calculate rating based on sum of other ratings

Fivestar has no built-in support for what you're describing. Anything like this you'll need to manually query the results from VotingAPI and calculate results yourself.

Once multi axis rating gets implemented, I'm sure a lot of people would like an easy way of setting up a view with the votes from all the criteria and a calculated average. I haven't done views integration, so I don't know how hard such a feature would be to implement.

I also think vote-averaging is a very obvious feature to want for multi-axis. I'm doing it like this right now:

/**
 * Implementation of hook_votingapi_results_alter()
 *
 * Finds content with vote tags other than 'vote'
 * and replaces the vote average with an average
 * of the other tags. For multi-axis voting.
 */
function MYMODULE_votingapi_results_alter(&$cache, $content_type, $content_id) {
  $vote_avg_sum = 0;
  $vote_avg_count = 0;
  $vote_tags = 0;
  
  foreach($cache as $tag => $data) {
    if($tag != 'vote') {
      $vote_avg_sum += $data['percent']['average'];
      $vote_avg_count += $data['percent']['count'];
      $vote_tags++;
    }
  }
  if($vote_tags > 0) {
    $cache['vote']['percent']['average'] = $vote_avg_sum/$vote_tags;
    $cache['vote']['percent']['count'] = $vote_avg_count/$vote_tags;
  }
}

Fivestar for Drupal 6

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