>I used my own metric that is based on jaccard similarity. Which in turn is based on "users who posted to X also posted to Y" metric.

Is that really a good metric of similarity? Just myself, I post in several unrelated subreddits semi-regularly from programming to video games to music, art and even stone masonary, i've posted in subreddits for TV shows i've watched, or just completely random things.

I use reddit as a place where I can learn about and interact with people on nearly any subject or topic and I take advantage of that when I can. I'm sure my posting habits aren't that unusual. I'm just not sure that's really an accurate way to gauge similarity.