Foursquare this afternoon revealed a little more of the magic that makes the new Explore function so accurate and popular. Engineer Justin Moore published a post on the foursquare Engineering Blog that describes some of the work that went into creating the feature.
Explore â€” in development for more than eight months â€” went by the code-name “Rex,” which foursquare hinted at with the dinosaur artwork featured on their SXSW teaser page. Rex started by showing the most popular venues around, but quickly evolved to the more personalized recommendations we see today. Using some very advanced computational acrobatics, it takes into account things like the places your friends have been, the places similar users have been, similar places you’ve been in the past and so on.
To get a feel for how Explore would work outside the confines of foursquare headquarters, the team built a mobile web app that foursquare staff could use for testing. If it came up with their favorite hidden gems, they knew they were headed in the right direction. The mobile web app allowed developers to make changes on the fly rather than having them built into an app that needed to be updated each time a change was made.
Moore also addresses one of the hardest parts of building Explore â€” what to do with users who have no history or friends and are making a “cold start.” Foursquare, of course, doesn’t give away their secret sauce, but they do reveal some interesting trends they found for venues.
Venues tend to group themselves based on the average number of times they’ve been visited by particular users. Offices, for instance, have few users who’ve checked in, but each one has checked in many times. Restaurants can be grouped into the must-see places that users only visit a few times versus the places where visitors tend to become regulars. Foursquare analyzes those difference to make their recommendations.