php - PHPの多次元配列から配列へ

Question

私はこのような配列を持っています

$category = [
'cat1' => [
    'images/category/cat1/icon1.jpg',
    'images/category/cat1/icon2.jpg',
    'images/category/cat1/icon3.jpg',
],
'cat2' => [
    'images/category/cat2/icon1.jpg',
    'images/category/cat2/icon2.jpg',
    'images/category/cat2/icon3.jpg',
]
];

このような配列を取得したい

$categories = [
'images/category/cat1/icon1.jpg',
'images/category/cat1/icon2.jpg',
'images/category/cat1/icon3.jpg',
'images/category/cat2/icon1.jpg',
'images/category/cat2/icon2.jpg',
'images/category/cat2/icon3.jpg',
];

これを試しましたが、期待される出力が得られませんでした。

$categories = array_map(function($cat){return $cat;},$category);

Answer 1

call_user_func_array次のものと組み合わせて使用​​できますarray_merge。

$category = call_user_func_array('array_merge', $category);

Answer 2

array_reduce()&で解けるarray_merge()

$categories = array_reduce($category, function($old, $new){
    return array_merge($old, $new);
}, array());