Python: finding keys with unique values in a dictionary?

Question

I receive a dictionary as input, and want to return a list of keys for which the dictionary values are unique in the scope of that dictionary.

I will clarify with an exa

Answer 1

You could do something like this (just count the number of occurrences for each value):

def unique(a):
    from collections import defaultdict
    count = defaultdict(lambda: 0)
    for k, v in a.iteritems():
        count[v] += 1
    for v, c in count.iteritems():
        if c <= 1:
            yield v