Over at FiveThiryEight, Trevor Martin has used semantic analysis to break down subreddits and find similarities between communities.
So what does that mean? It means you can add and subtract subreddits to show a commonality among the users. So for example, if you add r/minnesota and r/nba together you get r/timberwolves (their local basketball team). The article spends most of its time looking at r/the_donald. It turns out that if you subtract r/politics from he mix you get a bunch of hate subreddits.
You can do your own math here.