将对象数组减少到 'best 10'

Question

我有一组对象，它们是足球运动员。该数组可以包含从零到数千名玩家的任何内容。我想将它减少到最好的 10。我最初的尝试如下：

while (count($ArrayOfPlayers) > 10) {

    $ArrayIndex = 0;
    $WorstPlayerIndex = -1;
    $WorstPlayerSkill = 9999999999;
    foreach ($ArrayOfPlayers as $Player) {
        $Skill = $Player->RatingsArray['Skill'];
        if ($Skill < $WorstPlayerSkill) {
            $WorstPlayerIndex = $ArrayIndex;
            $WorstPlayerSkill = $Skill;
        }
        $ArrayIndex += 1;
    }

    // Found the worst player in the list, so remove him.
    unset($ArrayOfPlayers[$WorstPlayerIndex]);
}

通读了类似的帖子后，我现在知道问题是数组实际上并没有被更改，所以 while 循环一直持续下去（计算机确实锁定了）。

因此，根据其他帖子的建议，我尝试进行如下更正。

while (count($ArrayOfPlayers) > 10) {

        $WorstIndexPlayer = 0;
        $WorstPlayerSkill = 9999999999;
        foreach ($ArrayOfPlayers as $key => &$Player) {
            $Skill = $Player->RatingsArray['Skill'];
            if ($Skill < $WorstPlayerSkill) {
                $WorstIndexPlayer = $key;
                $WorstPlayerSkill = $Skill;
            }
        }
        // Found the worst player in the list, so remove him.
        unset($ArrayOfPlayers[$WorstIndexPlayer]);
}

你可能会说，我不明白我现在在做什么，也不明白 $key 部分是干什么用的（它只是从其他示例中复制过来的）。它仍然只是挂起 PC。

我该如何更正这个问题，或者是否有更好的方法来实现这一点？

为了响应对数据结构的请求，这里仅转储 2 个玩家以显示他们的排列方式。

Array
(
[0] => Player Object
    (
        [ID] => 1
        [TeamID] => 1
        [Name] => Joseph Dorrington
        [RatingsArray] => Array
            (
                [Skill] => 51993
            )
    )

[1] => Player Object
    (
        [ID] => 2
        [TeamID] => 1
        [Name] => Oliver Tillyard
        [RatingsArray] => Array
            (
                [Skill] => 64574
            )

    )

Answer 1

使用usort，你可以先根据这个值对数组进行排序，然后，使用array_slice，取前10个元素：

function cmp($a, $b){
    if ($a->RatingsArray['Skill'] == $b->RatingsArray['Skill']) {
        return 0;
    }
    return ($a->RatingsArray['Skill'] > $b->RatingsArray['Skill']) ? -1 : 1;
}
usort($ArrayOfPlayers, "cmp");
$ArrayOfPlayers = array_slice($ArrayOfPlayers, 0, 10);

Answer 2

我在想可能有更简单的方法。

我们按技能水平（降序）排序，然后 "slice" 前 10 个代表最好的方法怎么样？

假设您的结构如下所示：

$arrayOfPlayers = array (size=6)
0 => 
    object(stdClass)[1]
      public 'RatingsArray' => 
        array (size=1)
          'Skill' => int 1187
  1 => 
    object(stdClass)[2]
      public 'RatingsArray' => 
        array (size=1)
          'Skill' => int 44
  2 => 
    object(stdClass)[3]
      public 'RatingsArray' => 
        array (size=1)
          'Skill' => int 494
  3 => 
    object(stdClass)[4]
      public 'RatingsArray' => 
        array (size=1)
          'Skill' => int 584
  4 => 
    object(stdClass)[5]
      public 'RatingsArray' => 
        array (size=1)
          'Skill' => int 730
  5 => 
    object(stdClass)[6]
      public 'RatingsArray' => 
        array (size=1)
          'Skill' => int 613
 ...

下面的代码可以为您做到这一点：

// Call our custom usort function
usort($arrayOfPlayers, 'sort_players');
// Slice the array to the best 10.  Note array_slice doesn't care if there's less than 10
$best = array_slice($arrayOfPlayers, 0, 10);

// Our custom sorting function
function sort_players($a, $b) {
    if ($a->RatingsArray['Skill'] == $b->RatingsArray['Skill']) {
        return 0;
    }

    return ($a->RatingsArray['Skill'] < $b->RatingsArray['Skill']) ? 1: -1;
}

将对象数组减少到 'best 10'

Reduce an array of objects to the 'best 10'

php

arrays

loops

foreach

unset