3 ms·
Is it hot or not? Ranking of user modded content.
Reddit and News.YC share a feature: hotness. Users mod up and down -- but hotness is more than total points.
How should I do it?
Positive correlation with number of votes.
Negative correlation with submit time.
Perhaps negative correlation with time since mean or median time of mods.
Perhaps adjust for rates -- a surge implies extra hotness.
How do you make the front page efficiently? I hope not to recalculate hotness for each page view -- but a naive approach might think it necessary given the continuous time decay.
A parallel service could periodically troll through the entries from the past N days and calculate their hotness -- which serves the front page. That could be updated and chached in memory inependent of front pageview count.
- pg 19y agoThe way I do it is points divided by age in hours (plus two) to the 1.25th power. This is probably not optimal, but it's simple. (= gravity* 1.25 timebase* 120) (def hotness (s (o gravity gravity*)) (/ (- (realscore s) 1) (expt (/ (+ (story-age s) timebase*) 60) gravity))) I avoid reranking all the stories by keeping them in sorted order, and whenever I generate a frontpage for someone logged in, reinserting one randomly chosen story near the top (where all the change is). I also reinsert any story that gets voted on.
- ivankirigin 19y agoInteresting. Right now, I have no data, making testing difficult -- especially for anything that will change hotness depending on distribution of mods in a given time. It's been something I've been thinking about for a bit, and want to get it out of my head to focus on building something that people use so I can actually get the data.
- darragjm 19y agoWhy not just start with a simple hotness algorithm and evolve it after data starts coming in?
- ivankirigin 19y agoThat's exactly what I'll do.
- run4yourlives 19y agoThanks for sharing that Paul. Most people guard that knowledge like it's the lost grail. Kudo to you for being open about it.
- ivankirigin 19y agoIndeed
- palish 19y agoSpeaking of karma, I wrote a little micro-essay about it at http://news.ycombinator.com/item?id=38605 http://news.ycombinator.com/item?id=38605 .. I don't know if you'd want to experiment with karma quite like that, but it would be interesting.