php – 从数组中删除重复值

我有一个看起来像的数组 –

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

现在它显示输出像 –

January 2017  
January 2017  
February 2017  
February 2017

但是我希望输出像 –

January 2017  
February 2017

我尝试如下但没有得到适当的输出 –

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

我想删除重复值.
这怎么可能？
谢谢.

解决方法

像这样运行：

foreach($unique_dates as $val) { 
    $year=substr($val->post_date,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>';});