Question

我正在尝试遍历JSON多维数组，并为每个商店获取最低的distance值，并将其与location_id值一起打印。

除了这里我所没有的，我无所不能。我已经尝试通过搜索stackoverflow来尝试一百万个选项，但无法弄清楚我在做什么错。

我的JSON数据如下：

$json = '{
  "shops": [
   {
      "shop_id": "100",
          "locations": [
                { "location_id": "100_1", "distance": "10.3" },
                { "location_id": "100_2", "distance": "15.2" }
          ]
    },
    {
      "shop_id": "101",
          "locations": [
                { "location_id": "101_1", "distance": "19.3" },
                { "location_id": "101_2", "distance": "12.4" }
          ]
    }]
}';

现在，我的代码是：

// Decode the JSON data
$json_data = json_decode($json,true);

// Do a foreach loop
foreach($json_data['shops'] as $shops){

echo $shops['shop_id'].', ';

// Currently prints:
// 101, 102 ,

// But I need it to print:
// 100_1 -> 10.3, 101_2 -> 12.4

}

我尝试将另一个foreach循环放入现有循环中，但是只打印出1。

我该如何实现？我不能把头缠住它。我需要为每个distance

打印最低的['shop_id']['locations']值

Answer 1

您可以使用array_column提取特定商店的所有距离，然后在该数组上使用min以获取最低值。为了获得位置，我们然后使用array_search来找到具有该值的最小键，并使用它来为商店获取合适的location_id：

foreach($json_data['shops'] as $shops) {
    $distances = array_column($shops['locations'], 'distance');
    $locations = array_column($shops['locations'], 'location_id');
    $min = min($distances);
    $location = array_search($min, $distances);
    echo $locations[$location] . ' -> ' . $min . "\n";
}

输出：

100_1 -> 10.3 
101_2 -> 12.4

Demo on 3v4l.org

更新

正如@Andreas在评论中指出的那样，我们可以使用array_column的第三个参数以其location_id为键来获取距离数组。然后，我们可以对数组进行排序，并使用current和key获得最小距离和相应的位置：

foreach($json_data['shops'] as $shops) {
    $distances = array_column($shops['locations'], 'distance', 'location_id');
    asort($distances);
    echo key($distances) . ' -> ' . current($distances) . "\n";
}

输出：

100_1 -> 10.3 
101_2 -> 12.4

Demo on 3v4l.org

Answer 2

您可以使用子循环来尝试选择最小距离。易于遵循代码并构造结果数组：

<?php
$json = '{
  "shops": [
   {
        "shop_id": "100",
        "locations": [
            { "location_id": "100_1", "distance": "10.3" },
            { "location_id": "100_2", "distance": "15.2" }
        ]
    },
    {
        "shop_id": "101",
        "locations": [
            { "location_id": "101_1", "distance": "19.3" },
            { "location_id": "101_2", "distance": "12.4" }
        ]
    }]
}';

$data = json_decode($json, true);

$min_distances = [];
foreach($data['shops'] as $shop)
{
    $distance = null;
    foreach($shop['locations'] as $location)
    {
        if(is_null($distance) || $location['distance'] < $distance)
        {
            $distance = $location['distance'];
            $location_id  = $location['location_id'];
        }
    }
    $min_distances[] = [
        'shop_id'=>$shop['shop_id'], 
        'distance'=>$distance, 
        'location_id'=>$location_id
    ];
}
var_dump($min_distances);

输出：

 array(2) {
[0]=>
array(3) {
    ["shop_id"]=>
    string(3) "100"
    ["distance"]=>
    string(4) "10.3"
    ["location_id"]=>
    string(5) "100_1"
}
[1]=>
array(3) {
    ["shop_id"]=>
    string(3) "101"
    ["distance"]=>
    string(4) "12.4"
    ["location_id"]=>
    string(5) "101_2"
}
}

如何使用PHP从JSON数组中获取最低值

2 个答案: