PHP 具有用数组初始化的键的关联数组

Question

所以我想要一个具有数组值的关联键。每当我在 Map 中找到一个不是键的新值时，它应该用空数组的值初始化键，否则如果键已经存在，则添加到该值数组

这里是代码，还有注释，方便阅读。

谢谢！

  <?php
    include_once("./array.php");
    ?>
    <?php
    
$categories = [];
$categoryMap=array();
#map to find with the category as the key then the item as the value 
foreach ($items as $key => $value) {
    # code...
    $currentCategories = $value['categories'];
    for ($i = 0; $i < sizeof($currentCategories); $i++) {
        # code...

        

        // if not in keys for the categoryMap then initialize with the key with a value of an empty array
        // otherwise just add the the array of values using that keys
        
        // visual of how it should be 
        // [
        //     'buger':['bun','tomato','sauce']

        // ]
        
        array_push($categories, $currentCategories[$i]);
    }
}
$categories = array_unique($categories);

这是输入数组

<?php



$items = array(
    array("itemName" => "Hat", "price" => 10.99, "categories" => ["apparel", "head"]),
    array("itemName" => "Scarf", "price" => 7.99, "categories" => ["apparel", "neck"]),
    array("itemName" => "Watch", "price" => 19.99, "categories" => ["jewelry", "electronics"]),
    array("itemName" => "Necklace", "price" => 99.99, "categories" => ["jewelry", "neck"]),
    array("itemName" => "Headphones", "price" => 29.99, "categories" => ["head", "electronics"])
);

Answer 1

生成输出的一种方法是抓取所有类别，将其展平为单个数组，然后删除重复项，循环遍历它，然后使用 in_array 匹配键的 itemName（如果类别存在）在类别中。

<?php
$items = array(
    array("itemName" => "Hat", "price" => 10.99, "categories" => ["apparel", "head"]),
    array("itemName" => "Scarf", "price" => 7.99, "categories" => ["apparel", "neck"]),
    array("itemName" => "Watch", "price" => 19.99, "categories" => ["jewelry", "electronics"]),
    array("itemName" => "Necklace", "price" => 99.99, "categories" => ["jewelry", "neck"]),
    array("itemName" => "Headphones", "price" => 29.99, "categories" => ["head", "electronics"])
);


foreach (array_unique(array_merge(...array_values(array_column($items, 'categories')))) as $value) {
   foreach ($items as $item) {
      if (in_array($value, $item['categories'])) {
          $categories[$value][] = $item['itemName'];
      } 
   }
}

print_r($categories);

结果： (Online example)

Array
(
    [apparel] => Array
        (
            [0] => Hat
            [1] => Scarf
        )

    [head] => Array
        (
            [0] => Hat
            [1] => Headphones
        )

    [neck] => Array
        (
            [0] => Scarf
            [1] => Necklace
        )

    [jewelry] => Array
        (
            [0] => Watch
            [1] => Necklace
        )

    [electronics] => Array
        (
            [0] => Watch
            [1] => Headphones
        )

)

PHP 具有用数组初始化的键的关联数组

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