hash_test.rb

#this is your output buffer simulated in a hash
mybuffer = {"1"=>[{:parser_first_name=>"abc",:parser_last_name=>"xyz",:parser_bday=>"jan1"},
                {:parser_first_name=>"def",:parser_last_name=>"lmn",:parser_bday=>"feb1"}],
            "2"=>[{:parser_first_name=>"amy",:parser_last_name=>"morgan",:parser_bday=>"may1"},
                {:parser_first_name=>"nick",:parser_last_name=>"cary",:parser_bday=>"may6"}]
           }
test_hash = {}
mybuffer.each do |groupid,people|
  people.each do |person|
    # if there is an group with that id in  the hash already
    if test_hash[groupid] 
      # add another "person" into the list of people (or another item in the array)
      test_hash[groupid] << {:fname=>person[:parser_first_name],:lname=>person[:parser_last_name],:bday=>person[:parser_bday]} 
    else # if there isn't a group with that id in the hash already
      # create a group in the hash with a key of the group id and the contents is list of people containing one person (an array containing one hash)
      test_hash[groupid] = [{:fname=>person[:parser_first_name],:lname=>person[:parser_last_name],:bday=>person[:parser_bday]}]
    end
  end
end

puts test_hash.inspect
puts "\n\nNow you can do stuff like this:"
test_hash.each do |gid,people|
  people.each do |person|
    puts "#{person[:fname]} #{person[:lname]} who's birthday is #{person[:bday]} is in group #{gid}"
  end
end