GitHub repositories ranking algorithm (based on HN ranking algorithm)

github-repo-ranking.rb

# Inspired by Hacker News ranking algorithm
# http://www.righto.com/2013/11/how-hacker-news-ranking-really-works.html

require 'json'
require 'ostruct'
require 'time'
require 'open-uri'

FORKS_FACTOR = 1.7
STARGAZERS_FACTOR = 1.5
OPEN_ISSUES_FACTOR = 1.3
FORK_FACTOR = 0.5

GRAVITY = 1.8

pretty_print = -> (repo) {
  puts "#{repo.name}: #{repo.rating} (forks: #{repo.forks_count}, stargazers: #{repo.stargazers_count}, issues: #{repo.open_issues_count}, fork: #{repo.fork})"
}

json = URI.parse('https://api.github.com/users/soulim/repos?per_page=100').read

# repos = JSON.parse(File.read('./repos.json')).map do |repo|
repos = JSON.parse(json).map do |repo|
  OpenStruct.new(repo).tap do |repo|
    repo.pushed_at = Time.parse(repo.pushed_at)
    repo.created_at = Time.parse(repo.created_at)
    repo.updated_at = Time.parse(repo.updated_at)

    repo.rating = begin
      rating = 0.0
      rating = repo.forks_count * FORKS_FACTOR
      rating += repo.stargazers_count * STARGAZERS_FACTOR
      rating += repo.open_issues_count * OPEN_ISSUES_FACTOR
      if repo.fork
        rating *= FORK_FACTOR
      end
      rating /= ((Time.now.to_i - repo.pushed_at.to_i)/3600)**GRAVITY

      rating
    end
  end
end

puts '# Unordered'
puts ''

repos.each { |repo| pretty_print.call(repo) }

puts ''
puts '# Ordered by rating'
puts ''

repos.sort_by(&:rating).reverse.each { |repo| pretty_print.call(repo) }