Does a network graph of large subreddits already exist?

I'd be interested in a network graph like this that shows the connectedness between subreddits.

If it doesn't exist, would it be possible to form an alliance and make one?

We'd have to go through users, scrape the subreddits they post to, and treat those as "connected". I'd be curious to see which two hobbies unexpectedly appear together often.