在PHP while循环中获取某一行的相邻行(上面2行，下面2行)

<?php
// 假设有一个包含多行数据的数组
$data = array(
    "行1",
    "行2",
    "行3",
    "行4",
    "行5",
    // ...
);

// 循环遍历数组
foreach ($data as $key => $value) {
    // 获取当前行的索引
    $currentIndex = $key;

    // 获取上面2行的索引
    $previousIndex1 = $currentIndex - 1;
    $previousIndex2 = $currentIndex - 2;

    // 获取下面2行的索引
    $nextIndex1 = $currentIndex + 1;
    $nextIndex2 = $currentIndex + 2;

    // 检查上面2行是否存在
    if (isset($data[$previousIndex1]) && isset($data[$previousIndex2])) {
        $previousLine1 = $data[$previousIndex1];
        $previousLine2 = $data[$previousIndex2];
        echo "上面2行：$previousLine1, $previousLine2\n";
    }

    // 检查下面2行是否存在
    if (isset($data[$nextIndex1]) && isset($data[$nextIndex2])) {
        $nextLine1 = $data[$nextIndex1];
        $nextLine2 = $data[$nextIndex2];
        echo "下面2行：$nextLine1, $nextLine2\n";
    }
}
?>