[Tutor] generating unique set of dicts from a list of dicts

[Peter Otten]

[NN]
>> uniques_map = {}
>> for d in list_of_dicts:
>>      uniques[dict_hash(d)] = d
>> unique_dicts = uniques_map.values()

[Dave Angel] 
> unique_dicts = []
> for d in list_of_dicts:
>       if d not in unique_dicts:
>             unique_dicts.append(d)
> 
> Do it, then decide if performance is inadequate.  Only then  should you
> worry about faster methods, especially if the faster method is broken.

Another variant:

# keys and values in the dictionaries must be hashable
list_of_dicts = ...

unique_dicts_map = {}
for d in list_of_dicts:
    key = frozenset(d.items())
    unique_dicts_map[key] = d 

unique_dicts = unique_dicts_map.values()

I'm using a frozenset because it is hashable. It should be easy to see that 
two dicts are equal if and only if they comprise a set of equal key-value 
pairs.