基于矩阵分解的CF算法实现

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作者
猴君
阅读量:5

矩阵分解(Matrix Factorization)是一种常用的协同过滤(Collaborative Filtering, CF)算法,常用于推荐系统中。下面是一个基于矩阵分解的CF算法的实现示例:

import numpy as np  class MatrixFactorizationCF:     def __init__(self, num_users, num_items, num_factors=10, learning_rate=0.01, reg_param=0.01, num_iterations=100):         self.num_users = num_users         self.num_items = num_items         self.num_factors = num_factors         self.learning_rate = learning_rate         self.reg_param = reg_param         self.num_iterations = num_iterations         self.user_factors = None         self.item_factors = None          def fit(self, train_data):         # 初始化用户和物品的隐因子矩阵         self.user_factors = np.random.normal(scale=1./self.num_factors, size=(self.num_users, self.num_factors))         self.item_factors = np.random.normal(scale=1./self.num_factors, size=(self.num_items, self.num_factors))                  for iteration in range(self.num_iterations):             for user_id, item_id, rating in train_data:                 error = rating - self.predict(user_id, item_id)                                  # 更新用户和物品的隐因子矩阵                 self.user_factors[user_id] += self.learning_rate * (error * self.item_factors[item_id] - self.reg_param * self.user_factors[user_id])                 self.item_factors[item_id] += self.learning_rate * (error * self.user_factors[user_id] - self.reg_param * self.item_factors[item_id])          def predict(self, user_id, item_id):         return np.dot(self.user_factors[user_id], self.item_factors[item_id]) 

使用示例:

# 创建一个矩阵分解的CF模型 cf_model = MatrixFactorizationCF(num_users=100, num_items=50, num_factors=10, learning_rate=0.01, reg_param=0.01, num_iterations=100)  # 使用训练数据训练模型 train_data = [(0, 0, 5), (1, 1, 3), (2, 2, 4), ...] cf_model.fit(train_data)  # 预测用户0对物品1的评分 user_id = 0 item_id = 1 predicted_rating = cf_model.predict(user_id, item_id) print("Predicted rating for user", user_id, "and item", item_id, ":", predicted_rating) 

以上示例演示了如何使用基于矩阵分解的CF算法对用户对物品的评分进行预测。在fit方法中,通过迭代优化用户和物品的隐因子矩阵,来逼近真实的评分数据。然后使用predict方法来预测用户对物品的评分。

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