php - 从 php 中的数组构建 "crosstab"或 "pivot"表

Question

我有一个类似于下面定义的对象数组:

$scores = array();

// Bob round 1
$s = new RoundScore();
$s->Round_Name = 'Round 1';
$s->Player_Name = 'Bob';
$s->Score = 10;
$scores[0] = $s;

// Bob round 2
$s = new RoundScore();
$s->Round_Name = 'Round 2';
$s->Player_Name = 'Bob';
$s->Score = 7;
$scores[1] = $s;

// Jack round 1
$s = new RoundScore();
$s->Round_Name = 'Round 1';
$s->Player_Name = 'Jack';
$s->Score = 6;
$scores[2] = $s;

// Jack round 2
$s = new RoundScore();
$s->Round_Name = 'Round 2';
$s->Player_Name = 'Jack';
$s->Score = 12;
$scores[3] = $s;

如果我遍历并将 $scores 对象转储到一个表中，它将看起来像这样:

Round_Name   Player   Score----------------------------Round 1      Bob        10Round 2      Bob         7Round 1      Jack        6Round 2      Jack       12

然而，我想要的是这样的:

Player  Round 1  Round 2  Total-------------------------------Bob       10        7       17Jack       6       12       18

我不会提前知道会有多少轮或玩家，我只能说我无法改变对象的构建方式。

在 php 中执行此操作的最有效方法是什么？

Answer 1

据我所知，PHP 数组是作为哈希表实现的(因此查找/更新应该非常有效)无论如何，时间效率会成为问题吗？

我会用“简单”的方式来做:

$table = array();
$round_names = array();
$total = array();

foreach ($scores as $score)
{
    $round_names[] = $score->Round_Name;
    $table[$score->Player_Name][$score->Round_Name] = $score->score;
    $total[$score->Player_Name] += $score->score;
}

$round_names = array_unique($round_names);

foreach ($table as $player => $rounds)
{
    echo "$player\t";
    foreach ($round_names as $round)
        echo "$rounds[$round]\t";
    echo "$total[$player]\n";
}

(我知道数组没有正确初始化，但你明白了)