tag trending分析 cn和kr相差到底有多少？

@nationalpark昨天给出了贴子Trending和Hot的区别,今天有时间来看下Tag的trending排序机制，和贴子的算法类似，也是用的reddit算法摘录,。tag plugin源代码可在这里查看，和trending想关的核心算法在这里，重点用**作了标注：

void add_stats( const tag_object& tag, const tag_stats_object& stats )const
{
_db.modify( stats, [&]( tag_stats_object& s )
{
if( tag.parent == comment_id_type() )
{
s.top_posts;
}
else
{
s.comments;
}
** s.total_trending += static_cast<uint32_t>(tag.trending); **
** s.net_votes += tag.net_votes; **
});
}

void update_tag( const tag_object& current, const comment_object& comment, double hot, double trending )const
{
const auto& stats = get_stats( current.tag );
remove_stats( current, stats );

   if( comment.cashout_time != fc::time_point_sec::maximum() ) {
     ** _db.modify( current, [&]( tag_object& obj ) ** {
         obj.active            = comment.active;
         obj.cashout           = _db.calculate_discussion_payout_time( comment );
         obj.children          = comment.children;
        ** obj.net_rshares       = comment.net_rshares.value; **
         ** obj.net_votes         = comment.net_votes; **
         obj.hot               = hot;
        ** obj.trending          = trending; **
         if( obj.cashout == fc::time_point_sec() )
           obj.promoted_balance = 0;
     });
     add_stats( current, stats );
   } else {
      _db.remove( current );
   }

}

/** finds tags that have been added or removed or updated */
void update_tags( const comment_object& c, bool parse_tags = false )const
{
try {

  ** auto hot = calculate_hot( c.net_rshares, c.created ); **
  ** auto trending = calculate_trending( c.net_rshares, c.created ); **

  const auto& comment_idx = _db.get_index< tag_index >().indices().get< by_comment >();

  if( parse_tags )
  {
     auto meta = filter_tags( c );
     auto citr = comment_idx.lower_bound( c.id );

     map< string, const tag_object* > existing_tags;
     vector< const tag_object* > remove_queue;

     while( citr != comment_idx.end() && citr->comment == c.id )
     {
        const tag_object* tag = &*citr;
        ++citr;

        if( meta.tags.find( tag->tag ) == meta.tags.end()  )
        {
           remove_queue.push_back(tag);
        }
        else
        {
           existing_tags[tag->tag] = tag;
        }
     }

    ** for( const auto& tag : meta.tags ) **
     {
        auto existing = existing_tags.find(tag);

        if( existing == existing_tags.end() )
        {
           create_tag( tag, c, hot, trending );
        }
        else
        {
          **  update_tag( *existing->second, c, hot, trending ); **
        }
     }

     for( const auto& item : remove_queue )
        remove_tag(*item);
  }
  else
  {
     auto citr = comment_idx.lower_bound( c.id );

     while( citr != comment_idx.end() && citr->comment == c.id )
     {
        update_tag( *citr, c, hot, trending );
        ++citr;
     }
  }

  if( c.parent_author.size() )
  {
     update_tags( _db.get_comment( c.parent_author, c.parent_permlink ) );
  }
  } FC_CAPTURE_LOG_AND_RETHROW( (c) )

}

    ** share_type        net_rshares; // reward is proportional to rshares^2, this is the sum of all votes (positive and negative)**
     share_type        abs_rshares; /// this is used to track the total abs(weight) of votes for the purpose of calculating cashout_time
     share_type        vote_rshares; /// Total positive rshares from all votes. Used to calculate delta weights. Needed to handle vote changing and removal.

总结：

1. tag trending对每一个comment的net_rshares采用类似reddit的trending算法后作累加，cn和kr差距到底是多少呢? 有兴趣的同学可以借助Steemdata这些来算不算
2. net_rshares 统计的是所有的奖励份额，upvote和flag都算，所以看到不合适CN区的评论和贴子大家放心踩，能提高cn tag排名。留言个沙发什么的提升不了CN排名，用steempower来投票，话说KR区有多少鲸鱼呢？ 谁知道？
3. comment包括主贴和评论，权重是一样的，为了CN区，大家要给好评论点赞
4. 目前贴子的所有tag都会累加当前贴子的trending值,只要tag里填上cn就是为CN区的排名作贡献

最后上个图看看，KR比CN整整多分发了一倍的SBD哦