How are a user's tags formulated?

Question

This is more a curiosity than a pressing question (even though I tagged it as "bug"). But I noticed that my account "tags" seem to change over time. I figured some algorithm looked at my questions and answers and somehow decided to tag what it thought my specialties to be, accordingly. Then, today, I noticed my tags as "greek", "fonts" and "siunitx".

Now I can understand "greek" as a tag, since an old answer of mine recently received some attention concerning upright greek symbols. Fonts? OK, I'll buy that one too, though it is a bit of a stretch. But "siunitx"???! I am embarassed to admit it, but I've never even voluntarily loaded the package (except if the OP's preamble does). Five hours ago, I left a comment on Getting ! instead of comparison sign < in cases that mentioned the word "siunitx". The comment got 3 upvotes.

Is that apparently enough to tag me as... what? Proficient in "siunitx"? If that is all it takes to tag a user, I had misplaced faith in the tagging algorithm.

Answer 1

First of all, the tags represented on the Users page is dependent on the current time filter. So, you might see a different set of tags under each user depending on whether you filter by week, month, quarter, year or overall.

Now, let's focus on the tags displayed under your user when filtering by week:

You've earned 120 reputation this week. Nice.

Your tags are greek, fonts and siunitx. These correspond to the highest-voted, active posts you are involved in this week. To obtain a list of posts that match some of these criteria, we can use the following ninja search: lastactive:7d.. [greek] and then sort by votes. Here are the top four results:

Knowing one of your tags is listed as greek, I've included that in the search query, since there's no other easy way to identify these posts. The top result possesses the tags fonts, siunitx and greek (sorted in order of popularity), matching those in your user flair (sorted in order of popularity associated with you). Since you're not that active under {siunitx}, it's listed last.