如何在没有手动迭代的情况下交叉多维数组？

Question

I have two multidimensional arrays, example:

array(
  'a' => array(
    'code1' => array('v1', 'v2'),
    'code2' => array('v1', 'v2')
  ),
  'b' => array(
    'code3' => array('v1', 'v2'),
    'code4' => array('v1', 'v2'),
    'code5' => array('v1', 'v2'),
    'code6' => array('v1', 'v2')
  )
)

and

array(
  'a' => array(
    'code1' => '',
  ),
  'b' => array(
    'code5' => ''
  )
)

My desired result is:

array(
  'a' => array(
    'code1' => array('v1', 'v2')
  ),
  'b' => array(
    'code5' => array('v1', 'v2')
  )
)

I'm pretty sure it could be possible using one of built-in php functions, however I'm stuck with it, and can't find a solution rather than manually iterating through array. Can you help me with that?

Answer 1

The exact solution would depend on what you want to happen if the two arrays don't exactly match key-wise, but one way to reach your desired result is:

$a = array(
  'a' => array(
    'code1' => array('v1', 'v2'),
    'code2' => array('v1', 'v2')
  ),
  'b' => array(
    'code3' => array('v1', 'v2'),
    'code4' => array('v1', 'v2'),
    'code5' => array('v1', 'v2'),
    'code6' => array('v1', 'v2')
  )
);

$b = array(
  'a' => array(
    'code1' => '',
  ),
  'b' => array(
    'code5' => ''
  )
);

$result = array();
foreach ($a as $key => $data) {
    $result[$key] = array_intersect_key($data, $b[$key]);
}

The idea is to use array_intersect_key to keep only those elements from $a that appear (as keys) in $b.