请帮忙，如何从多维数组下方显示site_id为4295, 4289, 4298, 4292的帖子，并以逗号分隔显示，如print_r($favorites);
Array
(
[0] => Array
(
[site_id] => 1
[posts] => Array
(
[0] => 4295
[1] => 4289
[2] => 4298
[3] => 4292
)
[groups] => Array
(
[0] => Array
(
[group_id] => 1
[site_id] => 1
[group_name] => Default List
[posts] => Array
(
[0] => 4295
[1] => 4289
[2] => 4298
[3] => 4292
)
)
)
)
)
c * c = a * a + b * b