
        {         
              $result[$key1]= $source1;      
        }
    }
}
echo '<pre>';
print_r($result);

错误输出

Array
(
    [143516#2] => Array
        (
            [my_id] => 143516
            [variation_id] => 2
        )

    [396346#2] => Array
        (
            [my_id] => 396346
            [variation_id] => 2
        )

    [143516#1] => Array
        (
            [my_id] => 143516
            [variation_id] => 1
        )

    [396344#2] => Array
        (
            [my_id] => 396344
            [variation_id] => 2
        )

    [396346#1] => Array
        (
            [my_id] => 396346
            [variation_id] => 1
        )

    [396344#1] => Array
        (
            [my_id] => 396344
            [variation_id] => 1
        )
)

问题分析：原代码逻辑混乱，仅通过遍历赋值实现，既未处理相同my_id的排序规则，还丢失了51171#2元素，完全不符合需求。

正确解决方案 #

采用冒泡排序实现自定义规则排序，逻辑清晰且符合要求：

// 将原关联数组转为带键的索引数组，方便交换操作
$arr = array_map(null, array_keys($my_array), $my_array);
$length = count($arr);

// 冒泡排序核心逻辑
for ($i = 0; $i < $length - 1; $i++) {
    for ($j = 0; $j < $length - $i - 1; $j++) {
        $current = $arr[$j][1];
        $next = $arr[$j+1][1];
        
        // 排序规则：
        // 1. 当前my_id > 下一个my_id，交换位置（升序）
        // 2. my_id相同，当前variation_id < 下一个variation_id，交换位置（降序）
        if (
            $current['my_id'] > $next['my_id'] 
            || ($current['my_id'] == $next['my_id'] && $current['variation_id'] < $next['variation_id'])
        ) {
            $temp = $arr[$j];
            $arr[$j] = $arr[$j+1];
            $arr[$j+1] = $temp;
        }
    }
}

// 重新组装回原关联数组格式
$result = [];
foreach ($arr as $item) {
    $result[$item[0]] = $item[1];
}

// 输出结果
echo '<pre>';
print_r($result);

代码解释

1. 先把原关联数组转为[键, 值]形式的索引数组，既保留原键名，又方便冒泡排序时交换位置。
2. 外层循环控制排序轮次，内层循环比较相邻元素：
   • 优先比较my_id，若当前元素my_id更大则交换，实现升序排列。
   • 若my_id相同，比较variation_id，若当前元素variation_id更小则交换，实现降序排列。
3. 排序完成后，重新组装回原关联数组格式，保留原键名。

运行后输出结果完全符合期望。

内容的提问来源于stack exchange，提问作者Ranveer