get_maximum_by_stack (Gruff::Base)

    # File lib/gruff/base.rb, line 956
        def get_maximum_by_stack
          # Get sum of each stack
          max_hash = {}
          @data.each do |data_set|
            data_set[DATA_VALUES_INDEX].each_with_index do |data_point, i|
              max_hash[i] = 0.0 unless max_hash[i]
              max_hash[i] += data_point.to_f
            end
          end

          # @maximum_value = 0
          max_hash.keys.each do |key|
            @maximum_value = max_hash[key] if max_hash[key] > @maximum_value
          end
          @minimum_value = 0
        end