Remove non-unique items from a dictionary, defining uniqueness only between a subset of keys

unique_dict_filtering.py

#!/usr/bin/env python

from itertools import imap, groupby
from operator import itemgetter


def unique_justseen(iterable, key=None):
    """List unique elements, preserving order.
    Remember only the element just seen."""

    # unique_justseen('AAAABBBCCDAABBB') --> A B C D A B
    # unique_justseen('ABBCcAD', str.lower) --> A B C A D
    return imap(next, imap(itemgetter(1), groupby(iterable, key)))



if __name__ == '__main__':

    print list(unique_justseen('AAAABBBCCDAABBB'))

    test = [
        {'a': 3, 'b': 4, 'c': 1},
        {'a': 3, 'b': 4, 'c': 2},
        {'a': 3, 'b': 4, 'c': 3},
        {'a': 3, 'b': 4, 'c': 4},
        {'a': 3, 'b': 4, 'c': 5},
        {'a': 3, 'b': 4, 'c': 6},
        {'a': 3, 'b': 4, 'c': 7}
    ]

    print list(unique_justseen(test, key=lambda x: (x['a'], x['b'])))