# -*- coding: utf-8 -*-
# @Time : 2020/12/12
# @Author : Xingyu Pan
# @Email : panxy@ruc.edu.cn
r"""
CDAE
################################################
Reference:
Yao Wu et al., Collaborative denoising auto-encoders for top-n recommender systems. In WSDM 2016.
Reference code:
https://github.com/jasonyaw/CDAE
"""
import torch
import torch.nn as nn
from recbole.model.abstract_recommender import GeneralRecommender
from recbole.model.init import xavier_normal_initialization
from recbole.utils import InputType
[docs]class CDAE(GeneralRecommender):
r"""Collaborative Denoising Auto-Encoder (CDAE) is a recommendation model
for top-N recommendation that utilizes the idea of Denoising Auto-Encoders.
We implement the the CDAE model with only user dataloader.
"""
input_type = InputType.POINTWISE
def __init__(self, config, dataset):
super(CDAE, self).__init__(config, dataset)
self.reg_weight_1 = config["reg_weight_1"]
self.reg_weight_2 = config["reg_weight_2"]
self.loss_type = config["loss_type"]
self.hid_activation = config["hid_activation"]
self.out_activation = config["out_activation"]
self.embedding_size = config["embedding_size"]
self.corruption_ratio = config["corruption_ratio"]
self.history_item_id, self.history_item_value, _ = dataset.history_item_matrix()
self.history_item_id = self.history_item_id.to(self.device)
self.history_item_value = self.history_item_value.to(self.device)
if self.hid_activation == "sigmoid":
self.h_act = nn.Sigmoid()
elif self.hid_activation == "relu":
self.h_act = nn.ReLU()
elif self.hid_activation == "tanh":
self.h_act = nn.Tanh()
else:
raise ValueError("Invalid hidden layer activation function")
if self.out_activation == "sigmoid":
self.o_act = nn.Sigmoid()
elif self.out_activation == "relu":
self.o_act = nn.ReLU()
else:
raise ValueError("Invalid output layer activation function")
self.dropout = nn.Dropout(p=self.corruption_ratio)
self.h_user = nn.Embedding(self.n_users, self.embedding_size)
self.h_item = nn.Linear(self.n_items, self.embedding_size)
self.out_layer = nn.Linear(self.embedding_size, self.n_items)
# parameters initialization
self.apply(xavier_normal_initialization)
[docs] def forward(self, x_items, x_users):
h_i = self.dropout(x_items)
h_i = self.h_item(h_i)
h_u = self.h_user(x_users)
h = torch.add(h_u, h_i)
h = self.h_act(h)
out = self.out_layer(h)
return out
[docs] def get_rating_matrix(self, user):
r"""Get a batch of user's feature with the user's id and history interaction matrix.
Args:
user (torch.LongTensor): The input tensor that contains user's id, shape: [batch_size, ]
Returns:
torch.FloatTensor: The user's feature of a batch of user, shape: [batch_size, n_items]
"""
# Following lines construct tensor of shape [B,n_items] using the tensor of shape [B,H]
col_indices = self.history_item_id[user].flatten()
row_indices = (
torch.arange(user.shape[0])
.to(self.device)
.repeat_interleave(self.history_item_id.shape[1], dim=0)
)
rating_matrix = (
torch.zeros(1).to(self.device).repeat(user.shape[0], self.n_items)
)
rating_matrix.index_put_(
(row_indices, col_indices), self.history_item_value[user].flatten()
)
return rating_matrix
[docs] def calculate_loss(self, interaction):
x_users = interaction[self.USER_ID]
x_items = self.get_rating_matrix(x_users)
predict = self.forward(x_items, x_users)
if self.loss_type == "MSE":
predict = self.o_act(predict)
loss_func = nn.MSELoss(reduction="sum")
elif self.loss_type == "BCE":
loss_func = nn.BCEWithLogitsLoss(reduction="sum")
else:
raise ValueError("Invalid loss_type, loss_type must in [MSE, BCE]")
loss = loss_func(predict, x_items)
# l1-regularization
loss += self.reg_weight_1 * (
self.h_user.weight.norm(p=1) + self.h_item.weight.norm(p=1)
)
# l2-regularization
loss += self.reg_weight_2 * (
self.h_user.weight.norm() + self.h_item.weight.norm()
)
return loss
[docs] def predict(self, interaction):
users = interaction[self.USER_ID]
predict_items = interaction[self.ITEM_ID]
items = self.get_rating_matrix(users)
scores = self.forward(items, users)
scores = self.o_act(scores)
return scores[[torch.arange(len(predict_items)).to(self.device), predict_items]]
[docs] def full_sort_predict(self, interaction):
users = interaction[self.USER_ID]
items = self.get_rating_matrix(users)
predict = self.forward(items, users)
predict = self.o_act(predict)
return predict.view(-1)