构建“交叉表” 或“枢轴” php 中数组中的表

Question

我有一个类似于以下定义的对象数组：

$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有多少玩家，只能说我无法改变对象的构造方式。

在 php 中执行此操作最有效的方法是什么？

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）

Answer 2

如果我们可以假设：

• 数组中分数的顺序始终按照玩家姓名的顺序
  然后根据轮数，
• 每个玩家的轮数相同

然后，我们可以做的是在遍历数组时打印每个玩家的得分，同时计算过程中的总数，但如果我们看到新玩家则重置它：

$round_count = 0;
$header_printed = false;
$current_player = NULL;
$current_total = 0;
$current_output_line = "";
foreach ($scores as $score) {
    // Check whether we have to move to a new player
    if ($score->Player_Name != $current_player) {
        // Check whether we have anything to print before
        // resetting the variables
        if (!is_null($current_player)) {
            if (!$header_printed) {
                printf("%-10s", "Player");
                for ($i = 0; $i < $round_count; $i++) {
                    printf("%-10s", "Round $i");
                }
                printf("%-10s\n", "Total");

                $header_printed = true;
            }

            $current_output_line .= sprintf("%5d\n", $current_total);
            print $current_output_line;
        }

        // Reset the total and various variables for the new player
        $round_count = 0;
        $current_player = $score->Player_Name;
        $current_total = 0;
        $current_output_line = sprintf("%-10s", $score->Player_Name);
    }

    $round_count++;
    $current_total += $score->Score;
    $current_output_line .= sprintf("%5d     ", $score->Score);
}
// The last player is not printed because we exited the loop 
// before the print statement, so we need a print statement here.
if ($current_output_line != "") {
    $current_output_line .= sprintf("%5d\n", $current_total);
    print $current_output_line;
}

示例输出：

Player    Round 0   Round 1   Total
Bob          10         7        17
Jack          6        12        18

这应该非常有效，因为它只遍历数组一次。