csv diffing

gistfile1.rb

#!/usr/bin/env ruby

# task of this script is
# calculate diff

class CSV
  def initialize filename
    @filename = filename
    @f = File.open(@filename)
    @data = []
    @diff_map = []
  end

  def read_line
    @f.gets
  end

  def parse_line
    line = read_line
    return nil unless line
    ary = line.strip.split(",").map{|str| str.to_i}
    return ary
  end

  def parse
    while ary = parse_line
      @data << ary
    end
  end

  def array_diff ary0, ary1
    len = ary0.length > ary1.length ? ary0.length : ary1.length
    ary = []
    0.upto(len - 1) do |n|
      base0 = ary0[n] || 0
      base1 = ary1[n] || 0
      ary << (base0 - base1)
    end

    return ary
  end

  def get_diff
    return @diff_map unless @diff_map.empty?
    parse
    0.upto (@data.length - 2) do |n|
      @diff_map << array_diff(@data[n+1], @data[n])
    end
    return @diff_map
  end

  def print_diff
    diffary = get_diff
    diffary.each do |ent|
      ent.each do |elm|
        printf "#{elm},"
      end
      printf "\n"
      STDOUT.flush
    end
  end
end

csv = CSV.new ARGV.shift
csv.print_diff