php - 从数组中删除重复值

我有一个看起来像-

Array
(
    [0] => stdClass Object
    (
        [post_date] => 2017-01-04 14:28:00
    )

    [1] => stdClass Object
    (
        [post_date] => 2017-01-05 11:06:00
    )

    [2] => stdClass Object
    (
        [post_date] => 2017-02-04 14:28:00
    )

    [3] => stdClass Object
    (
        [post_date] => 2017-02-04 14:34:00
    )
)

我使用substr（）函数来获取特定的部分-

foreach($unique_dates as $val) {
    $year=substr($val->post_date,0,4);
    $month=substr($val->post_date,5,2);
    $monthName = date('F', mktime(0, 0, 0, $month, 10));
    echo $monthName." ".$year."<br>";
}

现在它显示输出如下-

January 2017
January 2017
February 2017
February 2017

但我希望输出像-

 January 2017
February 2017

我试了如下方法，但没有得到正确的结果-

$unique_dates = array_map(
                    'unserialize',
                     array_unique(
                         array_map(
                             'serialize',
                             $dates
                         )
                     )
                );

我要删除重复值。
这怎么可能？
谢谢。

最佳答案

像这样运行：

foreach($unique_dates as $val) {
    $year=substr($val->post_date,0,4);
    $month=substr($val->post_date,5,2);
    $monthName = date('F', mktime(0, 0, 0, $month, 10));
    $result[] = $monthName." ".$year;
}
$result = array_flip($result); // here will remove the duplicate value, and return as the keys of the array.
array_walk($results, function($v, $k){echo $k.'<br>';});