(Previous Post: Part 4)

Tags

When someone submits a story to Steemit, they get to create up to five tags for the article (the first tag is the story's main category). On Steemit.com, tags (or topics) work like forums or Subreddits, if you are familiar with that other social media platform. Steemit will allow you to browse the list of recent posts within a topic, hot posts, trending posts, and promoted posts.

However, tags are not moderated, so consistency becomes a problem. I have discovered that there are many tags which probably would have been consolidated if this was a moderated platform. For example, there is a #steem-dev and a #steemdev tag, the difference being a single hyphen in the topic name. If someone wanted to post to both of those, they would need to use up two of their five possible tags.

Note: This is a problem that chainBB attempts to solve.

Retrieve Tags

Similar to the getFollowers() API in Part 2, there is an API function that allows you to chunk through all of the tags 1000 at a time in order of popularity. getTrendingTags() takes a starting tag name and the number of results to return (max 1000). If the starting tag name is empty, then it will begin at the top.

We can create a function to fetch all of the tags (~20,000 or so when this was written) into a single array by using a generator function that yields on each call to getTrendingTags():

  //Tags most popular first. First argument is for chunk start
  let getTagsList = P.coroutine(function* () {
    let start = ''
    let count = 0
    let allTags = []

    do {
      yield steem.api.getTrendingTagsAsync(start, 1000)
        .then(function (result) {
          if (result == null || result.length == 0) {
            count = 0
          } else {
            count = result.length
            start = result[count - 1].name
            Array.prototype.push.apply(allTags, result)
          }
        })
        .catch(function(err) {
          // There seems to be an error in the data or node code that causes requests
          // at the bottom of the list to fail (i.e., data after tag "yunks"). For the
          // sake of this demo, we will just exit
          count = 0;
        })
    } while (count === 1000);

    return allTags
  })

  getTagsList().then(console.log)

Each item in the returned array will contain data resembling:

{
  comments: 48673,
  name: "steemit",
  net_votes: 478456,
  top_posts: 29484,
  total_payouts: "3946608.019 SBD",
  trending: "243461804"
}

What Can We Do With This?

If you just want to create a tag cloud, then retrieving all 20,000 tags would be pretty wasteful - the important tags for a tag cloud would definitely be in the top 1000 or less. But, having the entire list of tags could be used to offer suggestions for similar tags that are more popular.

For instance, suppose that someone creates a post with your web app and wants to tag it with "steem-dev". While this is a category with great content, the "steemdev" one is even more popular, so your app may want to suggest that as an alternative and let the author decide.

Using string-based filtering logic to trim non-alphanumeric characters, or normalize accented characters, may resemble this:

function findSimilarTags (allTags, tag) {
  const input = tag.toLowerCase()
  const filtered = _.filter(allTags, function(t) {
    return t.name === input || t.name === _.deburr(input) || t.name === input.replace(/\W/g, '')
  })
  console.log(filtered)
}

findSimilarTags(allTags, "steem-dev")

Results:

[{
  comments: 225,
  name: "steemdev",
  net_votes: 4971,
  top_posts: 82,
  total_payouts: "72089.717 SBD",
  trending: "959477"
}, 
{
  comments: 64,
  name: "steem-dev",
  net_votes: 365,
  top_posts: 18,
  total_payouts: "18893.227 SBD",
  trending: "256195"
}]

(Next Post: Part 6)