Javaを使用してCMSシステムのレコメンドアルゴリズム機能を実装する方法

import java.util.HashMap;
import java.util.Map;

public class ContentBasedRecommendation {
    // 用户行为矩阵，key为用户ID，value为用户的历史行为记录
    private Map<String, Map<String, Integer>> userBehaviorMatrix;

    // 内容特征矩阵，key为内容ID，value为内容的特征向量
    private Map<String, Map<String, Double>> contentFeatureMatrix;

    public ContentBasedRecommendation() {
        userBehaviorMatrix = new HashMap<>();
        contentFeatureMatrix = new HashMap<>();
    }

    // 添加用户的历史行为记录
    public void addUserBehavior(String userId, Map<String, Integer> behavior) {
        userBehaviorMatrix.put(userId, behavior);
    }

    // 添加内容的特征向量
    public void addContentFeature(String contentId, Map<String, Double> feature) {
        contentFeatureMatrix.put(contentId, feature);
    }

    // 计算用户和内容之间的相似度
    public double computeSimilarity(String userId, String contentId) {
        Map<String, Integer> userBehavior = userBehaviorMatrix.get(userId);
        Map<String, Double> contentFeature = contentFeatureMatrix.get(contentId);

        double similarity = 0.0;
        double userBehaviorNorm = 0.0;
        double contentFeatureNorm = 0.0;

        for (Map.Entry<String, Integer> entry : userBehavior.entrySet()) {
            String feature = entry.getKey();
            int behavior = entry.getValue();

            userBehaviorNorm += behavior * behavior;

            if (contentFeature.containsKey(feature)) {
                double contentFeatureValue = contentFeature.get(feature);
                similarity += behavior * contentFeatureValue;
                contentFeatureNorm += contentFeatureValue * contentFeatureValue;
            }
        }

        userBehaviorNorm = Math.sqrt(userBehaviorNorm);
        contentFeatureNorm = Math.sqrt(contentFeatureNorm);

        if (userBehaviorNorm == 0.0 || contentFeatureNorm == 0.0) {
            return 0.0;
        }

        return similarity / (userBehaviorNorm * contentFeatureNorm);
    }

    // 为用户生成推荐结果
    public void generateRecommendation(String userId, int n) {
        Map<String, Double> contentSimilarities = new HashMap<>();

        for (Map.Entry<String, Map<String, Integer>> userEntry : userBehaviorMatrix.entrySet()) {
            String otherUserId = userEntry.getKey();

            if (otherUserId.equals(userId)) {
                continue;
            }

            double similaritySum = 0.0;

            for (Map.Entry<String, Integer> behaviorEntry : userEntry.getValue().entrySet()) {
                String contentId = behaviorEntry.getKey();
                int behavior = behaviorEntry.getValue();

                double similarity = computeSimilarity(userId, contentId);
                similaritySum += behavior * similarity;
            }

            contentSimilarities.put(otherUserId, similaritySum);
        }

        // 根据相似度排序，选取前N个最相似的内容
        contentSimilarities.entrySet().stream()
                .sorted(Map.Entry.comparingByValue())
                .limit(n)
                .forEach(entry -> System.out.println(entry.getKey()));
    }

    public static void main(String[] args) {
        ContentBasedRecommendation recommendation = new ContentBasedRecommendation();

        // 添加用户的历史行为记录
        Map<String, Integer> userBehavior1 = new HashMap<>();
        userBehavior1.put("content1", 1);
        userBehavior1.put("content2", 1);
        recommendation.addUserBehavior("user1", userBehavior1);

        Map<String, Integer> userBehavior2 = new HashMap<>();
        userBehavior2.put("content2", 1);
        userBehavior2.put("content3", 1);
        recommendation.addUserBehavior("user2", userBehavior2);

        // 添加内容的特征向量
        Map<String, Double> contentFeature1 = new HashMap<>();
        contentFeature1.put("feature1", 1.0);
        contentFeature1.put("feature2", 1.0);
        recommendation.addContentFeature("content1", contentFeature1);

        Map<String, Double> contentFeature2 = new HashMap<>();
        contentFeature2.put("feature2", 1.0);
        contentFeature2.put("feature3", 1.0);
        recommendation.addContentFeature("content2", contentFeature2);

        recommendation.generateRecommendation("user1", 1);
    }
}