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:

Array ( [0] => Array ( [Name] => [EmailAddress] => ) ) 

(And so on, if there's more data, although there may not be...)

If it looks like the above, I want it to be completely empty after I've processed it.

So print_r($array); would output:

Array ( )

If I run $arrayX = array_filter($arrayX); I still get the same print_r output. Everywhere I've looked suggests this is the simplest way of removing empty array elements in PHP5, however.

I also tried $arrayX = array_filter($arrayX,'empty_array'); but I got the following error:

Warning: array_filter() [function.array-filter]: The second argument, 'empty_array', should be a valid callback

What am I doing wrong?

Answer 1

Try using array_map() to apply the filter to every array in $array:

$array = array_map('array_filter', $array);
$array = array_filter($array);

Demo: http://codepad.org/xfXEeApj

Answer 2

There are numerous examples of how to do this. You can try the docs, for one (see the first comment).

function array_filter_recursive($array, $callback = null) {
    foreach ($array as $key => & $value) {
        if (is_array($value)) {
            $value = array_filter_recursive($value, $callback);
        }
        else {
            if ( ! is_null($callback)) {
                if ( ! $callback($value)) {
                    unset($array[$key]);
                }
            }
            else {
                if ( ! (bool) $value) {
                    unset($array[$key]);
                }
            }
        }
    }
    unset($value);

    return $array;
}

Granted this example doesn't actually use array_filter but you get the point.

Answer 3

The accepted answer does not do exactly what the OP asked. If you want to recursively remove ALL values that evaluate to false including empty arrays then use the following function:

function array_trim($input) {
    return is_array($input) ? array_filter($input, 
        function (& $value) { return $value = array_trim($value); }
    ) : $input;
}

Or you could change the return condition according to your needs, for example:

{ return !is_array($value) or $value = array_trim($value); }

If you only want to remove empty arrays. Or you can change the condition to only test for "" or false or null, etc...

Answer 4

Following up jeremyharris' suggestion, this is how I needed to change it to make it work:

function array_filter_recursive($array) {
   foreach ($array as $key => &$value) {
      if (empty($value)) {
         unset($array[$key]);
      }
      else {
         if (is_array($value)) {
            $value = array_filter_recursive($value);
            if (empty($value)) {
               unset($array[$key]);
            }
         }
      }
   }

   return $array;
}