How to convert list of lists to a set in python so I can compare to other sets?

Question

I have a list users_with_invites_ids_list, formed by loop where I append values to the list, in python that looks like this:

...[ObjectId('55119e14bf2e4e010d8b48f2')], [ObjectId('54624128bf2e4e5e558b5a52')], [ObjectId('53a6e7bc763f4aa0308b4569')], [ObjectId('55241823bf2e4e59508b494c')]]

when I try:

    users_with_invites_ids_set = set(users_with_invites_ids_list)

I get:

TypeError: unhashable type: 'list'

How do I convert this list of lists to a set?

EDIT

based on answer I've done the following:

#convert list to set
first_tuple_list = [tuple(lst) for lst in users_with_invites_ids_list]
users_with_invites_ids_set = set(first_tuple_list)

Which yields the following:

 (ObjectId('542ac5a6763f4a82188b4a51'),), (ObjectId('54496fe6bf2e4efe348bd344'),), (ObjectId('54c96339bf2e4ee62c8b48e0'),)])

How do I get each ObjectId without the () around each one. It's keeping me from comparing this set to other set's of ids.

Answer 1

You would need to convert the inner lists to tuples, assuming each of those ObjectId('55119e14bf2e4e010d8b48f2') is hashable:

users_with_invites_ids_set = set(tuple(x) for x in users_with_invites_ids_list)

---

Working example:

>>> class ObjectId(object):
...   def __init__(self, v):
...     self.v = v
... 
>>> list_of_lists = [[ObjectId('55119e14bf2e4e010d8b48f2')], [ObjectId('54624128bf2e4e5e558b5a52')], [ObjectId('53a6e7bc763f4aa0308b4569')], [ObjectId('55241823bf2e4e59508b494c')]]
>>> set(tuple(x) for x in list_of_lists)
set([(<__main__.ObjectId object at 0x7f71483cfc50>,), (<__main__.ObjectId object at 0x7f71483cfd10>,), (<__main__.ObjectId object at 0x7f71483cfcd0>,), (<__main__.ObjectId object at 0x7f71483cfc90>,)])

---

In case if you are looking to create the set of the ObjectId's alone, you could do:

>>> set(x for lst in list_of_lists for x in lst)
set([<__main__.ObjectId object at 0x7f71483cfb10>, <__main__.ObjectId object at 0x7f71483db050>, <__main__.ObjectId object at 0x7f71483cfad0>, <__main__.ObjectId object at 0x7f71483cfd50>])

Answer 2

In case list of lists has lists of integer, you can use this function to convert it to set of one list :

outer_list = [] 
def lists_to_list(nested_lists): 
    for el in nested_lists: 
        if type(el) == list: 
            lists_to_list(el) 
        else: 
            outer_list.append(el)
    return set(outer_list)

Example:

nested_list = [[7, 7], [2, 3, 3, 0], [9, 1, 9, 1]]
print(lists_to_list(nested_list))

Output:

{0, 1, 2, 3, 7, 9}