[WordPress]カテゴリーを単一チェックのラジオボタンに変更

functions.php

function my_print_footer_scripts() {
echo '<script type="text/javascript">
  //<![CDATA[
  jQuery(document).ready(function($){
    $(".categorychecklist input[type=checkbox]").each(function(){
      $check = $(this);
      var checked = $check.attr("checked") ? \' checked="checked"\' : \'\';
      $(\'<input type="radio" id="\' + $check.attr("id")
        + \'" name="\' + $check.attr("name") + \'"\'
    + checked
  + \' value="\' + $check.val()
  + \'"/>\'
      ).insertBefore($check);
      $check.remove();
    });
  });
  //]]>
  </script>';
}
add_action('admin_print_footer_scripts', 'my_print_footer_scripts', 21);