PHP 数组中子键的平均值答案

【问题标题】：PHP Average of subkeys in an arrayPHP 数组中子键的平均值
【发布时间】：2014-08-05 00:24:27
【问题描述】：

Array (
  [JohnDoe] => Array (
  [id] => 23
  [name] => JohnDoe
  [logintimes] => 30
)
 [JaneDoe] => Array (
  [id] => 26
  [name] => JaneDoe
  [logintimes] => 9
)
 [Smith] => Array (
  [id] => 35
  [name] => Smith
  [logintimes] => 9
 )
)

如何将登录时间相加（然后找到它们的平均值？）

【问题讨论】：

标签： php arrays associative-array

【解决方案1】：

很容易循环并得到它

$counter = 0;
$total = 0;
foreach($array as $row) {
    $counter++;
    $total += $row['logintimes'];
}
echo $total / $counter;

【讨论】：

【解决方案2】：

您也可以使用array_sum 和array_map 来做到这一点：

$sum = array_sum(array_map(function($item) { 
    return $item['logintimes']; 
}, $your_array));

echo $sum / count ($your_array);

【讨论】：

【解决方案3】：

为了完整起见，PHP >= 5.5.0：

$average = array_sum(array_column($array, 'logintimes')) / count($array);

【讨论】：

【解决方案4】：

您必须遍历数组，并使用子数组引用来合计 logintimes 值。完成后，您只需将 logintimes 的总数除以数组项的数量即可。

示例：

<?php
$users = array(
    "JohnDoe" => array(
        "id" => 23,
        "name" => "JohnDoe",
        "logintimes" => 30
    ),
    "JaneDoe" => array(
        "id" => 23,
        "name" => "JaneDoe",
        "logintimes" => 9
    ),
    "Smith" => array(
        "id" => 35,
        "name" => "Smith",
        "logintimes" => 9
    )
);

$count = 0;
$total = 0;
foreach($users as $user => $values) {
    $count++;
    $total += $values['logintimes'];
}
$average = $total / $count;

echo $average;  //Output 16

工作示例：http://codepad.org/uHpJnODv

【讨论】：

【解决方案5】：

认为这个解决方案应该更高效（PHP 5.5+）：

 <?php
$users = array(
    "JohnDoe" => array(
        "id" => 23,
        "name" => "JohnDoe",
        "logintimes" => 30
    ),
    "JaneDoe" => array(
        "id" => 23,
        "name" => "JaneDoe",
        "logintimes" => 9
    ),
    "Smith" => array(
        "id" => 35,
        "name" => "Smith",
        "logintimes" => 9
    )
);

$count = count($users);
$average = array_column($users , 'logintimes') / $count;

echo $average;  //Output 16

【讨论】：