regex php for comma

gistfile1.php

// loop through posts, populating $departments arrays
  foreach($posts as $post) {
    $deps = strip_tags( get_post_meta( $post->ID, '_cmb_department_text', TRUE ));
    preg_match_all("/,\s*/", $deps, $matches ); 
    $result = array_combine($matches[1], $matches[2]);
    $departments[$result][] = $post;
  }