生成矩阵

import numpyas np

import pandasas pd

#1、读入数据集

header = ["user_id","item_id","rating","timestamp"]

data =pd.read_csv("u.data",sep="\t",names=header)

#2、生成用户—物品评分矩阵

#检查是否有重复的用户物品打分记录

data.duplicated(subset = ["user_id","item_id"]).sum()

item_id_user = data.groupby("item_id").count()["user_id"]

#构建用户物品矩阵

users_num = data.user_id.max()

items_num = data.item_id.max()

user_item_rating = np.zeros((users_num,items_num))

for linein data.itertuples():#以元组的方式赋值

    user_item_rating[line[1]-1,line[2]-1] = line[3]

np.savetxt("评分12.csv", user_item_rating,delimiter =",")