修改 2d 数组以在遇到特定键时创建嵌套数据集-解网

问：

我有一个这样的输入数组

$input = [
    ["relation" => "OR"],
    ["color" => 'green'],
    ["color" => 'yellow'],
    ["relation" => "AND"],
    ["color" => 'black'],
    ["color" => 'orange'],
    ["relation" => "OR"],
    ["color" => 'blue'],
    ["color" => 'violet'],
];

期望结果：

$output = array(
    'relation' => 'OR',
    array(
        "color" => 'green'
    ),
    array(
        "color" => 'yellow'
    ),
    array(
        "relation" => "AND",
        array(
            "color" => "black"
        ),
        array(
            "color" => "orange"
        ),
        array(
            "relation" => "OR",
            array(
                "color" => "blue"
            ),
            array(
                "color" => "violet"
            ),
        )
    )
);

我相信我需要做递归函数来处理这个问题。

我有这个，但只适用于一个级别

function generate_nested_array($array, $nested_tax_query = array(), $target_index = 0)
{

    //the first element is always the relation
    $nested_tax_query['relation'] = $array[0]['relation'];
    // unset the first element as it is not needed anymore
    unset($array[0]);


    $len = count($array);
    // reindex the array
    $array = array_values($array);


    foreach ($array as $element_key => $element) {
        if (isset($element['relation'])) {
            $target_index = $element_key;
            break;
        }
    }


    // put everything below the target index into the target index and leave the rest as it is
    for ($i = 0; $i < $len - 1; $i++) {
        if ($i < $target_index) {
            $nested_tax_query[] = $array[$i];
        } else {
            $nested_tax_query[$target_index][] = $array[$i];
        }
    }

    // last item in the nested array
    $len_nested  = count($nested_tax_query);

    // last item in the in the nested array
    $last_item_in_nested_array  = $nested_tax_query[$len_nested - 2]; 


    return $nested_tax_query;
}

我的方法正确吗？

PHP 多维数组数据结构嵌套

你是对的，递归将是一个很好的方法。首先，我建议按原样保留原始数组，这样您就不必考虑它在处理它时会经历的各种修改。要将其部分标记为已处理，可以使用索引（如参数所建议的那样）或将数组的切片传递给递归调用。target_index

我认为你已经接近了，你只需要在函数结束时对数组的其余部分（如果有更多的元素要处理）做一些事情。

$ref = [];
$result = &$ref;
foreach ($input as $row) {
    if  (key($row) !== 'relation') { // populate current level
        $ref[] = $row; // push color into reference
        continue;
    }
    if ($ref) {  // not the first relation encountered
        $ref = &$ref[];  // set $ref to point to new deeper subarray
    }
    $ref = $row; // push relation
}

var_export($result);

或者以不同的方向使用相同的逻辑：（演示)

$ref = [];
$result = &$ref;
foreach ($input as $row) {
    if (key($row) === 'relation') {
        if ($ref) {  // not the first relation encountered
            $ref = &$ref[];  // set $ref to point to new deeper subarray
        }
        $ref = $row; // push relation
    } else {
        $ref[] = $row; // push color into reference
    }
}

var_export($result);

修改 2d 数组以在遇到特定键时创建嵌套数据集

Modify 2d array to create nested datasets when specific key is encountered

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