Check if list of dictionaries are unique based on a property

Question

Is there a function in the python standard library to check if a list is unique based on one of the dictionary properties?

Something like this:

is_unique(dict_list, prop="x")

result:

{"x": 1, "y": 2}, {"x": 2, "y": 2}, {"x": 2, "y": 3}  <- False
{"x": 1, "y": 2}, {"x": 2, "y": 2}, {"x": 3, "y": 3}  <- True

Answer 1

You can naively do:

def is_unique(dcts, prop):
    return len(dcts) == len(set(d[prop] for d in dcts))

This assumes that the values d[prop] are hashable. If you have long lists, you might want to break early (when encountering the first duplicate) while building the prop set, as does U9-Forward's solution.