Small script to gather some stats about a project's volatility between releases

project-stats.rb

def info(prev_tag, tag)
  `git checkout -q #{tag}`
  diffstat = `git diff --stat #{prev_tag} #{tag} ./lib`.split(/\n/)[-1]

  insertions = /(\d+) insertions/.match(diffstat)[1].to_i rescue 0
  deletions = /(\d+) deletions/.match(diffstat)[1].to_i rescue 0
  sloc = /ruby=(\d+)/m.match(`sloccount lib`)[1].to_i
  changes = insertions+deletions
  changetrate = changes.to_f/sloc
  {
    :tag => tag,
    :insertions => insertions,
    :deletions => deletions,
    :sloc => sloc,
    :changetrate => changetrate
  }
end

puts "TAG\tCHANGE RATE %\tSLOC\tINSERTIONS\tDELETIONS"

tags = `git tag | sort --version-sort`.split(/\n/)
prev_tag = tags[0]
tags[1..-1].each do |tag|
  info = info(prev_tag, tag)
  puts sprintf("%s\t%f\t%d\t%d\t%d", info[:tag], info[:changetrate]*100, info[:sloc], info[:insertions], info[:deletions])
  prev_tag = tag
end