This example shows how to show only Research and Scolarship IdPs.

Navigate to filter generator, https://discovery.eduteams.org/filter.php.

Click open the 'select entity categories' - accordion. You should now see all the possible entity categories to choose from in a grey box.

Move http://refeds.org/category/research-and-scholarship to green box. Move also http://id.incommon.org/category/research-and-scholarship.

At the bottom of the page you should see the resulting filter and it's plaintext version.