- array_map: documentation ( source)
- var_dump: documentation ( source)
- array_filter: documentation ( source)
<?php
$a = array( 0 => array() );
var_dump( empty( $a ) );
var_dump( array_filter( $a ) );
var_dump( array_filter( array_map( 'array_filter', $a ) ) );
var_dump( !empty( $a[0] ) );