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activation=\"relu\",
name=\"process_movie_embedding_with_genres\",
)
## Define a function to encode a given movie id.
def encode_movie(movie_id):
# Convert the string input values into integer indices.
movie_idx = movie_index_lookup(movie_id)
movie_embedding = movie_embedding_encoder(movie_idx)
encoded_movie = movie_embedding
if include_movie_features:
movie_genres_vector = movie_genres_lookup(movie_idx)
encoded_movie = movie_embedding_processor(
layers.concatenate([movie_embedding, movie_genres_vector])
)
return encoded_movie
## Encoding target_movie_id
target_movie_id = inputs[\"target_movie_id\"]
encoded_target_movie = encode_movie(target_movie_id)
## Encoding sequence movie_ids.
sequence_movies_ids = inputs[\"sequence_movie_ids\"]
encoded_sequence_movies = encode_movie(sequence_movies_ids)
# Create positional embedding.
position_embedding_encoder = layers.Embedding(
input_dim=sequence_length,
output_dim=movie_embedding_dims,
name=\"position_embedding\",
)
positions = tf.range(start=0, limit=sequence_length - 1, delta=1)
encodded_positions = position_embedding_encoder(positions)
# Retrieve sequence ratings to incorporate them into the encoding of the movie.
sequence_ratings = tf.expand_dims(inputs[\"sequence_ratings\"], -1)
# Add the positional encoding to the movie encodings and multiply them by rating.
encoded_sequence_movies_with_poistion_and_rating = layers.Multiply()(
[(encoded_sequence_movies + encodded_positions), sequence_ratings]
)
# Construct the transformer inputs.
for encoded_movie in tf.unstack(
encoded_sequence_movies_with_poistion_and_rating, axis=1
):
encoded_transformer_features.append(tf.expand_dims(encoded_movie, 1))
encoded_transformer_features.append(encoded_target_movie)
encoded_transformer_features = layers.concatenate(
encoded_transformer_features, axis=1
)
return encoded_transformer_features, encoded_other_features
Create a BST model
include_user_id = False
include_user_features = False
include_movie_features = False
hidden_units = [256, 128]
dropout_rate = 0.1
num_heads = 3
def create_model():
inputs = create_model_inputs()
transformer_features, other_features = encode_input_features(
inputs, include_user_id, include_user_features, include_movie_features
)
# Create a multi-headed attention layer.
attention_output = layers.MultiHeadAttention(
num_heads=num_heads, key_dim=transformer_features.shape[2], dropout=dropout_rate
)(transformer_features, transformer_features)
# Transformer block.
attention_output = layers.Dropout(dropout_rate)(attention_output)
x1 = layers.Add()([transformer_features, attention_output])
x1 = layers.LayerNormalization()(x1)
x2 = layers.LeakyReLU()(x1)
x2 = layers.Dense(units=x2.shape[-1])(x2)
x2 = layers.Dropout(dropout_rate)(x2)
transformer_features = layers.Add()([x1, x2])
transformer_features = layers.LayerNormalization()(transformer_features)
features = layers.Flatten()(transformer_features)
# Included the other features.
if other_features is not None:
features = layers.concatenate(
[features, layers.Reshape([other_features.shape[-1]])(other_features)]
)
# Fully-connected layers.
for num_units in hidden_units:
features = layers.Dense(num_units)(features)
features = layers.BatchNormalization()(features)
features = layers.LeakyReLU()(features)
features = layers.Dropout(dropout_rate)(features)
outputs = layers.Dense(units=1)(features)
model = keras.Model(inputs=inputs, outputs=outputs)
return model