一、基于用户的Jaccard相似度公式

其中，u、v表示任意两个用户，N(u)表示用户u喜欢的物品集合,N(v)表示用户v喜欢物品的集合。

代码

public class UserCFApp {public static void main(String[]args){SparkConf sparkConf = new SparkConf();sparkConf.setAppName("UserCFApp");sparkConf.setMaster("local[*]");SparkSession sparkSession = SparkSession.builder().config(sparkConf).getOrCreate();String url = "jdbc:mysql://localhost:3306/spark-mysql?useUnicode=true&characterEncoding=utf8&autoReconnect=true&failOverReadOnly=false";String driver = "com.mysql.jdbc.Driver";String user = "root";String password = "admin";Dataset<Row> dataset = sparkSession.read().format("jdbc").option("driver", driver).option("url",url).option("dbtable","user_item").option("user",user).option("password",password).load();Dataset<Row> userCount = dataset.groupBy("user_id").count();Dataset<Row> user2UserCount = dataset.as("a").join(dataset.as("b"),functions.column("a.item_id").$eq$eq$eq(functions.column("b.item_id"))).where(functions.column("a.user_id").notEqual(functions.column("b.user_id"))).select(functions.column("a.user_id").as("a_user_id"),functions.column("b.user_id").as("b_user_id")).groupBy("a_user_id", "b_user_id").count();Dataset<Row> result =  user2UserCount.as("u2u").join(userCount.as("uc1"), functions.column("u2u.a_user_id").$eq$eq$eq(functions.column("uc1.user_id"))).join(userCount.as("uc2"), functions.column("u2u.b_user_id").$eq$eq$eq(functions.column("uc2.user_id"))).selectExpr("u2u.a_user_id", "u2u.b_user_id", "u2u.count/(uc1.count + uc2.count - u2u.count) as count");result.show();
//        result.write()
//                .mode(SaveMode.Overwrite)
//                .format("jdbc")
//                .option("driver", driver)
//                .option("url",url)
//                .option("dbtable","user_similar")
//                .option("user",user)
//                .option("password",password)
//                .save();sparkSession.stop();}
}

 

二、基于用户的余弦相似度公式

其中，u、v表示任意两个用户，N(u)表示用户u喜欢的物品集合,N(v)表示用户v喜欢物品的集合。

public class UserCF2App {public static void main(String[]args){SparkConf sparkConf = new SparkConf();sparkConf.setAppName("UserCFApp");sparkConf.setMaster("local[*]");SparkSession sparkSession = SparkSession.builder().config(sparkConf).getOrCreate();String url = "jdbc:mysql://localhost:3306/spark-mysql?useUnicode=true&characterEncoding=utf8&autoReconnect=true&failOverReadOnly=false";String driver = "com.mysql.jdbc.Driver";String user = "root";String password = "admin";Dataset<Row> dataset = sparkSession.read().format("jdbc").option("driver", driver).option("url",url).option("dbtable","user_item").option("user",user).option("password",password).load();Dataset<Row> userCount = dataset.groupBy("user_id").count();Dataset<Row> user2UserCount = dataset.as("a").join(dataset.as("b"),functions.column("a.item_id").$eq$eq$eq(functions.column("b.item_id"))).where(functions.column("a.user_id").notEqual(functions.column("b.user_id"))).select(functions.column("a.user_id").as("a_user_id"),functions.column("b.user_id").as("b_user_id")).groupBy("a_user_id", "b_user_id").count();Dataset<Row> result =  user2UserCount.as("u2u").join(userCount.as("uc1"), functions.column("u2u.a_user_id").$eq$eq$eq(functions.column("uc1.user_id"))).join(userCount.as("uc2"), functions.column("u2u.b_user_id").$eq$eq$eq(functions.column("uc2.user_id"))).selectExpr("u2u.a_user_id", "u2u.b_user_id", "u2u.count/pow(uc1.count * uc2.count, 0.5) as count");result.show();
//        result.write()
//                .mode(SaveMode.Overwrite)
//                .format("jdbc")
//                .option("driver", driver)
//                .option("url",url)
//                .option("dbtable","user_similar")
//                .option("user",user)
//                .option("password",password)
//                .save();sparkSession.stop();}
}