有没有办法将字典列表转换为一组字典？

Question

I'd like to convert a list of dicts into a set of dicts.

For example:

I have the following list:

my_list = [{k1:v1, k2:v2}, {k3:v3, k4:v4}]

I simply want to convert it easily to a set of these dicts.

As long as my lists were holding simple data like Strings, there was no problem with:

new_list = set(myList)

But if they hold dicts, they fall on

TypeError: unhashable type: 'dict'

I'd rather not iterating the list and add each item to the set. I'd rather have a straight forward method which will also support list of strings for example.

Is that possible?

Answer 1

As the error suggests elements in a set must be hashable, which means that the must have a unique id (given by the hash method ). You could create your own dict extension class that gives the dict a hash, eg the hash of all its keys. Or test/filter your list before converting it to a set. In short, a set cannot contain dicts.

Answer 2

Python doesn't have a builtin 'frozendict' type. If you really want to emulate what a frozendict would do, then you might want to to store a hashable equivalent of a dict. For example:

my_list = [{k1:v1, k2:v2}, {k3:v3, k4:v4}]

my_set = set(frozenset(d.items()) for d in my_lst)

If you want to get your dicts back all you need to do is:

my_list = list(map(dict, my_set))