itertools.groupby

gistfile1.py

>>> from itertools import groupby
>>> data = [{'foo': 1, 'bar': 1, 'baz': 1}, {'foo': 1, 'bar': 1, 'baz': 2}, {'foo': 1, 'bar': 2, 'baz': 11}, {'foo': 1, 'bar': 2, 'baz': 12}, {'foo': 2, 'bar': 2, 'baz': 31}]
>>> for (key, group) in groupby(data, lambda x: [x[k] for k in ['foo', 'bar']]):
...     print 'keys'
...     print list(key)
...     print 'groups'
...     print list(group)
... 
keys
[1, 1]
groups
[{'baz': 1, 'foo': 1, 'bar': 1}, {'baz': 2, 'foo': 1, 'bar': 1}]
keys
[1, 2]
groups
[{'baz': 11, 'foo': 1, 'bar': 2}, {'baz': 12, 'foo': 1, 'bar': 2}]
keys
[2, 2]
groups
[{'baz': 31, 'foo': 2, 'bar': 2}]
>>>