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In questo tutorial, abbiamo costruito un modello a matrice fattorizzazione semplice utilizzando il set di dati MovieLens 100K con TFRs. Possiamo usare questo modello per consigliare film per un determinato utente.
Importa TFRS
Innanzitutto, installa e importa TFRS:
pip install -q tensorflow-recommenderspip install -q --upgrade tensorflow-datasets
from typing import Dict, Text
import numpy as np
import tensorflow as tf
import tensorflow_datasets as tfds
import tensorflow_recommenders as tfrs
Leggi i dati
# Ratings data.
ratings = tfds.load('movielens/100k-ratings', split="train")
# Features of all the available movies.
movies = tfds.load('movielens/100k-movies', split="train")
# Select the basic features.
ratings = ratings.map(lambda x: {
"movie_title": x["movie_title"],
"user_id": x["user_id"]
})
movies = movies.map(lambda x: x["movie_title"])
2021-10-02 12:07:32.719766: E tensorflow/stream_executor/cuda/cuda_driver.cc:271] failed call to cuInit: CUDA_ERROR_NO_DEVICE: no CUDA-capable device is detected
Crea vocabolari per convertire gli ID utente e i titoli dei film in indici interi per incorporare i livelli:
user_ids_vocabulary = tf.keras.layers.StringLookup(mask_token=None)
user_ids_vocabulary.adapt(ratings.map(lambda x: x["user_id"]))
movie_titles_vocabulary = tf.keras.layers.StringLookup(mask_token=None)
movie_titles_vocabulary.adapt(movies)
Definire un modello
Possiamo definire un modello TFRs ereditando dalla tfrs.Model e attuare il compute_loss metodo:
class MovieLensModel(tfrs.Model):
# We derive from a custom base class to help reduce boilerplate. Under the hood,
# these are still plain Keras Models.
def __init__(
self,
user_model: tf.keras.Model,
movie_model: tf.keras.Model,
task: tfrs.tasks.Retrieval):
super().__init__()
# Set up user and movie representations.
self.user_model = user_model
self.movie_model = movie_model
# Set up a retrieval task.
self.task = task
def compute_loss(self, features: Dict[Text, tf.Tensor], training=False) -> tf.Tensor:
# Define how the loss is computed.
user_embeddings = self.user_model(features["user_id"])
movie_embeddings = self.movie_model(features["movie_title"])
return self.task(user_embeddings, movie_embeddings)
Definire i due modelli e l'attività di recupero.
# Define user and movie models.
user_model = tf.keras.Sequential([
user_ids_vocabulary,
tf.keras.layers.Embedding(user_ids_vocabulary.vocab_size(), 64)
])
movie_model = tf.keras.Sequential([
movie_titles_vocabulary,
tf.keras.layers.Embedding(movie_titles_vocabulary.vocab_size(), 64)
])
# Define your objectives.
task = tfrs.tasks.Retrieval(metrics=tfrs.metrics.FactorizedTopK(
movies.batch(128).map(movie_model)
)
)
WARNING:tensorflow:vocab_size is deprecated, please use vocabulary_size. WARNING:tensorflow:vocab_size is deprecated, please use vocabulary_size. WARNING:tensorflow:vocab_size is deprecated, please use vocabulary_size. WARNING:tensorflow:vocab_size is deprecated, please use vocabulary_size.
Adattalo e valutalo.
Crea il modello, addestralo e genera previsioni:
# Create a retrieval model.
model = MovieLensModel(user_model, movie_model, task)
model.compile(optimizer=tf.keras.optimizers.Adagrad(0.5))
# Train for 3 epochs.
model.fit(ratings.batch(4096), epochs=3)
# Use brute-force search to set up retrieval using the trained representations.
index = tfrs.layers.factorized_top_k.BruteForce(model.user_model)
index.index_from_dataset(
movies.batch(100).map(lambda title: (title, model.movie_model(title))))
# Get some recommendations.
_, titles = index(np.array(["42"]))
print(f"Top 3 recommendations for user 42: {titles[0, :3]}")
Epoch 1/3 25/25 [==============================] - 6s 194ms/step - factorized_top_k/top_1_categorical_accuracy: 3.0000e-05 - factorized_top_k/top_5_categorical_accuracy: 0.0016 - factorized_top_k/top_10_categorical_accuracy: 0.0052 - factorized_top_k/top_50_categorical_accuracy: 0.0442 - factorized_top_k/top_100_categorical_accuracy: 0.1010 - loss: 33092.9163 - regularization_loss: 0.0000e+00 - total_loss: 33092.9163 Epoch 2/3 25/25 [==============================] - 5s 194ms/step - factorized_top_k/top_1_categorical_accuracy: 1.7000e-04 - factorized_top_k/top_5_categorical_accuracy: 0.0052 - factorized_top_k/top_10_categorical_accuracy: 0.0148 - factorized_top_k/top_50_categorical_accuracy: 0.1054 - factorized_top_k/top_100_categorical_accuracy: 0.2114 - loss: 31008.8447 - regularization_loss: 0.0000e+00 - total_loss: 31008.8447 Epoch 3/3 25/25 [==============================] - 5s 193ms/step - factorized_top_k/top_1_categorical_accuracy: 3.4000e-04 - factorized_top_k/top_5_categorical_accuracy: 0.0086 - factorized_top_k/top_10_categorical_accuracy: 0.0222 - factorized_top_k/top_50_categorical_accuracy: 0.1438 - factorized_top_k/top_100_categorical_accuracy: 0.2694 - loss: 30417.8776 - regularization_loss: 0.0000e+00 - total_loss: 30417.8776 Top 3 recommendations for user 42: [b'Rent-a-Kid (1995)' b'Just Cause (1995)' b'Land Before Time III: The Time of the Great Giving (1995) (V)']