Vfrdtyky

users = {'196': ('110', '1'), '186': ('269', '1'), '22': ('68', '4'), '196': ('650', '3')}

movies = {'110': 'Operation Dumbo Drop (1995)', '186': 'Blues Brothers, The (1980)',  '269': 'Full Monty, The (1997)', '68': 'Crow, The (1994)', '650': 'Seventh Seal, The (Sjunde inseglet, Det) (1957)'}

My code to create a nested dictionary with keys a unique list of users (keys from users) but using keys from movies to replace values of movies IDs (first item of value list from users) and keeping scores (second item of value list from users) is:

users_preference = {k: list(set().union((*map(lambda x: [x for x in movies.values()], v[0])) )) for k, v in users.items() }

But this returns all movies for each user, and I don't know how to add scores to this. Could you please help? Thank you.

The expected output is similar to:

users_preference = {'196': {'Operation Dumbo Drop (1995)': '1', 'Seventh Seal, The (Sjunde inseglet, Det) (1957)': '3'}

The expected output cannot be achieved using the format of users, I suggest you change to a dictionary where the values are a list of tuples:

users = {'196': [('110', '1'), ('650', '3')], '186': [('269', '1')], '22': [('68', '4')]}

movies = {'110': 'Operation Dumbo Drop (1995)', '186': 'Blues Brothers, The (1980)', '269': 'Full Monty, The (1997)',

          '68': 'Crow, The (1994)', '650': 'Seventh Seal, The (Sjunde inseglet, Det) (1957)'}



user_preference = {user: {movies.get(movie, movie): rank for movie, rank in preferences} for user, preferences in

                   users.items()}



print(user_preference)

Output

{'196': {'Operation Dumbo Drop (1995)': '1', 'Seventh Seal, The (Sjunde inseglet, Det) (1957)': '3'}, '22': {'Crow, The (1994)': '4'}, '186': {'Full Monty, The (1997)': '1'}}

Dct3 = {k:(movies[v[0]],v[1]) for k, v in users.items()}

Keep it simple, you can use keys to access values from movies dict.
Just think of it as creating a new tuple as values for each key in users.

More verbose

Dct3 = {}

for k, v in users.items():

  v = list(v)

  v[0] = movies[v[0]]

  Dct3[k] = v



print (Dct3)

#=> {'196': ['Seventh Seal, The (Sjunde inseglet, Det) (1957)', '3'], '186': ['Full Monty, The (1997)', '1'], '22': ['Crow, The (1994)', '4']}

You can issue

{user:(movies[movie_id], score) for user, (movie_id, score) in users.items()}

which produces

{'186': ('Full Monty, The (1997)', '1'),

 '196': ('Seventh Seal, The (Sjunde inseglet, Det) (1957)', '3'),

 '22': ('Crow, The (1994)', '4')}

Note that there is a duplicate key in your dictionary users ('196'). (Pointed out by Daniel Mesejo in the comments.) Dictionary keys must be unique, so users actually looks like this:

>>> users

>>> {'186': ('269', '1'), '196': ('650', '3'), '22': ('68', '4')}

~edit~

Traditional for loop that does the same.

result = {}

for user, (movie_id, score) in users.items():

    result[user] = (movies[movie_id], score)