# File lib/ruport/data/grouping.rb, line 163
    def initialize(data={},options={})
      if data.kind_of?(Hash)
        @grouped_by = data[:by]
        @order = data[:order] 
        @data = {}
      else
        @grouped_by = options[:by]    
        @order = options[:order]
        cols = Array(options[:by]).dup
        @data = data.to_group.send(:grouped_data, cols.shift)
        cols.each do |col|
          @data.each do |name,group|
            group.create_subgroups(col)
          end
        end    
      end
    end