如何在PHP中重新刪除多維數組中的重複值

Question

如何從PHP中的多維數組中刪除重複值？

初始陣列：

array (
    0 => 
    array (
    'following_userid' => '88', 
), 
    1 => 
    array (
    'following_userid' => '89', 
), 
    2 => 
    array (
    'following_userid' => '287', 
), 
    3 => 
    array (
    'following_userid' => '346', 
), 
    4 => 
    array (
    'following_userid' => '405', 
), 
    5 => 
    array (
    'following_userid' => '284', 
), 
    6 => 
    array (
    'following_userid' => '583', 
), 
    7 => 
    array (
    'following_userid' => '587', 
), 
    8 => 
    array (
    'following_userid' => '655', 
), 
    9 => 
    array (
    'following_userid' => '95', 
), 
    10 => 
    array (
    'follower_userid' => '89', 
), 
    11 => 
    array (
    'follower_userid' => '88', 
), 
    12 => 
    array (
    'follower_userid' => '353', 
), 
    13 => 
    array (
    'follower_userid' => '42', 
), 
    14 => 
    array (
    'follower_userid' => '626', 
), 
    15 => 
    array (
    'follower_userid' => '655', 
), 
    16 => 
    array (
    'follower_userid' => '95', 
), 
) 

作爲每How to remove duplicate values from a multi-dimensional array in PHP建議我用$input = array_map("unserialize", array_unique(array_map("serialize", $input)));

Array，執行array_unique()後：

array (
    0 => 
    array (
    'following_userid' => '88', 
), 
    1 => 
    array (
    'following_userid' => '89', 
), 
    2 => 
    array (
    'following_userid' => '287', 
), 
    3 => 
    array (
    'following_userid' => '346', 
), 
    4 => 
    array (
    'following_userid' => '405', 
), 
    5 => 
    array (
    'following_userid' => '284', 
), 
    6 => 
    array (
    'following_userid' => '583', 
), 
    7 => 
    array (
    'following_userid' => '587', 
), 
    8 => 
    array (
    'following_userid' => '655', 
), 
    9 => 
    array (
    'following_userid' => '95', 
), 
    10 => 
    array (
    'follower_userid' => '89', 
), 
    11 => 
    array (
    'follower_userid' => '88', 
), 
    12 => 
    array (
    'follower_userid' => '353', 
), 
    13 => 
    array (
    'follower_userid' => '42', 
), 
    14 => 
    array (
    'follower_userid' => '626', 
), 
    15 => 
    array (
    'follower_userid' => '655', 
), 
    16 => 
    array (
    'follower_userid' => '95', 
), 
) 

但是仍然得到重複的答案。似乎對原始數組沒有影響。

Answer 1

首先，因爲5.2.9可以使用更簡單的版本，從this answer採取：

array_unique($array, SORT_REGULAR); 

在這種情況下，實際上array_unique()給出正確的輸出;這裏的事情是，你有兩個不同的密鑰數組中：「跟隨 _userid」和「下 _userid 」，因此要獲得的唯一ID的不管是鑰匙，你必須首先正常化它：

array_map('current', $array); 

這樣做需要每個數組的第一個元素，並使用該第一個元素的值創建一個新數組。

輸出：

Array 
(
    [0] => 88 
    [1] => 89 
    [2] => 287 
    [3] => 346 
    [4] => 405 
    [5] => 284 
    [6] => 583 
    [7] => 587 
    [8] => 655 
    [9] => 95 
    [10] => 89 
    [11] => 88 
    [12] => 353 
    [13] => 42 
    [14] => 626 
    [15] => 655 
    [16] => 95 
); 

，然後應用array_unique()：

array_unique(array_map('current', $array)); 

Answer 2

如果它總是隻會剛纔的follower_userid，你可以只拼合陣列下來是這樣的：

$followers = array(); 
foreach ($input as $item) { 
    $followers[] = $item['followers_userid']; 
} 

$followers = array_unique($followers);