Map elements from list with items from dictionary

I have a list of "important" checkpoints which are passed by a user:

important_checkpoints = ['checkpoint_1', 'checkpoint_2', 'checkpoint_3', 
                         'checkpoint_4', 'checkpoint_5']

The term "important" means, that from all possible checkpoints (‘checkpoint_1’, … ,checkpoint_99) the user can pass, I am only interested in the checkpoints listed in important_checkpoints.

Additionally I have a dictionary containing the checkpoints which have actually have been used by the users:

user_checkpoints = {"id_1": "checkpoint_11", "id_2": "checkpoint_3", "id_3": "checkpoint_4", 
                    "id_4": "checkpoint_45", "id_5": "checkpoint_68", "id_6": "checkpoint_1", 
                   "id_7": "checkpoint_1"}

Solution to example:
Now I want to get a dictionary which tells me which user-ID passed one of the "important" checkpoints:

{"checkpoint_1": [id_6, id_7], "checkpoint_2": [], "checkpoint_3": [id_2], "checkpoint_4": [id_3], 
"checkpoint_5": []}

My not finished solution
I was able to find passed important checkpoints (here: ['checkpoint_1', 'checkpoint_3', 'checkpoint_4']) but I was not able to match the corresponding IDs.

activated_checkpoints_by_user = [] # activated_forms_for_user_concerns
for key in important_checkpoints:
    if key in list(user_checkpoints.values()):
        activated_checkpoints_by_user.append(key) 

>> activated_checkpoints_by_user
>> ['checkpoint_1', 'checkpoint_3', 'checkpoint_4']

>Solution :

You basically want to map the values in the dictionary user_checkpoints back to the keys.
In Python there is no direct way to do it but you can itemize the dictionary and use a loop to get the result you want:

result_dict ={}
for imp_checkpoint in important_checkpoints:
  result_dict[imp_checkpoint]=[user_id for user_id, checkpoint in user_checkpoints.items() if checkpoint == imp_checkpoint]