PHP 多维和关联数组列平均值

Question

大家好我正在为 PHP 做数组，列出所有列输出并获取测试分数的平均值，但我似乎无法弄清楚获取每列平均值的逻辑.但是我不太确定我这样做是对还是错，因为我的平均输出全为 0，而且我不知道如何更改它以读取值并进行计算。

如果您能提供帮助，我们将不胜感激。谢谢。

基本上，我希望输出是这样的；-

RM = Physics : 35, Maths : 30, Chemistry : 39, English : 80,  
RM Average Scores: 46  
Justin = Physics : 61, Maths : 10, Chemistry : 45, English : 33,  
Justin Average Scores: 37.25
Miley = Physics : 25, Maths : 100, Chemistry : 88, English : 60,  
Miley Average Scores: 68.25

这是我的数组：-

<?php
 $students = array(
         "RM" => array("test1" => 35, "test2" => 30,"test3" => 39, "test4" => 80),
         "Justin" => array("test1" => 61, "test2" => 10,"test3" => 45, "test4" => 33),
         "Miley" => array("test1" => 25, "test2" => 100,"test3" => 88, "test4" => 60),
    );
?>

这是我的代码：-

<table style="border: 1px solid black">
  <?php
        
      echo "<td><p><b>Listing All Student Tests and Scores:-</b></p></td>";                  
      $the_students = array_keys($tudents);
      for($i = 0; $i < count($students); $i++) {
          echo "<tr>";
            
            // Output All Data
            echo "<td><b>". $the_students[$i] . "</b>" . " = ";
               foreach($students[$the_students[$i]] as $student => $score) {
                  echo "<b>". $student ."</b>". " : " . $score. ", ";
               }
        
          echo "<br>";
        
          // Average Output                   
          echo "<b>". $students[$i]. " Average Scores</b>: ";
          if (array_key_exists($i, $the_students)) {
              echo average_scores($students, $the_students);
          }                      
                                    
          echo "</td>";
        echo "</tr>";
      }
  ?>
</table>

我使用函数并将其放在代码的末尾：-

<?php
    function average_scores($students, $i) {
    
         $total = 0;
         $students = array();
    
         foreach ($students as $student => $data) {
                       $total += $data[$i]; 
         }
         return $total / 4;
    }
?>
   

Answer 1

既然你已经在循环了，试试这样

<table style="border: 1px solid black">
  <?php
        
      echo "<td><p><b>Listing All Student Tests and Scores:-</b></p></td>";                  
      $the_students = array_keys($tudents);
      for($i = 0; $i < count($students); $i++) {
         $total = 0;
          echo "<tr>";
            
            // Output All Data
            echo "<td><b>". $the_students[$i] . "</b>" . " = ";
               foreach($students[$the_students[$i]] as $student => $score) {
                  $total += $score;
                  echo "<b>". $student ."</b>". " : " . $score. ", ";
               }
        
          echo "<br>";
        
          // Average Output                   
          echo "<b>". $students[$i]. " Average Scores</b>: ";
          echo $total/ count($students[$the_students[$i]]);                      
                                    
          echo "</td>";
        echo "</tr>";
      }
  ?>
</table>

最好的做法是将 HTML 和 PHP 代码分开。需要时使用 PHP 标记，它将提高代码的可读性 EG：

echo "<b>". $students[$i]. " Average Scores</b>: ";
// convert to
<b><?php $students[$i]; ?> Average Scores</b>:

Answer 2

尝试foreach 循环遍历学生获取 name 这是 key 并获取 student 这是关联数组，得到只有学生的grades值并将它们分解为变量，printf 以更易读的格式打印出来。

echo '<table style="border: 1px solid black">';
echo "<tr><th>Listing All Student Tests and Scores:-</th></tr>";
foreach ($students as $name => $student) {
    $grades = array_values($student);
    [$Physics, $Maths, $Chemistry, $English] = $grades;
    echo "<tr><td>";
    printf("%s = Physics : %d, Maths : %d, Chemistry : %d, English : %d<br>
            %s Average Scores: %.2f"
            ,$name, $Physics, $Maths, $Chemistry, $English
            ,$name, average_scores($grades));
    echo "</td></tr>";
}
echo "</table>";

平均而言，您可以使用array_sum 将所有成绩相加，然后除以计数。

function average_scores($grades) {
    return array_sum($grades)/count($grades);
}