google_charts_data_encoding.rb

    def extended_encode(data_arr, max_value)
      # Douglas F Shearer 2007
      # http://douglasfshearer.com/blog/ruby-google-charts-api-data-encoding
      characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-.'.split(//)
      data = ''
      data_arr.each do |value|
        if value.is_a?(Integer) && value >= 0
          new_value = ((4095 * value.to_f / max_value.to_f).to_i)
          sixtyfours = new_value/64
          units = new_value%64
          p '64:' + sixtyfours.to_s
          p 'units: ' + units.to_s
          data << characters[sixtyfours] + characters[units]
        else
          data << '__'
        end
      end
      data
    end