在php中从数组构建"交叉表"或"数据透视表"

Question

我有一个与下面类似的对象数组:

$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;

如果我循环并将$scores对象转储到表中,它将看起来像这样:

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

然而,我想要的是这样的:

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

我不会提前知道会有多少轮或球员,让我们说我无法改变对象的构造方式.

什么是在PHP中最有效的方法？

Answer 1

据我所知,PHP数组实现为哈希表(因此查找/更新应该非常有效)无论如何,时间效率甚至会成为问题吗？

我会以"简单"的方式做到这一点:

$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)