PHP实现同color键下val、val1、val2字段求和的最优方案

给定如下PHP数组，需要按color字段分组，将每组内的val、val1、val2字段分别求和：

$originalArray = [
    ['color' => 'red', 'val' => 4, 'val1' => 4, 'val2' => 4],
    ['color' => 'green', 'val' => 3, 'val1' => 3, 'val2' => 3],
    ['color' => 'blue', 'val' => 1, 'val1' => 3, 'val2' => 3],
    ['color' => 'green', 'val' => 6, 'val1' => 3, 'val2' => 3],
    ['color' => 'blue', 'val' => 2, 'val1' => 3, 'val2' => 3],
];

期望得到的结果：

Array
(
    [0] => Array
        (
            [color] => red
            [val] => 4
            [val1] => 4
            [val2] => 4
        )

    [1] => Array
        (
            [color] => green
            [val] => 9
            [val1] => 6
            [val2] => 6
        )

    [2] => Array
        (
            [color] => blue
            [val] => 3
            [val1] => 6
            [val2] => 6
        )
)

最优解法：一次遍历累加 #

最高效且易维护的方式是通过单次遍历原数组，以color为键维护结果数组，逐步累加对应字段值，时间复杂度仅为O(n)（n为原数组元素数量）：

<?php
$originalArray = [
    ['color' => 'red', 'val' => 4, 'val1' => 4, 'val2' => 4],
    ['color' => 'green', 'val' => 3, 'val1' => 3, 'val2' => 3],
    ['color' => 'blue', 'val' => 1, 'val1' => 3, 'val2' => 3],
    ['color' => 'green', 'val' => 6, 'val1' => 3, 'val2' => 3],
    ['color' => 'blue', 'val' => 2, 'val1' => 3, 'val2' => 3],
];

$result = [];
foreach ($originalArray as $item) {
    $color = $item['color'];
    // 初始化当前color的统计项（首次出现时）
    if (!isset($result[$color])) {
        $result[$color] = [
            'color' => $color,
            'val' => 0,
            'val1' => 0,
            'val2' => 0,
        ];
    }
    // 累加对应字段值
    $result[$color]['val'] += $item['val'];
    $result[$color]['val1'] += $item['val1'];
    $result[$color]['val2'] += $item['val2'];
}

// 若需要将关联数组转为索引数组，去掉color作为键名
$result = array_values($result);

print_r($result);
?>

解法说明 #

• 遍历过程中，用color作为结果数组的键，避免重复分组判断；
• 首次遇到某个color时，初始化其统计结构；
• 后续遇到同color的元素，直接累加对应字段值；
• 最后通过array_values()将结果转为索引数组，匹配期望输出格式。

内容的提问来源于stack exchange，提问作者arunfrancis