#! /usr/bin/env python
# -*- coding: utf-8 -*-

import operator, itertools

my_list = [ { "a": 1, "b": 1, "c": 3 },
            { "a": 1, "b": 1, "c": 4 },
            { "a": 1, "b": 11, "c": 3 },
            { "a": 1, "b": 11, "c": 4 },
            { "a": 2, "b": 1, "c": 3 },
            { "a": 2, "b": 1, "c": 4 },
            { "a": 2, "b": 11, "c": 3 },
            { "a": 2, "b": 11, "c": 4 }  ]

# group my_list by "a"
my_list.sort( key=operator.itemgetter('a') )
my_list_grouped = itertools.groupby( my_list, operator.itemgetter('a') )
my_list_grouped = list( my_list_grouped )

for k in [ 'first pass', 'second pass' ]:
    print k

    for my_item in my_list_grouped:
        print "\t" + str( my_item[0] )

        # group by keyword "b"; need to get list first to be able to use 'sort'
        my_list2 = list( my_item[1] )
        my_list2.sort( key=operator.itemgetter('b') )
        my_list_grouped = itertools.groupby( my_list2, operator.itemgetter('b') )

        for e in my_list_grouped:
            print "\t\t" + str( e[0] )
            lll = list( e[1] )
            for ee in lll:
                print "\t\t\t" + str( ee )