usort php 数组/对象多维答案

【问题标题】：usort php array/object multidimensionalusort php 数组/对象多维
【发布时间】：2012-09-16 11:37:18
【问题描述】：

我无法让 php usort 工作。

我从数据库中获取这个：

Array ( [0] => stdClass Object ( [ID] => 10 [post_author] => 1 [post_date] => 2012-09-14 15:09:33 [post_date_gmt] => 2012-09-14 15:09:33 [post_content] => asdad [post_title] => geo [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => closed [post_password] => [post_name] => geo [to_ping] => [pinged] => [post_modified] => 2012-09-16 10:54:14 [post_modified_gmt] => 2012-09-16 10:54:14 [post_content_filtered] => [post_parent] => 0 [guid] => http://localhost/gold/?post_type=tribe_events&p=10 [menu_order] => 0 [post_type] => tribe_events [post_mime_type] => [comment_count] => 0 [EventStartDate] => 2012-09-19 00:00:00 [EventEndDate] => 2012-09-19 23:59:59 [filter] => raw ) [1] => stdClass Object ( [ID] => 39 [post_author] => 1 [post_date] => 2012-09-16 11:01:32 [post_date_gmt] => 2012-09-16 11:01:32 [post_content] =>
Sorry, this entry is only available in English and Russian.
[post_title] => 19 [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => 39 [to_ping] => [pinged] => [post_modified] => 2012-09-16 11:01:49 [post_modified_gmt] => 2012-09-16 11:01:49 [post_content_filtered] => [post_parent] => 0 [guid] => http://localhost/gold/?post_type=tribe_events&p=39 [menu_order] => 0 [post_type] => tribe_events [post_mime_type] => [comment_count] => 0 [EventStartDate] => 2012-09-19 08:00:00 [EventEndDate] => 2012-09-19 17:00:00 [filter] => raw ) [2] => stdClass Object ( [ID] => 37 [post_author] => 1 [post_date] => 2012-09-16 10:55:47 [post_date_gmt] => 2012-09-16 10:55:47 [post_content] => asd [post_title] => event [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => event [to_ping] => [pinged] => [post_modified] => 2012-09-16 10:55:47 [post_modified_gmt] => 2012-09-16 10:55:47 [post_content_filtered] => [post_parent] => 0 [guid] => http://localhost/gold/?post_type=tribe_events&p=37 [menu_order] => 0 [post_type] => tribe_events [post_mime_type] => [comment_count] => 1 [EventStartDate] => 2012-09-21 08:00:00 [EventEndDate] => 2012-09-21 17:00:00 [filter] => raw ) [3] => stdClass Object ( [ID] => 38 [post_author] => 1 [post_date] => 2012-09-16 10:57:01 [post_date_gmt] => 2012-09-16 10:57:01 [post_content] => asdsa [post_title] => sada [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => sada [to_ping] => [pinged] => [post_modified] => 2012-09-16 10:57:01 [post_modified_gmt] => 2012-09-16 10:57:01 [post_content_filtered] => [post_parent] => 0 [guid] => http://localhost/gold/?post_type=tribe_events&p=38 [menu_order] => 0 [post_type] => tribe_events [post_mime_type] => [comment_count] => 0 [EventStartDate] => 2012-09-27 08:00:00 [EventEndDate] => 2012-09-30 17:00:00 [filter] => raw ) [4] => stdClass Object ( [ID] => 38 [post_author] => 1 [post_date] => 2012-09-16 10:57:01 [post_date_gmt] => 2012-09-16 10:57:01 [post_content] => asdsa [post_title] => sada [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => sada [to_ping] => [pinged] => [post_modified] => 2012-09-16 10:57:01 [post_modified_gmt] => 2012-09-16 10:57:01 [post_content_filtered] => [post_parent] => 0 [guid] => http://localhost/gold/?post_type=tribe_events&p=38 [menu_order] => 0 [post_type] => tribe_events [post_mime_type] => [comment_count] => 0 [EventStartDate] => 2012-09-28 08:00:00 [EventEndDate] => 2012-10-01 17:00:00 [filter] => raw ) [5] => stdClass Object ( [ID] => 38 [post_author] => 1 [post_date] => 2012-09-16 10:57:01 [post_date_gmt] => 2012-09-16 10:57:01 [post_content] => asdsa [post_title] => sada [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => sada [to_ping] => [pinged] => [post_modified] => 2012-09-16 10:57:01 [post_modified_gmt] => 2012-09-16 10:57:01 [post_content_filtered] => [post_parent] => 0 [guid] => http://localhost/gold/?post_type=tribe_events&p=38 [menu_order] => 0 [post_type] => tribe_events [post_mime_type] => [comment_count] => 0 [EventStartDate] => 2012-09-29 08:00:00 [EventEndDate] => 2012-10-02 17:00:00 [filter] => raw ) [6] => stdClass Object ( [ID] => 38 [post_author] => 1 [post_date] => 2012-09-16 10:57:01 [post_date_gmt] => 2012-09-16 10:57:01 [post_content] => asdsa [post_title] => sada [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => sada [to_ping] => [pinged] => [post_modified] => 2012-09-16 10:57:01 [post_modified_gmt] => 2012-09-16 10:57:01 [post_content_filtered] => [post_parent] => 0 [guid] => http://localhost/gold/?post_type=tribe_events&p=38 [menu_order] => 0 [post_type] => tribe_events [post_mime_type] => [comment_count] => 0 [EventStartDate] => 2012-09-30 08:00:00 [EventEndDate] => 2012-10-03 17:00:00 [filter] => raw ) )

我想使用 usort 和 comment_count 对象来订购。我试过这个（但显然是错误的）：

function sortByComments($a, $b) {
    return ($a[0]->comment_count) - ($b[0]->comment_count);
}

$sorted_by_comments_array = usort($all_events, 'sortByComments');

错误：Cannot use object of type stdClass as array

【问题讨论】：

你可以在你的sql语句中做到这一点，你也可以提供吗？
@KorvinSzanto 这不会比sql语句快吗？
不，您已经在运行 sql 语句，当 sql 已经在压缩时对其进行排序时，对大量未压缩数组进行排序并不会更快。
@KorvinSzanto 我正在使用 wordpress wp_quer 函数，所以不直接运行 sql 查询。即使在这种情况下，直接运行sql查询而不是使用wp hook更好吗？顺便说一句，回答我的问题，我真的对学习有效的方法很感兴趣。
查看documentation for WP_Query 中的orderby。 @KorvinSzanto 是正确的，它在查询中执行此操作更快，而不是在 PHP 中对输出进行排序。

标签： php usort

【解决方案1】：

我发现读取数组的结构有点困难，但我认为数组的元素是您要排序的对象是正确的。这意味着$a 和$b 本身就是您需要排序的对象。

因此，这意味着您无需以 $a[0]->comment_count 的身份访问它们，而只需以 $a->comment_count 的身份访问它们：

function sortByComments($a, $b) {
    return $a->comment_count - $b->comment_count;
}

（请注意，括号也是不必要的。）

【讨论】：

成功了！但是我将如何颠倒顺序？现在它订购了 0 1，我想订购 1, 0 comment_count。
return $b->comment_count - $a->comment_count; 将颠倒顺序。
我也可以这样做吗？返回 $a->comment_count comment_count;
@SandroDzneladze 不，因为它想要一个三进制而不是二进制：“$a 比 $b 低、更高还是一样？”