gistfile1.rb

# -*- encoding: utf-8 -*-
require "rexml/document"
doc = nil
filename = ARGV[0]
if ARGV.size == 0
  puts "usage: ruby kaken.rb filename"
  exit
end

File.open(filename) {|fp|
    doc = REXML::Document.new fp
}

h = Hash.new
h.default = 0

i = 0
doc.root.elements.each {|e|
  d = REXML::XPath.first(e,"date")
  next if d == nil
  f = REXML::XPath.first(d,"from")
  next if f == nil
  year = f.text.to_i
  h[year] = h[year] + 1
}

h.to_a.sort{|a,b| (a[0] <=> b[0])}.each{|a|
  puts "#{a[0]} #{a[1]}"
}