# Copyright (c) Recommenders contributors.
# Licensed under the MIT License.
import os
import numpy as np
import tensorflow as tf
import tf_slim as slim
from time import time
import logging
tf.compat.v1.disable_eager_execution()
logger = logging.getLogger(__name__)
MODEL_CHECKPOINT = "model.ckpt"
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class NCF:
"""Neural Collaborative Filtering (NCF) implementation
:Citation:
He, Xiangnan, Lizi Liao, Hanwang Zhang, Liqiang Nie, Xia Hu, and Tat-Seng Chua. "Neural collaborative filtering."
In Proceedings of the 26th International Conference on World Wide Web, pp. 173-182. International World Wide Web
Conferences Steering Committee, 2017. Link: https://www.comp.nus.edu.sg/~xiangnan/papers/ncf.pdf
"""
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def __init__(
self,
n_users,
n_items,
model_type="NeuMF",
n_factors=8,
layer_sizes=[16, 8, 4],
n_epochs=50,
batch_size=64,
learning_rate=5e-3,
verbose=1,
seed=None,
):
"""Constructor
Args:
n_users (int): Number of users in the dataset.
n_items (int): Number of items in the dataset.
model_type (str): Model type.
n_factors (int): Dimension of latent space.
layer_sizes (list): Number of layers for MLP.
n_epochs (int): Number of epochs for training.
batch_size (int): Batch size.
learning_rate (float): Learning rate.
verbose (int): Whether to show the training output or not.
seed (int): Seed.
"""
# seed
tf.compat.v1.set_random_seed(seed)
np.random.seed(seed)
self.seed = seed
self.n_users = n_users
self.n_items = n_items
self.model_type = model_type.lower()
self.n_factors = n_factors
self.layer_sizes = layer_sizes
self.n_epochs = n_epochs
self.verbose = verbose
self.batch_size = batch_size
self.learning_rate = learning_rate
# check model type
model_options = ["gmf", "mlp", "neumf"]
if self.model_type not in model_options:
raise ValueError(
"Wrong model type, please select one of this list: {}".format(
model_options
)
)
# ncf layer input size
self.ncf_layer_size = n_factors + layer_sizes[-1]
# create ncf model
self._create_model()
# set GPU use with demand growth
gpu_options = tf.compat.v1.GPUOptions(allow_growth=True)
# set TF Session
self.sess = tf.compat.v1.Session(
config=tf.compat.v1.ConfigProto(gpu_options=gpu_options)
)
# parameters initialization
self.sess.run(tf.compat.v1.global_variables_initializer())
def _create_model(
self,
):
# reset graph
tf.compat.v1.reset_default_graph()
with tf.compat.v1.variable_scope("input_data", reuse=tf.compat.v1.AUTO_REUSE):
# input: index of users, items and ground truth
self.user_input = tf.compat.v1.placeholder(tf.int32, shape=[None, 1])
self.item_input = tf.compat.v1.placeholder(tf.int32, shape=[None, 1])
self.labels = tf.compat.v1.placeholder(tf.float32, shape=[None, 1])
with tf.compat.v1.variable_scope("embedding", reuse=tf.compat.v1.AUTO_REUSE):
# set embedding table
self.embedding_gmf_P = tf.Variable(
tf.random.truncated_normal(
shape=[self.n_users, self.n_factors],
mean=0.0,
stddev=0.01,
seed=self.seed,
),
name="embedding_gmf_P",
dtype=tf.float32,
)
self.embedding_gmf_Q = tf.Variable(
tf.random.truncated_normal(
shape=[self.n_items, self.n_factors],
mean=0.0,
stddev=0.01,
seed=self.seed,
),
name="embedding_gmf_Q",
dtype=tf.float32,
)
# set embedding table
self.embedding_mlp_P = tf.Variable(
tf.random.truncated_normal(
shape=[self.n_users, int(self.layer_sizes[0] / 2)],
mean=0.0,
stddev=0.01,
seed=self.seed,
),
name="embedding_mlp_P",
dtype=tf.float32,
)
self.embedding_mlp_Q = tf.Variable(
tf.random.truncated_normal(
shape=[self.n_items, int(self.layer_sizes[0] / 2)],
mean=0.0,
stddev=0.01,
seed=self.seed,
),
name="embedding_mlp_Q",
dtype=tf.float32,
)
with tf.compat.v1.variable_scope("gmf", reuse=tf.compat.v1.AUTO_REUSE):
# get user embedding p and item embedding q
self.gmf_p = tf.reduce_sum(
input_tensor=tf.nn.embedding_lookup(
params=self.embedding_gmf_P, ids=self.user_input
),
axis=1,
)
self.gmf_q = tf.reduce_sum(
input_tensor=tf.nn.embedding_lookup(
params=self.embedding_gmf_Q, ids=self.item_input
),
axis=1,
)
# get gmf vector
self.gmf_vector = self.gmf_p * self.gmf_q
with tf.compat.v1.variable_scope("mlp", reuse=tf.compat.v1.AUTO_REUSE):
# get user embedding p and item embedding q
self.mlp_p = tf.reduce_sum(
input_tensor=tf.nn.embedding_lookup(
params=self.embedding_mlp_P, ids=self.user_input
),
axis=1,
)
self.mlp_q = tf.reduce_sum(
input_tensor=tf.nn.embedding_lookup(
params=self.embedding_mlp_Q, ids=self.item_input
),
axis=1,
)
# concatenate user and item vector
output = tf.concat([self.mlp_p, self.mlp_q], 1)
# MLP Layers
for layer_size in self.layer_sizes[1:]:
output = slim.layers.fully_connected(
output,
num_outputs=layer_size,
activation_fn=tf.nn.relu,
weights_initializer=tf.compat.v1.keras.initializers.VarianceScaling(
scale=1.0,
mode="fan_avg",
distribution="uniform",
seed=self.seed,
),
)
self.mlp_vector = output
# self.output = tf.sigmoid(tf.reduce_sum(self.mlp_vector, axis=1, keepdims=True))
with tf.compat.v1.variable_scope("ncf", reuse=tf.compat.v1.AUTO_REUSE):
if self.model_type == "gmf":
# GMF only
output = slim.layers.fully_connected(
self.gmf_vector,
num_outputs=1,
activation_fn=None,
biases_initializer=None,
weights_initializer=tf.compat.v1.keras.initializers.VarianceScaling(
scale=1.0,
mode="fan_avg",
distribution="uniform",
seed=self.seed,
),
)
self.output = tf.sigmoid(output)
elif self.model_type == "mlp":
# MLP only
output = slim.layers.fully_connected(
self.mlp_vector,
num_outputs=1,
activation_fn=None,
biases_initializer=None,
weights_initializer=tf.compat.v1.keras.initializers.VarianceScaling(
scale=1.0,
mode="fan_avg",
distribution="uniform",
seed=self.seed,
),
)
self.output = tf.sigmoid(output)
elif self.model_type == "neumf":
# concatenate GMF and MLP vector
self.ncf_vector = tf.concat([self.gmf_vector, self.mlp_vector], 1)
# get predicted rating score
output = slim.layers.fully_connected(
self.ncf_vector,
num_outputs=1,
activation_fn=None,
biases_initializer=None,
weights_initializer=tf.compat.v1.keras.initializers.VarianceScaling(
scale=1.0,
mode="fan_avg",
distribution="uniform",
seed=self.seed,
),
)
self.output = tf.sigmoid(output)
with tf.compat.v1.variable_scope("loss", reuse=tf.compat.v1.AUTO_REUSE):
# set loss function
self.loss = tf.compat.v1.losses.log_loss(self.labels, self.output)
with tf.compat.v1.variable_scope("optimizer", reuse=tf.compat.v1.AUTO_REUSE):
# set optimizer
self.optimizer = tf.compat.v1.train.AdamOptimizer(
learning_rate=self.learning_rate
).minimize(self.loss)
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def save(self, dir_name):
"""Save model parameters in `dir_name`
Args:
dir_name (str): directory name, which should be a folder name instead of file name
we will create a new directory if not existing.
"""
# save trained model
if not os.path.exists(dir_name):
os.makedirs(dir_name)
saver = tf.compat.v1.train.Saver()
saver.save(self.sess, os.path.join(dir_name, MODEL_CHECKPOINT))
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def load(self, gmf_dir=None, mlp_dir=None, neumf_dir=None, alpha=0.5):
"""Load model parameters for further use.
GMF model --> load parameters in `gmf_dir`
MLP model --> load parameters in `mlp_dir`
NeuMF model --> load parameters in `neumf_dir` or in `gmf_dir` and `mlp_dir`
Args:
gmf_dir (str): Directory name for GMF model.
mlp_dir (str): Directory name for MLP model.
neumf_dir (str): Directory name for neumf model.
alpha (float): the concatenation hyper-parameter for gmf and mlp output layer.
Returns:
object: Load parameters in this model.
"""
# load pre-trained model
if self.model_type == "gmf" and gmf_dir is not None:
saver = tf.compat.v1.train.Saver()
saver.restore(self.sess, os.path.join(gmf_dir, MODEL_CHECKPOINT))
elif self.model_type == "mlp" and mlp_dir is not None:
saver = tf.compat.v1.train.Saver()
saver.restore(self.sess, os.path.join(mlp_dir, MODEL_CHECKPOINT))
elif self.model_type == "neumf" and neumf_dir is not None:
saver = tf.compat.v1.train.Saver()
saver.restore(self.sess, os.path.join(neumf_dir, MODEL_CHECKPOINT))
elif self.model_type == "neumf" and gmf_dir is not None and mlp_dir is not None:
# load neumf using gmf and mlp
self._load_neumf(gmf_dir, mlp_dir, alpha)
else:
raise NotImplementedError
def _load_neumf(self, gmf_dir, mlp_dir, alpha):
"""Load gmf and mlp model parameters for further use in NeuMF.
NeuMF model --> load parameters in `gmf_dir` and `mlp_dir`
"""
# load gmf part
variables = tf.compat.v1.global_variables()
# get variables with 'gmf'
var_flow_restore = [
val for val in variables if "gmf" in val.name and "ncf" not in val.name
]
# load 'gmf' variable
saver = tf.compat.v1.train.Saver(var_flow_restore)
# restore
saver.restore(self.sess, os.path.join(gmf_dir, MODEL_CHECKPOINT))
# load mlp part
variables = tf.compat.v1.global_variables()
# get variables with 'gmf'
var_flow_restore = [
val for val in variables if "mlp" in val.name and "ncf" not in val.name
]
# load 'gmf' variable
saver = tf.compat.v1.train.Saver(var_flow_restore)
# restore
saver.restore(self.sess, os.path.join(mlp_dir, MODEL_CHECKPOINT))
# concat pretrain h_from_gmf and h_from_mlp
vars_list = tf.compat.v1.get_collection(
tf.compat.v1.GraphKeys.GLOBAL_VARIABLES, scope="ncf"
)
assert len(vars_list) == 1
ncf_fc = vars_list[0]
# get weight from gmf and mlp
gmf_fc = tf.train.load_variable(gmf_dir, ncf_fc.name)
mlp_fc = tf.train.load_variable(mlp_dir, ncf_fc.name)
# load fc layer by tf.concat
assign_op = tf.compat.v1.assign(
ncf_fc, tf.concat([alpha * gmf_fc, (1 - alpha) * mlp_fc], axis=0)
)
self.sess.run(assign_op)
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def fit(self, data):
"""Fit model with training data
Args:
data (NCFDataset): initilized Dataset in ./dataset.py
"""
# get user and item mapping dict
self.user2id = data.user2id
self.item2id = data.item2id
self.id2user = data.id2user
self.id2item = data.id2item
# loop for n_epochs
for epoch_count in range(1, self.n_epochs + 1):
# negative sampling for training
train_begin = time()
# initialize
train_loss = []
# calculate loss and update NCF parameters
for user_input, item_input, labels in data.train_loader(self.batch_size):
user_input = np.array([self.user2id[x] for x in user_input])
item_input = np.array([self.item2id[x] for x in item_input])
labels = np.array(labels)
feed_dict = {
self.user_input: user_input[..., None],
self.item_input: item_input[..., None],
self.labels: labels[..., None],
}
# get loss and execute optimization
loss, _ = self.sess.run([self.loss, self.optimizer], feed_dict)
train_loss.append(loss)
train_time = time() - train_begin
# output every self.verbose
if self.verbose and epoch_count % self.verbose == 0:
logger.info(
"Epoch %d [%.2fs]: train_loss = %.6f "
% (epoch_count, train_time, sum(train_loss) / len(train_loss))
)
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def predict(self, user_input, item_input, is_list=False):
"""Predict function of this trained model
Args:
user_input (list or element of list): userID or userID list
item_input (list or element of list): itemID or itemID list
is_list (bool): if true, the input is list type
noting that list-wise type prediction is faster than element-wise's.
Returns:
list or float: A list of predicted rating or predicted rating score.
"""
if is_list:
output = self._predict(user_input, item_input)
return list(output.reshape(-1))
else:
output = self._predict(np.array([user_input]), np.array([item_input]))
return float(output.reshape(-1)[0])
def _predict(self, user_input, item_input):
# index converting
user_input = np.array([self.user2id[x] for x in user_input])
item_input = np.array([self.item2id[x] for x in item_input])
# get feed dict
feed_dict = {
self.user_input: user_input[..., None],
self.item_input: item_input[..., None],
}
# calculate predicted score
return self.sess.run(self.output, feed_dict)
