php - 获取多维数组中每个唯一键的最大值

Question

我有一个类似于下面的数组。我正在尝试获取数组中每个唯一键的最大权重值，例如 Store A = 230、Store B = 180、Store C = 439，对于品牌键也是如此。

Array ( 
[0] => Array ( [cid] => 123 [weight] => 230 [store] => Store A [brand] => Brand A)
[1] => Array ( [cid] => 124 [weight] => 180 [store] => Store B [brand] => Brand B ) 
[2] => Array ( [cid] => 131 [weight] => 439 [store] => Store C [brand] => Brand B ) 
[3] => Array ( [cid] => 128 [weight] => 124 [store] => Store B [brand] => Brand B ) 
[4] => Array ( [cid] => 130 [weight] => 249 [store] => Store C [brand] => Brand C ) 
)

我可以获得整个数组的最大权重值（使用 max()，但需要每个相应键的最大权重。已经搞砸了几个小时，却没有得到任何地方！

任何指针将不胜感激。

Answer 1

$array = $array() // Your array
$max = array();

foreach ( $array as $product) {
    if ( ! isset( $max[ $product['store'] ] ) ) {
        $max[ $product['store'] ] = $product['weight'];
    } else {
        $max[ $product['store'] ] = max( $max[ $product['store'] ], $product['weight'] );
    }
}

在此处查看实际操作：http ://codepad.viper-7.com/eF4ZQ7

Answer 2

$maxes = array();

foreach ($array as $i) {
    if (!isset($maxes[$i['store']]) || $maxes[$i['store']] < $i['weight']) {
        $maxes[$i['store']] = $i['weight'];
    }
}

var_dump($maxes);