mahout 推荐系统之 hello world

不念不忘少年蓝@ 2022-05-15 05:57 151阅读 0赞

**前言：**推荐系统的输入是必要的 ,这些数据是推荐的基础。因为非常熟悉的推荐系统引擎将item(物品)推荐给user(用户)，很容易的认为偏好(Preference)是user和item之间的联系。偏好包含了一个user ID和一个item ID，通常情况下，一个数值代表了user对item偏好的强度。Mahout中ID都是数值，实际上是整数（lang型）。偏好值可以是任何值，值越大代表这正向偏好 越大。例如，这些值可能是1到5的打分，user将1给于他不喜欢的，5给他很喜欢的。

基础数据：intro.csv

1,101,5.0
    1,102,3.0
    1,103,2.5
    
    2,101,2.0
    2,102,2.5
    2,103,5.0
    2,104,2.0
    
    3,101,2.5
    3,104,4.0
    3,105,4.5
    3,107,5.0
    
    4,101,5.0
    4,103,3.0
    4,104,4.5
    4,106,4.0
    
    5,101,4.0
    5,102,3.0
    5,103,2.0
    5,104,4.0
    5,105,3.5
    5,106,4.0

用户1和用户5具有相同的喜好。他们都喜欢101这本书，对102的喜欢弱一些，对103的喜欢更弱。同理，用户1和4具有相同的兴趣，他们都喜欢101和103，没有信息显示用户4喜欢102。另一方面，用户1和用户2的兴趣好像正好相反，用户1喜欢 101，但用户2讨厌101，用户1喜欢103而用户2正好相反。用户1和3的交集很少，只有101这本书显示了他们的兴趣。

简单的推荐程序demo，如下：

package com.xh.recommender;
    
    import org.apache.mahout.cf.taste.impl.model.file.FileDataModel;
    import org.apache.mahout.cf.taste.impl.neighborhood.NearestNUserNeighborhood;
    import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;
    import org.apache.mahout.cf.taste.impl.similarity.PearsonCorrelationSimilarity;
    import org.apache.mahout.cf.taste.model.DataModel;
    import org.apache.mahout.cf.taste.neighborhood.UserNeighborhood;
    import org.apache.mahout.cf.taste.recommender.RecommendedItem;
    import org.apache.mahout.cf.taste.recommender.Recommender;
    import org.apache.mahout.cf.taste.similarity.UserSimilarity;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    import java.io.File;
    import java.net.URL;
    import java.util.List;
    
    /** * @author xiaohe * @version V1.0.0 * @Description: mahout 推荐简介 * @date: 2018-8-20 20:51 * @Copyright: */
    public class RecommenderIntro {
    
        private static Logger logger = LoggerFactory.getLogger(RecommenderIntro.class);
    
        public static void main(String[] args) throws Exception {
            final String filePath = "recommend/intro.csv";
            URL url = RecommenderIntro.class.getClassLoader()
                    .getResource(filePath);
            File modelFile = new File(url.getFile());
            if(!modelFile.exists()) {
                System.err.println("Please, specify name of file, or put file 'input.csv' into current directory!");
                System.exit(1);
            }
            /** * * 装载 数据 文件 * DataModel 实现储存并为计算机提供所需的所有偏好、用户和物品数据 * */
            DataModel model = new FileDataModel(modelFile);
            /** * UserSimilarity 实现给出两个用户之间的相似度 * 可以从多种可能度量或计算机中选一种作为依赖 */
            UserSimilarity similarity = new PearsonCorrelationSimilarity(model);
    
            // UserNeighborhood 实现   明确与给定用户最相似的一组用户
            UserNeighborhood neighborhood =
                    new NearestNUserNeighborhood(2, similarity, model);
    
            /** * * 生成推荐引擎 * Recommender 合并所有的组件为用户推荐物品 * */
            Recommender recommender = new GenericUserBasedRecommender(
                    model, neighborhood, similarity);
            // 为用户1 推荐2件  物品
            List<RecommendedItem> recommendations =
                    recommender.recommend(1, 2);
    
            for (RecommendedItem recommendation : recommendations) {
                System.out.println(recommendation);
            }
    
        }
    
    }

项目结构如图：  
![这里写图片描述][70]

附上pom.xml

<?xml version="1.0" encoding="UTF-8"?>
    
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.xh</groupId>
        <artifactId>springboot-mahout</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <packaging>war</packaging>
    
        <name>springboot-mahout Maven Webapp</name>
        
        <url>http://www.example.com</url>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <maven.compiler.source>1.8</maven.compiler.source>
            <maven.compiler.target>1.8</maven.compiler.target>
        </properties>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.5.8.RELEASE</version>
            <relativePath /> 
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
    
            <dependency>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-annotations</artifactId>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-core</artifactId>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-databind</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.apache.mahout</groupId>
                <artifactId>mahout-core</artifactId>
                <version>0.9</version>
            </dependency>
    
            
            <dependency>
                <groupId>commons-io</groupId>
                <artifactId>commons-io</artifactId>
                <version>2.6</version>
            </dependency>
    
        </dependencies>
    
        <build>
            <finalName>springboot-mahout</finalName>
        </build>
    </project>

[70]: /images/20220515/1742ba86bc874a4cb1c7b6eef0198f76.png