Drupal Stock module

function test_process_data($data, $headers) {
  $columns = array();
  $i = 0;
  foreach ($headers as $key => $value) {
    $field = $data[$i++];     // <- This is where the problem was occuring

    // Special handling for some fields
    switch ($key) {
      case 'symbol':
        $columns[] = _add_full_quote($field);
        break;
      case 'name': 
        $columns[] = $field;
        break;
      case 'change_amt':
        $columns[] = _right_align(_up_down_tick(_decimals($field)));
        break;
      case 'current_price':
      case 'opening':
      case 'high':
      case 'low':
        $columns[] = _right_align(_decimals($field));
        break;
      case 'volume':
        $columns[] = _right_align($field);
        break;
      default:
        $columns[] = $field;
        break;
    }
  }

  return $columns;
}