如何对一组关联数组进行分组并声明自定义键？

Question

有人可以帮助我将 php 数组转换为分组格式吗？我正在尝试按id 对它们进行分组。我想转换以下数组：

$Arr1=Array
    (
        0 => Array
        (
            "id" => "4123",
            "test_number" => "1",
            "sat_total" => "1050"
        ),
        1 => Array
        (
            "id" => "4123",
            "test_number" => "2",
            "sat_total" => "1130"
        ),
        2 => Array
        (
            "id" => "4123",
            "test_number" => "3",
            "sat_total" => "1120"
        ),
        3 => Array
        (
            "id" => "5555",
            "test_number" => "1",
            "sat_total" => "1130"
        ),
        4 => Array
        (
            "id" => "5555",
            "test_number" => "2",
            "sat_total" => "1160"
        )
    );

进入这个：

$Arr2=Array
    (
        0 => Array
        (
            "id" => "4123",
            "Score1" => "1050",
            "Score2" => "1130",
            "Score3" => "1120"
        ),
        1 => Array
        (
            "id" => "5555",
            "Score1" => "1130",
            "Score2" => "1160"
        )
    );

我已经尝试了一点，但似乎找不到如何让它发挥作用。

Answer 1

此方法将查找与 $id 匹配的分数。
它使用三个 array_intersect 来匹配所有正确的值。
此方法只会循环唯一 ID 的数量，在您的情况下会循环两次。
加上创建乐谱键的时间。

我同意 ggorlen 关于钥匙的说法。这也将创建更高效​​的代码。

$ids = array_column($Arr1, "id");
$sat = array_column($Arr1, "sat_total");

foreach(array_unique($ids) as $id){
    $new[$id] = ["id" => $id];
    $tmp = array_values(array_intersect_key($sat,array_intersect_key($Arr1, array_intersect($ids, [$id]))));
    for($i=1;$i<=count($tmp);$i++) $new[$id]["Score" . $i] = $tmp[$i-1];
}
var_dump($new);

https://3v4l.org/ag3To

输出是一个以 id 为键的关联数组。
如果你想让它被索引，你可以使用 array_values。

---

只是为了展示使用一个分数数组的代码可以提高多少效率。
这就是它的样子：

$ids = array_column($Arr1, "id");
$sat = array_column($Arr1, "sat_total");

foreach(array_unique($ids) as $id){
    $new[] = ["id" => $id, "scores" => array_values(array_intersect_key($sat,array_intersect_key($Arr1, array_intersect($ids, [$id]))))];
}
var_dump($new);

https://3v4l.org/mdA0W

Answer 2

$arr2 = [];
$i = 0;
$length = count($arr1);
do {
    $builder = $arr1[$i];
    // grab the first item from the original array

    $builder = [
        // set its initial properties
        'id' => $arr1[$i]['id'],
        'Score1' => $arr1[$i]['sat_total'],
    ];

    // initialise the subsequent score number
    $testNumber = 2;

    // prepare to look ahead in the original array for a matching id
    while (($i + 1) < $length) { // only look ahead if it is possible to
        if ($arr1[$i + 1]['id'] == $builder['id']) {
            // did you find a matching id? if so, let's set the subsequent score
            $builder["Score$testNumber"] = $arr1[$i + 1]['sat_total'];
            $testNumber++; // increase the next score number
            $i++; // increase the original array index
        } else {
            // no luck? let's go forwards and set the next record
            break;
        }
    }
    $arr2[] = $builder; // set the built record into the new array
    $i++; // move the pointer forwards
} while ($i < $length); // as long as there are items ahead

你不经常使用do-while。但它有效:)

输入你的原始数组$arr1 和$arr2 将被设置。

它的工作原理是期待匹配ids。此解决方案假定您的原始数组按id 排序！因此，除非您相信输入 - 不要使用此解决方案！

否则，这是一个简单、快速且可读性强的解决方案，在我看来像是学校练习？

如果您想要安全的东西，这里的其他解决方案都是合适的。

Answer 3

您只需要迭代您的数据行，确定每一行是否是第一个出现的id 值，然后声明初始值，或者向组中添加一个可变键元素。循环结束后，调用array_values() 重新索引数组（删除临时键）。

代码：(Demo)

$Arr1=[
    ["id" => "4123", "test_number" => "1", "sat_total" => "1050"],
    ["id" => "4123", "test_number" => "2", "sat_total" => "1130"],
    ["id" => "4123", "test_number" => "3", "sat_total" => "1120"],
    ["id" => "5555", "test_number" => "1", "sat_total" => "1130"],
    ["id" => "5555", "test_number" => "2", "sat_total" => "1160"]
];

foreach ($Arr1 as $set) {
    if (!isset($result[$set['id']])) {
        $result[$set['id']] = ['id' => $set['id'], 'Score1' => $set['sat_total']];
    } else {
        $result[$set['id']]['Score' . sizeof($result[$set['id']])] = $set['sat_total'];
    }
}

var_export(array_values($result));

输出：

array (
  0 => 
  array (
    'id' => '4123',
    'Score1' => '1050',
    'Score2' => '1130',
    'Score3' => '1120',
  ),
  1 => 
  array (
    'id' => '5555',
    'Score1' => '1130',
    'Score2' => '1160',
  ),
)