php - 如何按特定值对数组进行分组？

Question

我有一个这样的数组:

$files = array(
    "Input.txt" => "Randy",
    "Code.py" => "Stan",
    "Output.txt" => "Randy"
);

我想按其所有者对文件进行分组并像这样返回:

[
    "Randy" => ["Input.txt", "Output.txt"], 
    "Stan" => ["Code.py"]
]

我试着这样做:

<?php 
class FileOwners 
{
   public static function groupByOwners($files)
   {
       foreach ($files as $file => $owner){
          $data[$owner] = $file;
       };
       return $data;
   }
}
$files = array(
    "Input.txt" => "Randy",
    "Code.py" => "Stan",
    "Output.txt" => "Randy"
);
var_dump(FileOwners::groupByOwners($files));

但我得到的是:

array(2) {
    ["Randy"]=>string(10) "Output.txt",
    ["Stan"]=>string(7) "Code.py"
}

请帮助如何制作它。

Answer 1

你正在覆盖 $data，使用 $data[$owner][] = $file; 而不是 $data[$owner]= $file;

public static function groupByOwners($files)
   {
       foreach ($files as $file => $owner){
          $data[$owner][] = $file;
       };
       return $data;
   }