PHP array_merge_recursive与foreach循环

Question

如何将数组循环合并到单个数组（可能是对象）中，将每个值添加到与其关联的公共键中？

Categories: 

Array ( [category] => introduction [timeZone] => Europe/Stockholm [language] => Danish )

Array ( [category] => introduction [timeZone] => Europe/Stockholm [language] => Danish )

Array ( [category] => e-learning [timeZone] => Europe/Stockholm [language] => German )

成

Collection

Array ( 
        [category] => Array (e-learning,introduction) 
        [timeZone] => Europe/Stockholm 
        [language] => Array (Danish,German)
)

到目前为止的Mycode：

foreach ($categories as $category){
   $collection = array_merge_recursive($category);
}

如果在PHP中将$ array1，$ array2分隔开，array_merge_recursive似乎可以达到我的结果。 但是我需要从一个foreach循环开始。

谢谢。

Answer 1

给定名为$categories的初始数组，请考虑：

$collection = array_merge_recursive(...$categories);
foreach($collection as &$item) $item = array_unique($item);

输出：

[
  'category' => ['intro','learning'],
  'timezone' => ['Europe'],
  'language' => ['Danish','German'],
]

现场演示

Answer 2

我想这个棘手的解决方案：

$collection = [];
// get keys of a first element of categories
$keys = array_keys($categories[0]);
// iterate over these keys
foreach ($keys as $key) {
    // use `array_unique` to eliminate duplicates
    $collection[] = array_unique(
        // `array_column` will give you all values under `$key`
        array_column($categories, $key)
    );
}

当然，此功能自php5.5起生效，因为在此版本中，我们具有array_column 。