Examine frequency of characters in Drupal code

mymodule.drush.php

<?php

/**
 * Implements hook_drush_command().
 */
function mymodule_drush_command() {
  $items['text-analysis'] = array(
    'description' => 'Analyse text.',
    'aliases' => array('ta'),
  );
  return $items;
}

/**
 * Command callback.
 */
function drush_mymodule_text_analysis() {
  $files = file_scan_directory('/path/to/drupal', '/.*module$|.*test$|.*install$|.*inc$/');
  $chars = array();
  foreach ($files as $file) {
    $data = file_get_contents($file->uri);
    $counts = count_chars($data, 1);
    foreach ($counts as $i => $c) {
      switch ($i) {
        case 10:
          $char = 'LF';
          break;
        case 32:
          $char = 'SPACE';
          break;
        default:
          $char = chr($i);
      }
      $chars[$char] = $chars[$char] + $c;
    }
  }
  arsort($chars);

  foreach ($chars as $char => $num) {
    if ($num > 400 && !in_array($char, range('a', 'z')) && !in_array($char, range('A', 'Z'))) {
      drush_print($char . " --- " . $num);
    }
  }
}