The current fieldsmapping should use the views rendered value and not the raw value.

According merlinofchaos we should refactor the graph generating code

//merlinofchaos> ClemensTolboom: $view->field[$field_id]->field_alias should then match 'comment_node_cid'.
//merlinofchaos> ClemensTolboom: Though in general you should try to avoid ever referencing what's in $row directly if you can.
//merlinofchaos> ClemensTolboom: There's always things like $view->style_plugin->rendered_fields[] and $view->field[$id]->get_value()