Generate a pie chart showing commits by author in a git repository

commit.rb

#!/usr/bin/ruby

# Run in the root directory of a git repository with ruby commits.rb
# Depends upon the 'rmagic' and 'gruff' gems.

require 'rubygems'
require 'gruff'

commits = `git shortlog -ns`.split("\n").map { |e| e.strip.split("\t") }.map { |n, a| [a, n.to_i] }

module Gruff
  class Base
    def label(value)
      label = if @marker_count.to_f == 0
                value.to_i.to_s
              elsif ((@spread.to_f % @marker_count.to_f == 0) ||
                     !@y_axis_increment.nil?)
                value.to_i.to_s
              elsif @spread > 10.0
                sprintf("%0i", value)
              elsif @spread >= 3.0
                sprintf("%0.2f", value)
              else
                value.to_s
              end

      parts = label.split('.')
      parts[0].gsub!(/(\d)(?=(\d\d\d)+(?!\d))/, "\\1#{THOUSAND_SEPARATOR}")
      parts.join('.')
    end
  end
end

g = Gruff::Pie.new
g.title = "Git commits by author"
commits.each { |a, n| g.data(a, n) }
g.write("commits.png")