PHP中关联数组键名保留的随机化与切片操作

<?php
$speciesarray = array(
    "Amanita aprica" => "species/Amanita_aprica.html",
    "Amanita augusta" => "species/Amanita_augusta.html",
    // ... 更多元素
    "Amanita velosa" => "species/Amanita_velosa.html"
);

shuffle($speciesarray); // 随机排序数组
print_r($speciesarray);
?>

Array ( [0] => species/Amanita_velosa.html [1] => species/Amanita_aprica.html ... )

<?php
$data = array(
    "key1" => "value1",
    "key2" => "value2",
    "key3" => "value3"
);

$sliced_default = array_slice($data, 0, 2); // 默认行为，重置键名
print_r($sliced_default);

$sliced_preserved = array_slice($data, 0, 2, true); // 保留键名
print_r($sliced_preserved);
?>

Array ( [0] => value1 [1] => value2 ) // 默认切片
Array ( [key1] => value1 [key2] => value2 ) // 保留键名切片

<?php
/**
 * 随机打乱关联数组，并保留其键名。
 *
 * @param array $array 待打乱的关联数组，通过引用传递。
 * @return bool 总是返回 true。
 */
function shuffle_assoc(&$array) {
    $keys = array_keys($array); // 获取数组的所有键
    shuffle($keys); // 随机打乱键的顺序

    $new_array = [];
    foreach ($keys as $key) {
        $new_array[$key] = $array[$key]; // 按照新的键顺序构建新数组
    }

    $array = $new_array; // 将原数组替换为新数组
    return true;
}
?>

<?php
/**
 * 随机打乱关联数组，并保留其键名。
 *
 * @param array $array 待打乱的关联数组，通过引用传递。
 * @return bool 总是返回 true。
 */
function shuffle_assoc(&$array) {
    $keys = array_keys($array);
    shuffle($keys);

    $new_array = [];
    foreach ($keys as $key) {
        $new_array[$key] = $array[$key];
    }

    $array = $new_array;
    return true;
}

$speciesarray = array(
    "Amanita aprica" => "species/Amanita_aprica.html",
    "Amanita augusta" => "species/Amanita_augusta.html",
    "Amanita calyptratoides" => "species/Amanita_calyptratoides.html",
    "Amanita calyptroderma" => "species/Amanita_calyptroderma.html",
    "Amanita constricta" => "species/Amanita_constricta.html",
    "Amanita gemmata" => "species/Amanita_gemmata.html",
    "Amanita magniverrucata" => "species/Amanita_magniverrucata.html",
    "Amanita muscaria" => "species/Amanita_muscaria.html",
    "Amanita novinupta" => "species/Amanita_novinupta.html",
    "Amanita ocreata" => "species/Amanita_ocreata.html",
    "Amanita pachycolea" => "species/Amanita_pachycolea.html",
    "Amanita pantherina" => "species/Amanita_pantherina.html",
    "Amanita phalloides" => "species/Amanita_phalloides.html",
    "Amanita porphyria" => "species/Amanita_porphyria.html",
    "Amanita protecta" => "species/Amanita_protecta.html",
    "Amanita pruittii" => "species/Amanita_pruittii.html",
    "Amanita silvicola" => "species/Amanita_silvicola.html",
    "Amanita smithiana" => "species/Amanita_smithiana.html",
    "Amanita vaginata" => "species/Amanita_vaginata.html",
    "Amanita velosa" => "species/Amanita_velosa.html",
    "Amanita vernicoccora" => "species/Amanita_vernicoccora.html"
);

shuffle_assoc($speciesarray); // 使用自定义函数随机打乱并保留键名

// 从打乱后的数组中选择前5个元素，并保留键名
$selected_species = array_slice($speciesarray, 0, 5, true); 

reset($selected_species); // 将数组内部指针重置到第一个元素
$choice = key($selected_species); // 获取第一个元素的键名

// 再次随机打乱选定的5个元素（如果需要），同样需要保留键名
shuffle_assoc($selected_species);

/* 用于调试 */
echo "选定的物种数组：<br/>";
print_r($selected_species);
echo("<br/>");
echo "第一个物种的键名：<br/>";
print_r($choice);
?>

选定的物种数组：
Array ( [Amanita silvicola] => species/Amanita_silvicola.html [Amanita gemmata] => species/Amanita_gemmata.html [Amanita calyptratoides] => species/Amanita_calyptratoides.html [Amanita vaginata] => species/Amanita_vaginata.html [Amanita phalloides] => species/Amanita_phalloides.html )
第一个物种的键名：
Amanita silvicola