PHP associative array with keys initialized with array-CodePudding

so I am trying to have an associative key that has the value of an array. And whenever I find a new value that is not a key in the Map then it should initialize the key with a value of an empty array otherwise if the key is already there then add to that value array

Here is the code, there is comments as well for easy reading.

Thank you!

  <?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);

Here is the input array

<?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"])
);

CodePudding user response：

One way to produce the output would be to grab all categories, flatten it into a single array then remove dupes, loop over it and then use in_array to match the itemName for the key if the category exists in categories.

<?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);

Result: (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
        )

)