基于movie lens-100k数据集的协同过滤算法实现

数据集处理
基于用户的协同过滤算法的实现
基于物品的协同过滤算法的实现

数据集处理

import pandas as pd

u_data = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.data')
u_genre = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.genre')
u_info = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.info')
# u_item = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.item')
u_occupation = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.occupation')
# u_user = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.user')
u_user = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.user', encoding='GBK', sep='|', names=['user_id', 'age', 'gender', 'occupation', 'zip_code'])

# 加载评分数据集
u_ratings = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u.data', sep='\t', names=['user_id', 'item_id', 'rating', 'timestamp'])

# 合并用户信息(u_user)和评分信息(u_ratings)
u_result = pd.merge(u_user, u_ratings, on='user_id')

# 保存结果到u_result.csv文件
u_result.to_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u_result_text1.csv', index=False)

u_result_sorted = u_result.sort_values(by='user_id')

# 保存结果到 u_result_sorted.csv 文件
u_result_sorted.to_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u_result_sorted.csv', index=False)

文件结构

基于用户的协同过滤算法的实现

import pandas as pd
from sklearn.metrics.pairwise import cosine_similarity

# 加载处理好的文件
u_result = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u_result_text1.csv')

# 构件用户-物品评分矩阵
ratings_matrix = u_result.pivot_table(index='user_id', columns='item_id', values='rating').fillna(0)
print("评分矩阵：", ratings_matrix)

# 计算用户之间的相似度
user_similarity = cosine_similarity(ratings_matrix)
print("用户之间的相似度矩阵：", user_similarity)
rows = user_similarity.shape[0]
columns = user_similarity.shape[1]
print("矩阵的行数为：", rows)
print("矩阵的列数为：", columns)
def generate_recommendations(ratings_matrix, user_similarity, user_id, k, min_rating_threshold):
    # 找到目标用户已经评分的物品
    rated_items = ratings_matrix.loc[user_id]

    # 找到与目标用户相似度最高的k个邻居用户
    similarities = list(enumerate(user_similarity[user_id]))
    similarities.sort(key=lambda x: x[1], reverse=True)
    neighbors = [x[0] for x in similarities[1:k + 1]]
    print("邻居用户：", neighbors)

    # 汇总邻居用户的评分记录
    neighbor_ratings = ratings_matrix.loc[neighbors]

    # 根据邻居用户的评分记录和预测评分公式生成推荐列表
    recommendations = []
    for item_id, rating in neighbor_ratings.items():
        if rated_items[item_id] == 0:  # 只考虑目标用户未评分过的物品
            prediction = predict_rating(neighbor_ratings, user_similarity, user_id, item_id, k)
            if prediction > min_rating_threshold:  # 添加阈值条件
                recommendations.append((item_id, prediction))
    # print("第一次打印：", recommendations)
    recommendations.sort(key=lambda x: x[1], reverse=True)  # 按照预测评分降序排序
    return recommendations
    # 预测评分公式
def predict_rating(ratings_matrix, user_similarity, user_id, item_id, k):
    numerator = 0  # 分子
    denominator = 0  # 分母

    # 找到与目标用户相似度最高的k个邻居用户
    similarities = list(enumerate(user_similarity[user_id]))
    similarities.sort(key=lambda x: x[1], reverse=True)
    neighbors = [x[0] for x in similarities[1:k + 1]]

    for neighbor in neighbors:
        similarity = user_similarity[user_id][neighbor]
        rating = ratings_matrix.loc[neighbor, item_id]
        numerator += similarity * rating
        denominator += similarity
    if denominator != 0:
        prediction = numerator / denominator
    else:
        prediction = 0
    return prediction

user_id = 98  # 目标用户ID
k = 3  # 邻居数量
min_rating_threshold = 4.0  # 最小预测评分阈值

recommendations = generate_recommendations(ratings_matrix, user_similarity, user_id, k, min_rating_threshold)
# print("预测物品列表：")
print(recommendations)

基于物品的协同过滤算法的实现

import pandas as pd
from sklearn.metrics.pairwise import cosine_similarity

# 加载处理好的文件
u_result = pd.read_csv('D:/PyCharmWorkSpace/ml-100k/ml-100k/u_result_text1.csv')
# 构件物品-用户评分矩阵
ratings_matrix = u_result.pivot_table(index='item_id', columns='user_id', values='rating').fillna(0)
print("评分矩阵：", ratings_matrix)
# 计算物品之间的相似度
item_similarity = cosine_similarity(ratings_matrix)
print("物品之间的相似度矩阵：", item_similarity)

def generate_recommendations(ratings_matrix, item_similarity, user_id, k, min_rating_threshold):
    # 找到目标用户已经评分的物品
    rated_items = ratings_matrix.transpose().loc[user_id]

    # 找到与目标物品相似度最高的k个邻居物品
    similarities = list(enumerate(item_similarity[user_id]))
    similarities.sort(key=lambda x: x[1], reverse=True)
    neighbors = [x[0] for x in similarities[1:k + 1]]
    print("邻居物品：", neighbors)
    # 根据邻居物品的评分记录和预测评分公式生成推荐列表
    recommendations = []
    for neighbor in neighbors:
        neighbor_ratings = ratings_matrix[neighbor]
        for user, rating in neighbor_ratings.items():
            if rated_items[user] == 0:  # 只考虑目标用户未评分过的物品
                prediction = predict_rating(ratings_matrix, item_similarity, user, neighbor, k)
                if prediction > min_rating_threshold:  # 添加阈值条件
                    recommendations.append((user, prediction))

    recommendations.sort(key=lambda x: x[1], reverse=True)  # 按照预测评分降序排序
    return recommendations

# 预测评分公式
def predict_rating(ratings_matrix, item_similarity, user_id, item_id, k):
    numerator = 0  # 分子
    denominator = 0  # 分母
    # 找到与目标物品相似度最高的k个邻居物品
    similarities = list(enumerate(item_similarity[item_id]))
    similarities.sort(key=lambda x: x[1], reverse=True)
    neighbors = [x[0] for x in similarities[1:k + 1]]
    for neighbor in neighbors:
        similarity = item_similarity[item_id][neighbor]
        rating = ratings_matrix[neighbor][user_id]
        numerator += similarity * rating
        denominator += similarity
    if denominator != 0:
        prediction = numerator / denominator
    else:
        prediction = 0
    return prediction
user_id = 98  # 目标用户ID
k = 3  # 邻居数量
min_rating_threshold = 3.3  # 最小预测评分阈值
recommendations = generate_recommendations(ratings_matrix, item_similarity, user_id, k, min_rating_threshold)
print(recommendations)