# Copyright 2018 The Cornac Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ============================================================================
import numpy as np
from tqdm.auto import tqdm
from ..recommender import Recommender
from ..recommender import ANNMixin, MEASURE_DOT
from ...exception import CornacException
from ...utils import fast_dot
from ...utils import get_rng
from ...utils.init_utils import zeros, xavier_uniform
[docs]
class VBPR(Recommender, ANNMixin):
"""Visual Bayesian Personalized Ranking.
Parameters
----------
k: int, optional, default: 10
The dimension of the gamma latent factors.
k2: int, optional, default: 10
The dimension of the theta latent factors.
n_epochs: int, optional, default: 20
Maximum number of epochs for SGD.
batch_size: int, optional, default: 100
The batch size for SGD.
learning_rate: float, optional, default: 0.001
The learning rate for SGD.
lambda_w: float, optional, default: 0.01
The regularization hyper-parameter for latent factor weights.
lambda_b: float, optional, default: 0.01
The regularization hyper-parameter for biases.
lambda_e: float, optional, default: 0.0
The regularization hyper-parameter for embedding matrix E and beta prime vector.
use_gpu: boolean, optional, default: True
Whether or not to use GPU to speed up training.
trainable: boolean, optional, default: True
When False, the model is not trained and Cornac assumes that the model already \
pre-trained (U and V are not None).
verbose: boolean, optional, default: True
When True, running logs are displayed.
init_params: dictionary, optional, default: None
Initial parameters, e.g., init_params = {'Bi': beta_item, 'Gu': gamma_user,
'Gi': gamma_item, 'Tu': theta_user, 'E': emb_matrix, 'Bp': beta_prime}
seed: int, optional, default: None
Random seed for weight initialization.
References
----------
* He, R., & McAuley, J. (2016). VBPR: Visual Bayesian Personalized Ranking from Implicit Feedback.
"""
def __init__(
self,
name="VBPR",
k=10,
k2=10,
n_epochs=50,
batch_size=100,
learning_rate=0.005,
lambda_w=0.01,
lambda_b=0.01,
lambda_e=0.0,
use_gpu=False,
trainable=True,
verbose=True,
init_params=None,
seed=None,
):
super().__init__(name=name, trainable=trainable, verbose=verbose)
self.k = k
self.k2 = k2
self.n_epochs = n_epochs
self.batch_size = batch_size
self.learning_rate = learning_rate
self.lambda_w = lambda_w
self.lambda_b = lambda_b
self.lambda_e = lambda_e
self.use_gpu = use_gpu
self.seed = seed
# Init params if provided
self.init_params = {} if init_params is None else init_params
self.beta_item = self.init_params.get("Bi", None)
self.gamma_user = self.init_params.get("Gu", None)
self.gamma_item = self.init_params.get("Gi", None)
self.theta_user = self.init_params.get("Tu", None)
self.emb_matrix = self.init_params.get("E", None)
self.beta_prime = self.init_params.get("Bp", None)
def _init(self, n_users, n_items, features):
rng = get_rng(self.seed)
self.beta_item = zeros(n_items) if self.beta_item is None else self.beta_item
if self.gamma_user is None:
self.gamma_user = xavier_uniform((n_users, self.k), rng)
if self.gamma_item is None:
self.gamma_item = xavier_uniform((n_items, self.k), rng)
if self.theta_user is None:
self.theta_user = xavier_uniform((n_users, self.k2), rng)
if self.emb_matrix is None:
self.emb_matrix = xavier_uniform((features.shape[1], self.k2), rng)
if self.beta_prime is None:
self.beta_prime = xavier_uniform((features.shape[1], 1), rng)
# pre-computed for faster evaluation
self.theta_item = np.matmul(features, self.emb_matrix)
self.visual_bias = np.matmul(features, self.beta_prime).ravel()
[docs]
def fit(self, train_set, val_set=None):
"""Fit the model to observations.
Parameters
----------
train_set: :obj:`cornac.data.Dataset`, required
User-Item preference data as well as additional modalities.
val_set: :obj:`cornac.data.Dataset`, optional, default: None
User-Item preference data for model selection purposes (e.g., early stopping).
Returns
-------
self : object
"""
Recommender.fit(self, train_set, val_set)
if train_set.item_image is None:
raise CornacException("item_image modality is required but None.")
# Item visual feature from CNN
train_features = train_set.item_image.features[: self.total_items]
train_features = train_features.astype(np.float32)
self._init(
n_users=self.total_users,
n_items=self.total_items,
features=train_features,
)
if self.trainable:
self._fit_torch(train_set, train_features)
return self
def _fit_torch(self, train_set, train_features):
import torch
def _l2_loss(*tensors):
l2_loss = 0
for tensor in tensors:
l2_loss += tensor.pow(2).sum()
return l2_loss / 2
def _inner(a, b):
return (a * b).sum(dim=1)
dtype = torch.float
device = (
torch.device("cuda:0")
if (self.use_gpu and torch.cuda.is_available())
else torch.device("cpu")
)
F = torch.tensor(train_features, device=device, dtype=dtype)
# Learned parameters
Bi = torch.tensor(
self.beta_item, device=device, dtype=dtype, requires_grad=True
)
Gu = torch.tensor(
self.gamma_user, device=device, dtype=dtype, requires_grad=True
)
Gi = torch.tensor(
self.gamma_item, device=device, dtype=dtype, requires_grad=True
)
Tu = torch.tensor(
self.theta_user, device=device, dtype=dtype, requires_grad=True
)
E = torch.tensor(
self.emb_matrix, device=device, dtype=dtype, requires_grad=True
)
Bp = torch.tensor(
self.beta_prime, device=device, dtype=dtype, requires_grad=True
)
optimizer = torch.optim.Adam([Bi, Gu, Gi, Tu, E, Bp], lr=self.learning_rate)
for epoch in range(1, self.n_epochs + 1):
sum_loss = 0.0
count = 0
progress_bar = tqdm(
total=train_set.num_batches(self.batch_size),
desc="Epoch {}/{}".format(epoch, self.n_epochs),
disable=not self.verbose,
)
for batch_u, batch_i, batch_j in train_set.uij_iter(
self.batch_size, shuffle=True
):
gamma_u = Gu[batch_u]
theta_u = Tu[batch_u]
beta_i = Bi[batch_i]
beta_j = Bi[batch_j]
gamma_i = Gi[batch_i]
gamma_j = Gi[batch_j]
feat_i = F[batch_i]
feat_j = F[batch_j]
gamma_diff = gamma_i - gamma_j
feat_diff = feat_i - feat_j
Xuij = (
beta_i
- beta_j
+ _inner(gamma_u, gamma_diff)
+ _inner(theta_u, feat_diff.mm(E))
+ feat_diff.mm(Bp)
)
log_likelihood = torch.nn.functional.logsigmoid(Xuij).sum()
reg = (
_l2_loss(gamma_u, gamma_i, gamma_j, theta_u) * self.lambda_w
+ _l2_loss(beta_i) * self.lambda_b
+ _l2_loss(beta_j) * self.lambda_b / 10
+ _l2_loss(E, Bp) * self.lambda_e
)
loss = -log_likelihood + reg
optimizer.zero_grad()
loss.backward()
optimizer.step()
sum_loss += loss.data.item()
count += len(batch_u)
if count % (self.batch_size * 10) == 0:
progress_bar.set_postfix(loss=(sum_loss / count))
progress_bar.update(1)
progress_bar.close()
print("Optimization finished!")
self.beta_item = Bi.data.cpu().numpy()
self.gamma_user = Gu.data.cpu().numpy()
self.gamma_item = Gi.data.cpu().numpy()
self.theta_user = Tu.data.cpu().numpy()
self.emb_matrix = E.data.cpu().numpy()
self.beta_prime = Bp.data.cpu().numpy()
# pre-computed for faster evaluation
self.theta_item = F.mm(E).data.cpu().numpy()
self.visual_bias = F.mm(Bp).data.cpu().numpy().ravel()
[docs]
def score(self, user_idx, item_idx=None):
"""Predict the scores/ratings of a user for an item.
Parameters
----------
user_idx: int, required
The index of the user for whom to perform score prediction.
item_idx: int, optional, default: None
The index of the item for which to perform score prediction.
If None, scores for all known items will be returned.
Returns
-------
res : A scalar or a Numpy array
Relative scores that the user gives to the item or to all known items
"""
if item_idx is None:
known_item_scores = np.add(self.beta_item, self.visual_bias)
fast_dot(self.gamma_user[user_idx], self.gamma_item, known_item_scores)
fast_dot(self.theta_user[user_idx], self.theta_item, known_item_scores)
return known_item_scores
else:
item_score = np.add(self.beta_item[item_idx], self.visual_bias[item_idx])
item_score += np.dot(self.gamma_item[item_idx], self.gamma_user[user_idx])
item_score += np.dot(self.theta_item[item_idx], self.theta_user[user_idx])
return item_score
[docs]
def get_vector_measure(self):
"""Getting a valid choice of vector measurement in ANNMixin._measures.
Returns
-------
measure: MEASURE_DOT
Dot product aka. inner product
"""
return MEASURE_DOT
[docs]
def get_user_vectors(self):
"""Getting a matrix of user vectors serving as query for ANN search.
Returns
-------
out: numpy.array
Matrix of user vectors for all users available in the model.
"""
user_vectors = np.concatenate(
(
self.gamma_user,
self.theta_user,
np.ones([self.gamma_user.shape[0], 1]),
np.ones([self.gamma_user.shape[0], 1]),
),
axis=1,
)
return user_vectors
[docs]
def get_item_vectors(self):
"""Getting a matrix of item vectors used for building the index for ANN search.
Returns
-------
out: numpy.array
Matrix of item vectors for all items available in the model.
"""
item_vectors = np.concatenate(
(
self.gamma_item,
self.theta_item,
self.beta_item.reshape((-1, 1)),
self.visual_bias.reshape((-1, 1)),
),
axis=1,
)
return item_vectors
