How to filter out Categories for specific post types on Wordpress Admin?

Question

How can i programatically change the Category selection menu on wp-admin? is there a hook or filter to edit the Category List?

My objective is to filter out specific categories for specific post-types, for example:

I have the categories: Sports,Players and Coaches

under the post-types: People and Activities

I want to filter the Sports Category out of the People Post-type.

Answer 1

I went down the rabbit hole with this a few weeks ago. Never quite got it working right.

These might lead you in the right direction:

http://shibashake.com/wordpress-theme/add-custom-post-type-columns

http://wordpress.org/support/topic/category-column-for-custom-post-types?replies=3

Answer 2

i found the get_terms filter, that seemed to work fine for me:

  function filterCats($listCats){
    global $typenow;    
    if($typenow=='People'){
        foreach ($listCats as $k => $oCat) {
            if( $oCat->term_id == 6){//Sports Category id
                unset($listCats[$k]);
            }
        }
     }
     return $listCats;
 }
 add_filter('get_terms','filterCats');