another_test_hash.rb

# Entering in tabs as \t so that it's easier to understand where the tab
mybuffer = "1\tabc\txyz\tjan1
 \tdef\tlmn\tfeb1
2\tamy\tmorgan\tmay1
 \tnick\tcary\tmay6"
test_hash = {}
gid = ""
#Split on new line so each line
mybuffer.split(/\n/).each do |line|
  #split the line on the \t (tab) character so that we have 4 columns (groupid, first name, last name, birthday)
  columns = line.split(/\t/)
  # if the first column (group id) is just an empty space then set the gid to the existing group id
  if columns.first == " "
    gid = gid
  else # else set the gid to the first column (gid)
    gid = columns.first
  end
  # if the hash has an item with a key of the group id
  if test_hash[gid]
    # add another person to the array
    test_hash[gid] << {:fname=>columns[1],:lname=>columns[2],:bday=>columns.last}
  else
    # create a hash item in which the contents is an array with one person in it
    test_hash[gid] = [{:fname=>columns[1],:lname=>columns[2],:bday=>columns.last}]
  end
end

puts test_hash.inspect
#{"1"=>[{:bday=>"jan1", :fname=>"abc", :lname=>"xyz"}, {:bday=>"feb1", :fname=>"def", :lname=>"lmn"}], 
# "2"=>[{:bday=>"may1", :fname=>"amy", :lname=>"morgan"}, {:bday=>"may6", :fname=>"nick", :lname=>"cary"}]}