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Ask HN: Algorithm arranging posts on HN?
I have noticed something on hn, that the posts on the main page gets arranged in a peculiar way. For example, a link posted 4 hours ago with less than 20 upvotes might be on the main page still, while another similarly aged link with twice as much upvotes might be on the second page.<p>I am wondering what algorithm is used in ordering them. Any idea?
- kingsidharth 16y agoOne word: Yes. (Duh!) FAQ: http://ycombinator.com/newsfaq.html http://ycombinator.com/newsfaq.html
- bhavin 16y agoumm, the faq on this doesn't really explain the scenario... the question was something like this... how come a 20 upvote link gets displayed higher than a 40 upvote link when both are carrying similar timestamps?
- kingsidharth 16y agoYes. Vote/Time Elapsed
- gasull 16y agoYou're stating the obvious without really replying to bhavin.
- RiderOfGiraffes 16y agoThere are several small tweaks that I've noticed. There's something about the length of a post, possibly something about the number of comments, and possibly others. There are also penalties for various things. Items without a link are ranked more lowly than those with a link, and some topics du jour have a penalty applied. All in all, it's actively curated by PG, with small changes to keep the system in balance and running smoothly. Enquiring too closely is discouraged. It's also plausible that this item will get deleted. After all, this is a site for hackers, not a site about Hacker News.
- bhavin 16y agoAgreed! I understand that there's always more chance that if its fully disclosed, it might be used to game the system.. but could stop my curiousity, hence the question :).
- gasull 16y agoI noticed that this morning too: http://news.ycombinator.com/item?id=1966201 http://news.ycombinator.com/item?id=1966201
- pelf 16y agohttp://news.ycombinator.com/item?id=1781013 http://news.ycombinator.com/item?id=1781013 quoting from PG's comment on that post: (= gravity* 1.8 timebase* 120 front-threshold* 1 nourl-factor* .4 lightweight-factor* .17 gag-factor* .1) (def frontpage-rank (s (o scorefn realscore) (o gravity gravity*)) (* (/ (let base (- (scorefn s) 1) (if (> base 0) (expt base .8) base)) (expt (/ (+ (item-age s) timebase*) 60) gravity)) (if (no (in s!type 'story 'poll)) .8 (blank s!url) nourl-factor* (mem 'bury s!keys) .001 (* (contro-factor s) (if (mem 'gag s!keys) gag-factor* (lightweight s) lightweight-factor* 1))))) ----- or simplifying a bit: Score = (P-1) / (T+2)^G where, P = points of an item (and -1 is to negate submitters vote) T = time since submission (in hours) G = Gravity, defaults to 1.8 in news.arc