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> The reddit ranking algorithm is time-sensitive Can someone explain to me why on earth they would do this? It just seems like they're throwing variables in a

> The reddit ranking algorithm is time-sensitive Can someone explain to me why on earth they would do this? It just seems like they're throwing variables in a pot and coming up with ways to use them at that point.

Rifu 11y ago
I believe in this context it means that newer posts are ranked higher than older posts, which is pretty helpful in making sure the front page remains "fresh". [0] http://amix.dk/blog/post/19588 http://amix.dk/blog/post/19588 [1] http://www.outofscope.com/reddits-empire-no-longer-founded-on-a-flawed-algorithm/ http://www.outofscope.com/reddits-empire-no-longer-founded-o...
IanCal 11y ago
As I understand it, it is time-sensitive but indirectly. The number of votes compared to the age is important, but this isn't normalised compared to the current vote rate. There's a significant fluctuation in the number of people on reddit at different times of the day, so when you submit can be important.
- jkyle 11y ago
  This is absolutely correct. The algorithm is meant to quickly drop posts from the top. Such that even if a post has a record vote score, it still will only remain at the top for a few days. The amix link above didn't load for me today, but I like this scienceblogs post on the algorithm.[1] edit It should also be noted that since reddit is open source, you can always dig right in! [2] [1] http://scienceblogs.com/builtonfacts/2013/01/16/the-mathematics-of-reddit-rankings-or-how-upvotes-are-time-travel/ http://scienceblogs.com/builtonfacts/2013/01/16/the-mathemat... [2] https://github.com/reddit/reddit/blob/master/r2/r2/lib/db/_sorts.pyx https://github.com/reddit/reddit/blob/master/r2/r2/lib/db/_s...
  - ElvisMa 11y ago
    not only that, the ranking is also defined by the overall activity in the sub-reddit it is posted in. So you can see a post with fewer upvotes, posted later over a post which has a lot more upvotes posted earlier. Which means, even submissions to very small sub-reddits have a decent chance to be promoted to trending and to r/all even
    - deleted 11y ago
      [deleted]
    - jkyle 11y ago
      The trending or 'hot' algorithm is a bit different than the "top" algorithm. I believe you're referring to the 'hot' algorithm which is meant to take velocity into account. Velocity tries to abstract away contextual factors like subreddit activity, number of votes, etc. and represent how quickly, relative to number of participants, a post is 'rising'. The 'top' algorithm, however, is purely a factor of total vote (up - down) + time.
      - ElvisMa 11y ago
        oh,... yes you are right :)
  - pacofvf 11y ago
    cpdef double _hot(long ups, long downs, double date): """The hot formula. Should match the equivalent function in postgres.""" s = score(ups, downs) order = log10(max(abs(s), 1)) if s > 0: sign = 1 elif s < 0: sign = -1 else: sign = 0 seconds = date - 1134028003 return round(sign * order + seconds / 45000, 7) here's the function in question, so yes a newer post with fewer votes than a minutes older post will remain on top.

Rifu 11y ago

I believe in this context it means that newer posts are ranked higher than older posts, which is pretty helpful in making sure the front page remains "fresh". [0] http://amix.dk/blog/post/19588 http://amix.dk/blog/post/19588 [1] http://www.outofscope.com/reddits-empire-no-longer-founded-on-a-flawed-algorithm/ http://www.outofscope.com/reddits-empire-no-longer-founded-o...

IanCal 11y ago

As I understand it, it is time-sensitive but indirectly. The number of votes compared to the age is important, but this isn't normalised compared to the current vote rate. There's a significant fluctuation in the number of people on reddit at different times of the day, so when you submit can be important.

jkyle 11y ago
This is absolutely correct. The algorithm is meant to quickly drop posts from the top. Such that even if a post has a record vote score, it still will only remain at the top for a few days. The amix link above didn't load for me today, but I like this scienceblogs post on the algorithm.[1] edit It should also be noted that since reddit is open source, you can always dig right in! [2] [1] http://scienceblogs.com/builtonfacts/2013/01/16/the-mathematics-of-reddit-rankings-or-how-upvotes-are-time-travel/ http://scienceblogs.com/builtonfacts/2013/01/16/the-mathemat... [2] https://github.com/reddit/reddit/blob/master/r2/r2/lib/db/_sorts.pyx https://github.com/reddit/reddit/blob/master/r2/r2/lib/db/_s...
- ElvisMa 11y ago
  not only that, the ranking is also defined by the overall activity in the sub-reddit it is posted in. So you can see a post with fewer upvotes, posted later over a post which has a lot more upvotes posted earlier. Which means, even submissions to very small sub-reddits have a decent chance to be promoted to trending and to r/all even
  - deleted 11y ago
    [deleted]
  - jkyle 11y ago
    The trending or 'hot' algorithm is a bit different than the "top" algorithm. I believe you're referring to the 'hot' algorithm which is meant to take velocity into account. Velocity tries to abstract away contextual factors like subreddit activity, number of votes, etc. and represent how quickly, relative to number of participants, a post is 'rising'. The 'top' algorithm, however, is purely a factor of total vote (up - down) + time.
    - ElvisMa 11y ago
      oh,... yes you are right :)
- pacofvf 11y ago
  cpdef double _hot(long ups, long downs, double date): """The hot formula. Should match the equivalent function in postgres.""" s = score(ups, downs) order = log10(max(abs(s), 1)) if s > 0: sign = 1 elif s < 0: sign = -1 else: sign = 0 seconds = date - 1134028003 return round(sign * order + seconds / 45000, 7) here's the function in question, so yes a newer post with fewer votes than a minutes older post will remain on top.