Question

如何转动此阵列：

$details = ["Dog" => "Natahlia", "Cat" => "Ryan", "Bird" => "Natahlia"];

进入此（所需输出）：

$details = [["Natahlia"=>["Dog","Bird"], "Ryan"=>"Cat"];

由于我的代码连接了值或者覆盖了它，所以遇到了一些麻烦。

$arr = array();
foreach($details as $key => $value){
   if(array_key_exists($value,$arr)){
      //this part i dont know what to do since += wont do it since it's a string and .= concatenates it
      $arr[$value] = $key;
   } else {
      $arr[$value] = $key;
   }
}
return $arr;

Answer 1

无需循环整个阵列您只需要循环唯一的名称并使用该名称执行array_intersect array_intersect将返回匹配的名称，并将键作为动物返回，所以array_keys可以得到你想要的结果。
这只会循环使用唯一的名称，因此它可能比循环整个数组更快。

$details = ["Dog" => "Natahlia", "Cat" => "Ryan", "Bird" => "Natahlia"];


foreach(array_unique($details) as $name){
    $new[$name] = array_keys(array_intersect($details, [$name]));
}
var_dump($new);

输出：

array(2) {
     ["Natahlia"] => array(2) {
            [0] => "Dog"
            [1] => "Bird"
    }
    ["Ryan"] => array(1) {
            [0] => "Cat"
    }
}

https://3v4l.org/paYRJ

Answer 2

<?php

$details = ["Dog" => "Natahlia", "Cat" => "Ryan", "Bird" => "Natahlia"];

foreach($details as $animal => $name)
    $result[$name][] = $animal;

var_export($result);

输出：

array (
'Natahlia' => 
array (
    0 => 'Dog',
    1 => 'Bird',
),
'Ryan' => 
array (
    0 => 'Cat',
),
)

如何在PHP中按值获取所有键的数组？

2 个答案: