How to hide Fivestar field when editing a comment from another user?
The code in the edit doesn't work, because $form_state['values'] isn't present before the submit. This is the correct code:

function hiderating_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  global $user;
  if ($form_id == "comment_node_article_form") {
   if ($form['uid']['#value'] != $user-&gt;uid AND $form['uid']['#value'] != 0) { 
    unset($form['field_stars']);
   }
  }
}


Using dpm($form), I discovered that $form['uid']['#value'] returns the uid from the user who wrote the comment. The value is only different from 0 if a comment is edited. When a user writes a new comment, the uid from the form is 0. That's why the AND in the second if is necessary.