推荐模型BPR数据构建（含构建正负样本对）

参考链接：
https://www.cnblogs.com/leimu/p/13949945.html

1.读数据

import numpy as np 
import pandas as pd 
import scipy.sparse as sp
import torch.utils.data as data
import torch
import torch.nn as nn
import os
import time
dataset = 'ml-1m'
main_