unique (single) value in dict (or list)

[deanhystad]

Like this?

items1 = {1:1, 2:2, 3:3}
items2 = {1:1, 2:1, 3:2, 4:2, 5:3}
items3 = {1:1, 2:1, 3:3, 4:5, 5:4}

def find_unique(d):
    value_list = list(d.values())
    value_set = set(value_list)
    if len(value_set) == len(value_list):
        return None # All values are unique

    unique = None
    for value in value_set:
        if value_list.count(value) == 1:
            if unique is None:
                unique = value
            else:
                return None # Already found a unique value
    return unique

print(items1, '  Unique =', find_unique(items1))
print(items2, '  Unique =', find_unique(items2))
print(items3, '  Unique =', find_unique(items3))

Output:
{1: 1, 2: 2, 3: 3}   Unique = None
{1: 1, 2: 1, 3: 2, 4: 2, 5: 3}   Unique = 3
{1: 1, 2: 1, 3: 3, 4: 5, 5: 4}   Unique = None