Recursively remove empty elements and subarrays from a multi-dimensional array

Question

I can\'t seem to find a simple, straight-forward solution to the age-old problem of removing empty elements from arrays in PHP.

My input array may look like this: <

Answer 1

array_filter() is not type-sensitive by default. This means that any zero-ish, false-y, null, empty values will be removed. My links to follow will demonstrate this point.

The OP's sample input array is 2-dimensional. If the data structure is static then recursion is not necessary. For anyone who would like to filter the zero-length values from a multi-dimensional array, I'll provide a static 2-dim method and a recursive method.

Static 2-dim Array: This code performs a "zero-safe" filter on the 2nd level elements and then removes empty subarrays: (See this demo to see this method work with different (trickier) array data)

$array=[
    ['Name'=>'','EmailAddress'=>'']
];   

var_export(
    array_filter(  // remove the 2nd level in the event that all subarray elements are removed
        array_map(  // access/iterate 2nd level values
            function($v){
                return array_filter($v,'strlen');  // filter out subarray elements with zero-length values
            },$array  // the input array
        )
    )
);

Here is the same code as a one-liner:

var_export(array_filter(array_map(function($v){return array_filter($v,'strlen');},$array)));

Output (as originally specified by the OP):

array (
)

*if you don't want to remove the empty subarrays, simply remove the outer array_filter() call.

---

Recursive method for multi-dimensional arrays of unknown depth: When the number of levels in an array are unknown, recursion is a logical technique. The following code will process each subarray, removing zero-length values and any empty subarrays as it goes. Here is a demo of this code with a few sample inputs.

$array=[
    ['Name'=>'','Array'=>['Keep'=>'Keep','Drop'=>['Drop2'=>'']],'EmailAddress'=>'','Pets'=>0,'Children'=>null],
    ['Name'=>'','EmailAddress'=>'','FavoriteNumber'=>'0']
];

function removeEmptyValuesAndSubarrays($array){
   foreach($array as $k=>&$v){
        if(is_array($v)){
            $v=removeEmptyValuesAndSubarrays($v);  // filter subarray and update array
            if(!sizeof($v)){ // check array count
                unset($array[$k]);
            }
        }elseif(!strlen($v)){  // this will handle (int) type values correctly
            unset($array[$k]);
        }
   }
   return $array;
}

var_export(removeEmptyValuesAndSubarrays($array));

Output:

array (
  0 => 
  array (
    'Array' => 
    array (
      'Keep' => 'Keep',
    ),
    'Pets' => 0,
  ),
  1 => 
  array (
    'FavoriteNumber' => '0',
  ),
)

If anyone discovers an input array that breaks my recursive method, please post it (in its simplest form) as a comment and I'll update my answer.