Yet Another Related Posts Plugin

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Today I’m releasing Yet Another Related Posts Plugin (YARPP1) 1.0 for WordPress. It’s the result of some tinkering with Peter Bowyer’s version of Alexander Malov & Mike Lu’s Related Entries plugin. Modifications made include:

  1. Limiting by a threshold: Peter Bowyer did the great work of making the algorithm use [[mysql]]’s fulltext search score to identify related posts. But it currently just displayed, for example, the top 5 most “relevant” entries, even if some of them weren’t at all similar. Now you can set a threshold limit2 for relevance, and you get more related posts if there are more related posts and less if there are less. Ha!
  2. Being a better plugin citizen: now it doesn’t require the user to click some sketchy button to alter the database and enable a fulltext key. Using register_activation_hook, it does it automagically on plugin activation. Just install and go!
  3. Miscellany: a nicer options screen, displaying the fulltext match score on output for admins, an option to allow related posts from the future, a couple bug fixes, etc.


Just put it in your /wp-content/plugins/ directory, activate, and then drop the related_posts function in your WP loop. Change any options in the Related Posts (YARPP) Options pane in Admin > Plugins.

You can override any options in an individual instance of related_posts using the following syntax:

related_posts(limit, threshold, before title, after title, show excerpt, len, before excerpt, after excerpt, show pass posts, past only, show score);

Most of these should be self-explanatory. They’re also in the same order as the options on the YARPP Options pane.

Example: related_posts(10, null, 'title: ') changes the maximum related posts number to 10, keeps the default threshold from the Options pane, and adds title: to the beginning of every title.

There’s also a related_posts_exist() function. It has three optional arguments to override the defaults: a threshold, the past only boolean, and the show password-protected posts boolean.


For a barebones setup, just drop <?php related_posts(); ?> right after <?php the_content() ?>.

On my own blog I use the following code with <li> and </li> as the before/after entry options:

<?php if (related_posts_exist()): ?>
Related posts:
  <?php related_posts(); ?>
<?php else: ?>
<p>No related posts.</p>
<?php endif; ?>

Coming soon (probably)

  • Incorporation of tags and categories in the algorithm. I’ve gotten the code working, but I still need to think about what the most natural algorithm would be for weighing these factors against the mysql fulltext score currently used (and works pretty well, I must say).
  • Um, something else! Let me know if you have any suggestions for improvement. ^^
  1. Pronounced “yarp!”, kind of like this, but maybe with a little more joy:

  2. Did you know that threshold has only two h’s!? I’m incensed and just went through and replaced all the instances of threshhold in my code. It’s really not a thresh-hold!?