动态地仅从数组中提取某些键

Question

我只需要动态地从数组中提取某些键。

Ex：

$array = [
        "a" => true,
        "b" => false,
        "c" => [
            0 => [
                "a" => "x",
                "b" => [
                    "x" => "Y"
                ]
            ],
            1 => [
                "a" => "x",
                "b" => [
                    "x" => "Y"
                ]
            ],
        ]
    ];

然后，我需要提取以下可以更改的数组：

$newArray = [
        "b" => false,
        "c" => [
            0 => [
                "b" => [
                    "x" => "Y"
                ]
            ],
            1 => [
                "b" => [
                    "x" => "Y"
                ]
            ],
        ]
    ];

Answer 1

使用以下递归函数可能很容易：

<?php
$array = [
            "a" => true,
            "b" => false,
            "c" => [
                0 => [
                    "a" => "x",
                    "b" => [
                        "x" => "Y"
                    ]
                ],
                1 => [
                    "a" => "x",
                    "b" => [
                        "x" => "Y"
                    ]
                ],
            ]
        ];

$cleaned_array = unset_by_key($array,"a");    
$extracted_array = arrayRecursiveDiff ($array, $cleaned_array);

print_r($cleaned_array);  
print_r($extracted_array);

function unset_by_key ($arr,$nkey) {
  unset($arr[$nkey]);
  foreach ($arr as $key=>$val) {
    if (is_array($val)) {
        $arr[$key] = unset_by_key($val,$nkey);
    }
  }
  return $arr;
}

// THX TO: https://stackoverflow.com/questions/3876435/recursive-array-diff
function arrayRecursiveDiff($aArray1, $aArray2) {
  $aReturn = array();

  foreach ($aArray1 as $mKey => $mValue) {
    if (array_key_exists($mKey, $aArray2)) {
      if (is_array($mValue)) {
        $aRecursiveDiff = arrayRecursiveDiff($mValue, $aArray2[$mKey]);
        if (count($aRecursiveDiff)) { $aReturn[$mKey] = $aRecursiveDiff; }
      } else {
        if ($mValue != $aArray2[$mKey]) {
          $aReturn[$mKey] = $mValue;
        }
      }
    } else {
      $aReturn[$mKey] = $mValue;
    }
  }
  return $aReturn;
} 

?>

Answer 2

不需要递归函数，如果您只想通过第一级键选择深度，则可以只使用array_intersect_key：

$arr = [
    'a' => true,
    'b' => false,
    'c' => [
        [
            'a' => 'x',
            'b' => [
                'x' => 'Y'
            ]
        ],
        [
            'a' => 'x',
            'b' => [
                'x' => 'Y'
            ]
        ],
    ]
];
function getKeys(array $arr, array $keys) {
    return array_intersect_key($arr, array_fill_keys($keys, null));
}

$result = getKeys($arr, ['b', 'c']);
print_r($result);

希望有所帮助，