Predicting movie ratings for users
To predict how we might rate a particular movie, we can compute a weighted average of critics who have also rated the same movies as the user. The weight will be the similarity of the critic to the user if a critic has not rated a movie, then their similarity will not contribute to the overall ranking of the movie.
Getting ready
Ensure that you have completed the previous recipes in this large, cumulative chapter.
How to do it...
The following steps walk you through the prediction of movie ratings for users:
- First, add the
predict_rankingfunction to theMovieLensclass in order to predict the ranking that a user might give a particular movie with similar critics:
In [17]: def predict_ranking(self, user, movie, metric='euclidean', critics=None):
...: """
...: Predicts the ranking a user might give a movie according to the
...: weighted average of the critics that are similar to the that user.
...: """
...:
...: critics = critics or self.similar_critics(user...
