gistfile1.js

            <ul class="actor-links">

{% assign post_actor_ids =  site.posts | map: 'actor_ids' | join: ','  | split: ',' | sort %}
{% assign actor_and_count = '' | split: '.' %}

{% for actor in site.actors %}
  {% assign count = 0 %}
  {% for post_actor_id in post_actor_ids %}
    {% if actor.actor_id == post_actor_id %}
      {% assign count = count | plus: 1 %}
    {% endif %}
  {% endfor %}
  {% include mkhash.inc actor = actor count = count %}
  {% assign actor_and_count = actor_and_count | push: h %}
{% endfor %}

{% assign sorted_actor_and_count = actor_and_count | sort: 'count' %}

              {% for item in sorted_actor_and_count reversed %}
                {% assign actor = item.actor %}
              <li class="actor-links__item">
                <a href="{{ actor.url }}">
                  <img src="{{ actor.image_url | prepend:site.baseurl }}" alt="{{ actor.title }}" class="actor-image" width="80" height="80">
                  <br>
                  {{ actor.title }}
                  ({{ item.count }})
                </a>
              </li>
              {% endfor %}
            </ul>