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https://github.com/bububa/timedecay
Famous sorting algorithms based on vote popularity and time implemented for go
https://github.com/bububa/timedecay
Last synced: about 5 hours ago
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Famous sorting algorithms based on vote popularity and time implemented for go
- Host: GitHub
- URL: https://github.com/bububa/timedecay
- Owner: bububa
- Created: 2021-03-10T05:33:38.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2021-03-10T05:36:42.000Z (over 3 years ago)
- Last Synced: 2024-06-19T14:57:06.164Z (5 months ago)
- Language: Go
- Size: 2.93 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# timedecay
sorting algorithms implemented for go, based heavily on the nodejs implementation of [https://github.com/clux/decay](https://github.com/clux/decay)
This library houses 3 popularity estimating algorithms employed by bigger news sites used to sort for best content:
1. `WilsonScore` - Reddit's _best_ comment scoring system
2. `RedditHot` - Reddit's _hot_ post scoring system for news posts
3. `HackerHot` - Hackernews' scoring system
## Usage
Decay exports 3 scoring function factories.
Two of these algorithms decay with time, and the other is based purely on statistical popularity.
### timedecay.NewWilsonScore(float64)
Non-decay based calculation based on statistical confidence of data.
```
import (
"github.com/bububa/timedecay"
)
func main() {
wilsonScore := timedecay.NewWilsonScore(1.96)
fmt.println(wilsonScore.Score(10, 3))
}
```
### timedecay.NewRedditHot(float64)
Popularity calcuation based on published Reddit rankings. [http://amix.dk/blog/post/19588](http://amix.dk/blog/post/19588)
```
import (
"time"
"github.com/bububa/timedecay"
)
func main() {
redditHot := timedecay.NewRedditHot(45000)
fmt.println(redditHot.Score(10, 3, time.now()))
}
```
### timedecay.NewHackerHot(float64)
Popularity calcuation based on published HackerNews rankings. [http://amix.dk/blog/post/19574](http://amix.dk/blog/post/19574)
```
import (
"time"
"github.com/bububa/timedecay"
)
func main() {
hackerHot := timedecay.NewHackerHot(1.9)
fmt.println(hackerHot.Score(10, 3, time.now()))
}
```
## Parameter Explanation
### 1. Wilson Score
AKA Reddit's *[Best](http://blog.reddit.com/2009/10/reddits-new-comment-sorting-system.html)* comment sorting system. [Source](https://github.com/reddit/reddit/blob/bd922104b971a5c6794b199f364a06fdf61359a2/r2/r2/lib/db/_sorts.pyx#L70-L85)
Statistically, it is the lower bound of the [Wilson Score interval](http://en.wikipedia.org/wiki/Binomial_proportion_confidence_interval) at the alpha level based on supplied Z score.
The optional `zScore` parameter can be passed as to the exported `wilsonScore` factory.
The Z score is a statistical value which roughly means how many standard deviations of safety you want, so it maps directly onto the confidence level of the Wilson Score interval.
It will default to `z=1.96` if left out, representing a `95%` confidence level in the lower bound. Otherwise, values through `1.0` (69%), to `3.3` (99.9%) good alternatives.
### 2. Reddit Hot Sort
Based on the difference between ups/downs, and decays with time. Causes hive mind effects in large crowds.
An optional _halflife_ parameter can be passed to the exported `redditHot` factory.
The half-life defaults to 45000 [s]. For info on the effects on this parameter read the original [blog post](https://medium.com/hacking-and-gonzo/how-reddit-ranking-algorithms-work-ef111e33d0d9) about it. See also the canonical [reddit source version](https://github.com/reddit/reddit/blob/bd922104b971a5c6794b199f364a06fdf61359a2/r2/r2/lib/db/_sorts.pyx#L47-L58).
### 3. HackerNews Hot Sort
Based on simply the amount of upvotes, and decays with time. Prone to advertising abuse.
An optional `gravity` parameter (defaulting to `1.8`) can be passed to the exported `hackerHot` factory. For info on the effects of this parameter read the original [blog post](https://medium.com/hacking-and-gonzo/how-hacker-news-ranking-algorithm-works-1d9b0cf2c08d) about it.
## Installation
```bash
$ go get -u github.com/bububa/timedecay
```
## License
MIT-Licensed. See LICENSE file for details.