class LowIpAlertController < ApplicationController

  def all_stats
    @all_stats = AutonomousSystem.all(:conditions => ['low_ip_alert_check = ?', true]).inject([]) do |list, autonomous_system|
      stats = LowIpAlertStat.new(autonomous_system)
      stats.send(:calculate)
      list << stats
    end

    csv_data = CSV.generate do |csv|
      csv << ["autonomous_system_name", "cidr", "percentage"]
      @all_stats.flat_map {|stat| stat.percentages_grouped_by_block.map {|key,value| [stat.autonomous_system.name,key,value] } }.each {|row| csv << row }
    end
    respond_to do |format|
      format.json {render :json => csv_data.to_json}
      format.csv { send_data (csv_data,
                              :type => 'text/csv; charset=utf-8; header=present',
                              :disposition => "attachment",
                              :filename => "lowIpAlert.csv")}
    end
  end

end
desired output:

autonomous_system_name   cider                    percentage
DFW                      166.78.42.0/23            100
DFW                      166.78.33.0/24            100
DFW                      209.61.129.0/24           100.0
DFW                      166.78.36.0/22            99.21875

input :
@all_stats =
[#<LowIpAlertStat:0x7f5af0527cc0
  @autonomous_system=
   #<AutonomousSystem id: 11, name: "DFW", number: 33070, description: "DFW", created_at: nil, updated_at: "2013-09-04 19:30:06", owner_number: "DCO1", private: false, autonomous_system_id: nil, network_environment_id: 55, low_ip_alert_check: true, low_ip_alert_threshold: 70>,
 @percentages_grouped_by_block=
   {"166.78.42.0/23"=>100.0,
    "166.78.33.0/24"=>100.0,
    "209.61.129.0/24"=>100.0,
    "166.78.36.0/22"=>99.21875,
    "166.78.32.0/24"=>100.0,
    "209.61.131.0/24"=>100.0,
    "209.61.128.0/24"=>100.0,
    "50.56.228.0/24"=>100.0},>]
=>nil

controller: