从多维数组中获取多个最大键与值的数组

Question

我有一个多维数组如下：

$data = ['data' => [
     'tree1' => ['fruits' => 20],
     'tree2' => ['fruits' => 15],
     'tree3' => ['fruits' => 20],
     'tree4' => ['fruits' => 17]
]];

如何获得具有最大fruits 值的数组，其键和值如下：

array(
    'tree1' => 20,
    'tree3' => 20,
)

目前我正在使用自定义循环和If Else 语句提取此数组。

有没有更好的方法来使用 PHP 提取这样的数组？

Answer 1

一种方法是计算最大fruits 值（这可以使用array_column 来提取值）然后遍历数组，当水果为最大值时推送键/水果对：

$data = ['data' => [
     'tree1' => ['fruits' => 20],
     'tree2' => ['fruits' => 15],
     'tree3' => ['fruits' => 20],
     'tree4' => ['fruits' => 17]
]];

$max_fruit = max(array_column($data['data'], 'fruits'));

$output = array();
foreach ($data['data'] as $key => $value) {
    if ($value['fruits'] == $max_fruit) {
        $output[$key] = $max_fruit;
    }
}
print_r($output);

输出

Array
(
    [tree1] => 20
    [tree3] => 20
)

Demo on 3v4l.org

对于$data 具有多组具有不同键的树数据的情况，您需要遍历每组数据，首先生成$max_fruit 值（array_map 对此很有用），然后使用嵌套的foreach 来获取匹配值：

$data = ['data1' => [
     'tree1' => ['fruits' => 20],
     'tree2' => ['fruits' => 15],
     'tree3' => ['fruits' => 20],
     'tree4' => ['fruits' => 17]
],
'data2' => [
     'tree5' => ['fruits' => 20],
     'tree6' => ['fruits' => 11],
     'tree7' => ['fruits' => 13],
     'tree8' => ['fruits' => 17]
]];

$max_fruit = max(array_map(function ($d) { return max(array_column($d, 'fruits')); }, $data));

$output = array();
foreach ($data as $set) {
    foreach ($set as $key => $value) {
        if ($value['fruits'] == $max_fruit) {
            $output[$key] = $max_fruit;
        }
    }
}
print_r($output);

在这种情况下，输出是：

Array
(
    [tree1] => 20
    [tree3] => 20
    [tree5] => 20
)

Demo on 3v4l.org