数据挖掘--协同过滤算法，基于集合交集相似性计算的mapreduce算法设计

来源：互联网发布：简述单片机的控制原理编辑：程序博客网时间：2024/05/16 16:56

第一个过程程的mapreduce函数：

import java.io.File;import java.io.IOException;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import java.util.StringTokenizer;public class MapReduce extends MapperReduce{public MapReduce(){super();}public void printf(List<String> list1,List<String> list2) throws IOException{if((!list1.isEmpty()) && (!list2.isEmpty())){Iterator<String> Iter1=list1.iterator();while(Iter1.hasNext()){String tmp1=Iter1.next();Iterator<String> Iter2=list2.iterator();while(Iter2.hasNext()){String tmp2=Iter2.next();WriteReducer(tmp1,tmp2);}}}}//map函数开始public void Mapper(String key,String value) throws IOException{//key为行偏移量，value为每一行的值String[] count=value.split(" ");if(!count[1].trim().equals("")){WriteMaper(count[1].trim(),count[0].trim()+" "+"1");WriteMaper(count[1].trim(),count[0].trim()+" "+"2");}}//map函数结束//reduce函数开始public void Reducer(String key,Iterator<String> value) throws IOException{List<String> list1=new ArrayList<String>();List<String> list2=new ArrayList<String>();while(value.hasNext()){String tmp=value.next();String[] tmp1=tmp.split(" ");if(tmp1[1].equals("1")){list1.add(tmp1[0]);}else{list2.add(tmp1[0]);}}printf(list1,list2);}//reduce函数结束public static void main(String[] args) throws IOException {MapReduce a=new MapReduce();a.IterMapper();a.IterReducer();}}

本程序实例是：单表自连接，连接字段是 user

输入：

star1 user1
star2 user1
star3 user1
star3 user2

输出：

star1 star1
star1 star2
star1 star3
star2 star1
star2 star2
star2 star3
star3 star1
star3 star2
star3 star3
star3 star3

第二个过程程的mapreduce函数：

import java.io.IOException;import java.util.ArrayList;import java.util.HashMap;import java.util.HashSet;import java.util.Iterator;import java.util.List;import java.util.Map;import java.util.Set;public class MapReduce extends MapperReduce{public MapReduce(){super();}//map函数开始public void Mapper(String key,String value) throws IOException{String[] content=value.split(" ");WriteMaper(content[0],content[1]);}//map函数结束//reduce函数开始public void Reducer(String key,Iterator<String> value) throws IOException{List<String> list=new ArrayList<String>();while(value.hasNext()){list.add(value.next());}Set<String> set = new HashSet<String>(list);Map<String,Integer> map=new HashMap<String,Integer>();Iterator<String> IterSet=set.iterator();while(IterSet.hasNext()){map.put(IterSet.next(),0);}for(int i=0;i<list.size();i++){map.put(list.get(i),map.get(list.get(i))+1);}Iterator<String> It = map.keySet().iterator();while(It.hasNext()){   String tmp=It.next();if(!tmp.equals(key)){WriteReducer(key,tmp+" "+String.valueOf(((float)map.get(tmp))/map.get(key)));}    }}//reduce函数结束public static void main(String[] args) throws IOException {MapReduce a=new MapReduce();a.IterMapper();a.IterReducer();}}

输入：

star1 star1
star1 star2
star1 star3
star2 star1
star2 star2
star2 star3
star3 star1
star3 star2
star3 star3
star3 star3

输出：

star1 star2 1.0

star1 star3 1.0

star2 star1 1.0

star2 star3 1.0

star3 star1 0.5

star3 star2 0.5

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