title: Filter wp_list_categories from one custom post type
body: <p>I have 2 custom post types called 'project' and 'client' that share a taxonomy called 'sector'.</p>
  
  <pre><code>if (!is_taxonomy('sector')) {
          register_taxonomy(
          'sector', array('project', 'client'), array(
          'hierarchical' =&gt; true,
          'label' =&gt; 'Sector',
          'query_var' =&gt; true,
          'rewrite' =&gt; array( 'slug' =&gt; 'sector' ),
          'with_front' =&gt; false
          ) );
  
          wp_insert_term('Health', 'sector');
          wp_insert_term('Clubs', 'sector');
          wp_insert_term('Commercial', 'sector');     
      }
  </code></pre>
  
  <p>I have created a taxonomy archive template with a sidebar nav that lists links to my taxonomy archives using:</p>
  
  <pre><code>//list terms in a given taxonomy using wp_list_categories 
  
      $orderby      = 'name'; 
      $show_count   = 1;      // 1 for yes, 0 for no
      $pad_counts   = 0;      // 1 for yes, 0 for no
      $hierarchical = 0;      // 1 for yes, 0 for no
      $show_option_none='';
      $title        = '';
  
      $args_sector = array(
        'taxonomy'     =&gt; 'sector',
        'orderby'      =&gt; $orderby,
        'show_count'   =&gt; $show_count,
        'pad_counts'   =&gt; $pad_counts,
        'hierarchical' =&gt; $hierarchical, 
        'title_li'     =&gt; $title
      );
  
  
  &lt;ul id="sideNav" class="rightSubMenu"&gt;   
        &lt;h3 class="rightSubNav"&gt;SECTOR&lt;/h3&gt;
        &lt;ul id="sideNav" class="rightSubMenu"&gt;
          &lt;?php wp_list_categories( $args_sector ); ?&gt;
        &lt;/ul&gt;
  
  &lt;/ul&gt;
  </code></pre>
  
  <p>The problem is if I have a project that is linked to 'clubs' and a client that is linked to 'clubs' the output count shows 2. Also the archive page shows 2 posts - 1 for project and one for client. But there is only one project.</p>
  
  <p>I am mainly concerned with the project page and would like to filter the results by my 'project' post type. I looked through the codex and the wp_list_categories function doesn't seem to accept a parameter to do this.</p>
  
  <p>Can anyone help? Is there a better way to do this?</p>