In April 2013 I posed the question: has anyone ever tried to perform social network analysis on Reddit by visualising the links between different subreddits? As you can see from the discussion on that page, several other attempts have also been made at answering this question, mainly by using sidebar links to define connections between subreddits.
This page is my first attempt at answering this question in a new way. I've produced two graphs showing links between subreddits:
In this interactive map, associations are defined when a redditor posts a link to one subreddit in another subreddit. The data was cropped quite heavily to make the map readable so some of your favourite subs (most notably the big ones) may be missing.
Like the self-posts map, only much bigger. In this interactive map, associations are defined by common links (known in Reddit vernacular as 'cross-posts', or more simply 'xposts'), i.e. if the same website is linked to from two different subreddits, then that's an association. There's much more data here, including the big subreddits. The subs are arranged so that they should be grouped with other subs of a similar subject. Clicking on a sub will show its local network - this is all the other subs that have contained similar content at some point. Beware, this dataset is quite big and may take a while to load!