Excel / SpreedSheet column notation calculator in ruby

excel_spreedsheet_column_notation_calculator

#!/usr/bin/env ruby

module Spreedsheet
  module ColumnNotation
    def seed
      @seed ||= ('A'..'Z').to_a
    end

    def position_to_column_notation(num, minus = 0)
      m = num.divmod(seed.size)
      if m.first > 0
        extr = ''
        extr = position_to_column_notation(m.first, 1) if m.first > seed.size
        [extr, seed[m.first - 1], seed[m.last - minus]].join('')
      else
        seed[m.last]
      end
    end

    def column_notation_to_position(str_param)
      str = str_param.reverse
      val = 0
      str.split('').each_with_index do |item, pwr|
        power      = pwr > 1 ? pwr : 1
        plus       = pwr == 0 ? 0 : 1
        multiplier = pwr == 0 ? 1 : seed.size
        val += ( (seed.index(item) + plus) * multiplier ** power )
      end
      val
    end
  end
end

class A
  include Spreedsheet::ColumnNotation
end

a = A.new

[0, 24, 25, 26, 700, 701, 702, 703, 18276, 18277, 18278].each do |i|
  print "#{i} -> "
  puts a.position_to_column_notation i
end

[ 'A', 'Y', 'Z', 'AA', 'ZY', 'ZZ','AAA','AAB','ZZY','ZZZ','AAAA' ].each do |i|
  print "#{i} -> "
  puts a.column_notation_to_position i
end

__END__

$ ruby excel_spreedsheet_column_notation_calculator.rb 
0 -> A
24 -> Y
25 -> Z
26 -> AA
700 -> ZY
701 -> ZZ
702 -> AAA
703 -> AAB
18276 -> AAZY
18277 -> AAZZ
18278 -> AAAA
A -> 0
Y -> 24
Z -> 25
AA -> 26
ZY -> 700
ZZ -> 701
AAA -> 702
AAB -> 703
ZZY -> 18276
ZZZ -> 18277
AAAA -> 18278