PHP - 循环遍历数组并仅在迭代之间发生变化时才打印出值

Question

如果有人问过这个问题，但我找不到满足我需求的解决方案，我深表歉意。我在 PHP 7 应用程序中有一个数组，如下所示：$data = [    0 => [        'regulations_label' => 'Europe',        'groups_label' => 'G1',        'filters_label' => 'FF1'    ],    1 => [        'regulations_label' => 'Europe',        'groups_label' => 'G1',        'filters_label' => 'FF900'    ],    2 => [        'regulations_label' => 'Europe',        'groups_label' => 'G1',        'filters_label' => 'FF324234'    ],    3 => [        'regulations_label' => 'Europe',        'groups_label' => 'G2',        'filters_label' => 'FF23942'    ],    4 => [        'regulations_label' => 'America',        'groups_label' => 'G29',        'filters_label' => 'FF3242'    ],    5 => [        'regulations_label' => 'America',        'groups_label' => 'G29',        'filters_label' => 'FF78978'    ],    6 => [        'regulations_label' => 'America',        'groups_label' => 'G29',        'filters_label' => 'FF48395043'    ],    7 => [        'regulations_label' => 'Asia',        'groups_label' => 'G2000',        'filters_label' => 'FF7'    ],    // ...];我想要实现的输出是这样的：Europe    - G1        -- FF1        -- FF900    - G2        -- FF23942America    - G29        -- FF3242        -- FF48395043Asia    - G2000        -- FF7本质上，它所做的就是以结构化格式输出数组，以便它显示regulations_label后跟任何对应的groups_label，然后是任何filters_label。遍历整个数组很简单，例如foreach ($data as $d) {    echo $d['regulations_label'] . "\n";    echo ' - ' . $d['groups_label'] . "\n";    echo ' -- ' . $d['filters_label'] . "\n";}然而，这引入了“重复”标题regulations_label，groups_label因为它正在打印每个键。但是我不知道如何检查这在foreach语句期间是否已更改，因为$d它始终是当前元素。我试图根据以前的数组键进行检查：foreach ($data as $key => $d) {   if ($data[$key-1]['regulations_label'] !== $d['regulations_label']) {       echo $d['regulations_label'] . "\n";       echo "-" . $d['groups_label'] . "\n";   }}麻烦的是，这然后只打印 1groups_label所以我最终会得到 - 例如：Europe- G1America...它不会达到“G2”。我不禁觉得我在用一种奇怪的方式来处理这个问题。谁能建议一个更好的解决方案？

Answer 1

您可以使用foreach通过使用组regulations_label和groups_label

$group = [];

foreach($data as $v){

  $group[$v['regulations_label']][$v['groups_label']][] = $v['filters_label'];

}

Answer 2

您需要做的就是记住上次处理的内容，然后添加几个 IF

$data = [

    0 => ['regulations_label' => 'Europe','groups_label' => 'G1','filters_label' => 'FF1'],

    1 => ['regulations_label' => 'Europe','groups_label' => 'G1','filters_label' => 'FF900'],

    2 => ['regulations_label' => 'Europe','groups_label' => 'G1','filters_label' => 'FF324234'],

    3 => ['regulations_label' => 'Europe','groups_label' => 'G2','filters_label' => 'FF23942'],

    4 => ['regulations_label' => 'America','groups_label' => 'G29','filters_label' => 'FF3242'],

    5 => ['regulations_label' => 'America','groups_label' => 'G29','filters_label' => 'FF78978'],

    6 => ['regulations_label' => 'America','groups_label' => 'G29','filters_label' => 'FF48395043'],

    7 => ['regulations_label' => 'Asia','groups_label' => 'G2000','filters_label' => 'FF7']

];

$last_reg = NULL;

$last_grp = NULL;

foreach ($data as $reg) {

    if ( $last_reg != $reg['regulations_label']) {

        echo $reg['regulations_label'] . "\n";

        $last_reg = $reg['regulations_label'];

        $last_grp = NULL;

        $last_filter = NULL;

    }

    if ( $last_grp != $reg['groups_label']) {

        echo "\t - " . $reg['groups_label'] . "\n";

        $last_grp = $reg['groups_label'];

    }

    echo "\t\t - " . $reg['filters_label'] . "\n";

}

结果：

Europe

     - G1

         - FF1

         - FF900

         - FF324234

     - G2

         - FF23942

America

     - G29

         - FF3242

         - FF78978

         - FF48395043

Asia

     - G2000

         - FF7