最近一直在研究《Mahout in Action》，今天才算是把第一部分看完。在Chapter 6中有一个例子，是实现协同过滤进行推荐的例子，不过书上的是针对布尔值的输入数据，在mahout的安装目录里面也有这个算法的详细源码，但是毕竟是源码，读起来有点晦涩，所以就参考了书上的例子编写了（书上的例子思路比较清楚）不仅仅是布尔值的输入数据的代码；
下面就详细说下思路及代码：
输入数据：
第一列代表用户名ID，后面是项目ID，用逗号分隔
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
第一个MR 就是把输入数据的每个用户的信息整合下：
如下：
userid:1,vector:{103:2.5,102:3.0,101:5.0}
userid:2,vector:{104:2.0,103:5.0,102:2.5,101:2.0}
userid:3,vector:{107:5.0,105:4.5,104:4.0,101:2.5}
userid:4,vector:{106:4.0,104:4.5,103:3.0,101:5.0}
userid:5,vector:{106:4.0,105:3.5,104:4.0,103:2.0,102:3.0,101:4.0}
全局变量的文件：
WiKiUtils.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
public class WiKiUtils {
public static final String PATH="hdfs://fansyonepc:9000/user/fansy/date1012/wikifirst/";
public static int RECOMMENDATIONSPERUSER=5;
public static String JOB1OUTPATH=PATH+"job1/part-r-00000"; // this is used in WiKi5Reducer' function setup to get the items that the user already give a value
}
WiKiDriver1.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import static org.fansy.date1012.mahoutinaction.chapter6.sourcecode.WiKiUtils.PATH;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.mahout.math.VarLongWritable;
import org.apache.mahout.math.VectorWritable;
public class WiKiDriver1 {
/**
* @param args
* @throws IOException
* @throws InterruptedException
* @throws ClassNotFoundException
*/
public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
// TODO Auto-generated method stub
Configuration conf1 = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf1, args).getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: WiKiDriver1 <in> <out>");
System.exit(2);
}
Job job1 = new Job(conf1, "wiki job one");
job1.setOutputFormatClass(SequenceFileOutputFormat.class);
job1.setNumReduceTasks(1);
job1.setJarByClass(WiKiDriver1.class);
job1.setMapperClass(WikiMapper1.class);
job1.setMapOutputKeyClass(VarLongWritable.class);
job1.setMapOutputValueClass(LongAndFloat.class);
job1.setReducerClass(WiKiReducer1.class);
job1.setOutputKeyClass(VarLongWritable.class);
job1.setOutputValueClass(VectorWritable.class);
FileInputFormat.addInputPath(job1, new Path("hdfs://fansyonepc:9000/user/fansy/input/"+otherArgs[0]));
SequenceFileOutputFormat.setOutputPath(job1, new Path(PATH+otherArgs[1]));
if(!job1.waitForCompletion(true)){
System.exit(1); // run error then exit
}
}
}
WiKiMapper1.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.IOException;
import org.apache.hadoop.io.FloatWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.math.VarLongWritable;
public class WikiMapper1 extends Mapper<LongWritable ,Text,VarLongWritable,LongAndFloat>{
// private static final Pattern NUMBERS=Pattern.compile("(\\d+)");
public void map(LongWritable key,Text value,Context context) throws IOException, InterruptedException{
VarLongWritable userID=new VarLongWritable();
LongWritable itemID=new LongWritable();
FloatWritable itemValue=new FloatWritable();
String line=value.toString();
String[] info=line.split(",");
if(info.length!=3){
return;
}
userID.set(Long.parseLong(info[0]));
itemID.set(Long.parseLong(info[1]));
itemValue.set(Float.parseFloat(info[2]));
context.write(userID, new LongAndFloat(itemID,itemValue));
}
}
WiKiReducer1.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.IOException;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.VarLongWritable;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
public class WiKiReducer1 extends Reducer<VarLongWritable,LongAndFloat,VarLongWritable,VectorWritable> {
public void reduce(VarLongWritable userID,Iterable<LongAndFloat> itemPrefs,Context context) throws IOException, InterruptedException{
// RandomAccessSparseVector(int cardinality, int initialCapacity)
Vector userVector=new RandomAccessSparseVector(Integer.MAX_VALUE,10);
for(LongAndFloat itemPref:itemPrefs){
userVector.set(Integer.parseInt(itemPref.getFirst().toString()),Float.parseFloat(itemPref.getSecond().toString()) );
}
context.write(userID, new VectorWritable(userVector));
// System.out.println("userid:"+userID+",vector:"+userVector);
}
}
LongAndFloat.java: 用于存储数据并实现Writable的数据类型
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.io.FloatWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.WritableComparable;
public class LongAndFloat implements WritableComparable<LongAndFloat> {
private LongWritable first;
private FloatWritable second;
public LongAndFloat(){
set(new LongWritable(),new FloatWritable());
}
public LongAndFloat(LongWritable l,FloatWritable f){
set(l,f);
}
public void set(LongWritable longWritable, FloatWritable intWritable) {
// TODO Auto-generated method stub
this.first=longWritable;
this.second=intWritable;
}
public LongWritable getFirst(){
return first;
}
public FloatWritable getSecond(){
return second;
}
@Override
public void readFields(DataInput arg0) throws IOException {
// TODO Auto-generated method stub
first.readFields(arg0);
second.readFields(arg0);
}
@Override
public void write(DataOutput arg0) throws IOException {
// TODO Auto-generated method stub
first.write(arg0);
second.write(arg0);
}
@Override
public int compareTo(LongAndFloat o) {
// TODO Auto-generated method stub
int cmp=first.compareTo(o.first);
if(cmp!=0){
return cmp;
}
return second.compareTo(o.second);
}
}
第二个MR：
输入数据为MR(1) 的输出 只是项目的相似度 先不管用户ID，直接对后面的所有项目进行拆分。
输出应该类似下面：
101,{107:1.0,106:2.0,105:2.0,104:4.0,103:4.0,102:3.0,101:5.0}
102,{106:1.0,105:1.0,104:2.0,103:3.0,102:3.0,101:3.0}
WiKiDriver2.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import static org.fansy.date1012.mahoutinaction.chapter6.sourcecode.WiKiUtils.*;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.mahout.math.VectorWritable;
public class WiKiDriver2 {
/**
* @param args
* @throws IOException
* @throws InterruptedException
* @throws ClassNotFoundException
*/
public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
// TODO Auto-generated method stub
Configuration conf1 = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf1, args).getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: WiKiDriver2 <in> <out>");
System.exit(2);
}
Job job1 = new Job(conf1, "wiki job two");
job1.setNumReduceTasks(1);
job1.setJarByClass(WiKiDriver2.class);
job1.setInputFormatClass(SequenceFileInputFormat.class);
job1.setMapperClass(WikiMapper2.class);
job1.setMapOutputKeyClass(IntWritable.class);
job1.setMapOutputValueClass(IntWritable.class);
job1.setReducerClass(WiKiReducer2.class);
job1.setOutputKeyClass(IntWritable.class);
job1.setOutputValueClass(VectorWritable.class);
job1.setOutputFormatClass(SequenceFileOutputFormat.class);
SequenceFileInputFormat.addInputPath(job1, new Path(PATH+otherArgs[0]));
SequenceFileOutputFormat.setOutputPath(job1, new Path(PATH+otherArgs[1]));
if(!job1.waitForCompletion(true)){
System.exit(1); // run error then exit
}
}
}
WiKiMapper2.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.math.VarLongWritable;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
public class WikiMapper2 extends Mapper<VarLongWritable ,VectorWritable,IntWritable,IntWritable>{
public void map(VarLongWritable userID,VectorWritable userVector,Context context) throws IOException, InterruptedException{
Iterator<Vector.Element> it=userVector.get().iterateNonZero();
while(it.hasNext()){
int index1=it.next().index();
// System.out.println("index1:"+index1);
Iterator<Vector.Element> it2=userVector.get().iterateNonZero();
while(it2.hasNext()){
int index2=it2.next().index();
// test
/*if(index1==101){
System.out.println("index1:"+index1+",index2:"+index2);
}*/
context.write(new IntWritable(index1), new IntWritable(index2));
}
}
}
}
WiKiReducer2.java
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.math.RandomAccessSparseVector;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
public class WiKiReducer2 extends Reducer<IntWritable,IntWritable,IntWritable,VectorWritable> {
public void reduce(IntWritable itemIndex1,Iterable<IntWritable> itemPrefs,Context context) throws IOException, InterruptedException{
// RandomAccessSparseVector(int cardinality, int initialCapacity)
Vector itemVector=new RandomAccessSparseVector(Integer.MAX_VALUE,10);
for(IntWritable itemPref:itemPrefs){
int itemIndex2=itemPref.get();
itemVector.set(itemIndex2, itemVector.get(itemIndex2)+1.0);
}
context.write(itemIndex1, new VectorWritable(itemVector));
// System.out.println(itemIndex1+","+itemVector);
}
}
第三个MR：
含有两个Mapper，第一个MR(31)把MR(2)的输出的格式转为VectorOrPrefWritable;
MR(32)针对MR(1)的输出把每一个项目ID和用户ID作为一对进行输出，输出格式也为VectorOrPrefWritable;
WiKiDriver31.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import static org.fansy.date1012.mahoutinaction.chapter6.sourcecode.WiKiUtils.PATH;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.mahout.cf.taste.hadoop.item.VectorOrPrefWritable;
public class WiKiDriver31 {
/**
* @param args
* @throws IOException
* @throws InterruptedException
* @throws ClassNotFoundException
*/
public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
// TODO Auto-generated method stub
Configuration conf1 = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf1, args).getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: WiKiDriver31 <in> <out>");
System.exit(2);
}
Job job1 = new Job(conf1, "wiki job three1");
job1.setOutputFormatClass(SequenceFileOutputFormat.class);
job1.setInputFormatClass(SequenceFileInputFormat.class);
job1.setNumReduceTasks(1);
job1.setJarByClass(WiKiDriver31.class);
job1.setMapperClass(WikiMapper31.class);
job1.setMapOutputKeyClass(IntWritable.class);
job1.setMapOutputValueClass(VectorOrPrefWritable.class);
// set a reducer only to use SequenceFileOutputFormat
job1.setReducerClass(WiKiReducer31.class);
job1.setOutputKeyClass(IntWritable.class);
job1.setOutputValueClass(VectorOrPrefWritable.class);
// this MR's input is the MR2's output
SequenceFileInputFormat.addInputPath(job1, new Path(PATH+otherArgs[0]));
SequenceFileOutputFormat.setOutputPath(job1, new Path(PATH+otherArgs[1]));
if(!job1.waitForCompletion(true)){
System.exit(1); // run error then exit
}
}
}
WiKiMapper31.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.cf.taste.hadoop.item.VectorOrPrefWritable;
import org.apache.mahout.math.VectorWritable;
public class WikiMapper31 extends Mapper<IntWritable ,VectorWritable,IntWritable,VectorOrPrefWritable>{
public void map(IntWritable key,VectorWritable value,Context context) throws IOException, InterruptedException{
context.write(key, new VectorOrPrefWritable(value.get()));
// System.out.println("key"+key.toString()+",vlaue"+value.get());
}
}
WiKiReducer31.java
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.mahout.cf.taste.hadoop.item.VectorOrPrefWritable;
public class WiKiReducer31 extends Reducer<IntWritable ,VectorOrPrefWritable,IntWritable,VectorOrPrefWritable> {
public void reduce(IntWritable key,Iterable<VectorOrPrefWritable> values ,Context context ) throws IOException, InterruptedException{
for(VectorOrPrefWritable va:values){
context.write(key, va);
}
}
}
WiKiDriver32.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import static org.fansy.date1012.mahoutinaction.chapter6.sourcecode.WiKiUtils.PATH;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.mahout.cf.taste.hadoop.item.VectorOrPrefWritable;
public class WiKiDriver32 {
/**
* @param args
* @throws IOException
* @throws InterruptedException
* @throws ClassNotFoundException
*/
public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
// TODO Auto-generated method stub
Configuration conf1 = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf1, args).getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: WiKiDriver32 <in> <out>");
System.exit(2);
}
Job job1 = new Job(conf1, "wiki job one");
job1.setOutputFormatClass(SequenceFileOutputFormat.class);
job1.setInputFormatClass(SequenceFileInputFormat.class);
job1.setNumReduceTasks(1);
job1.setJarByClass(WiKiDriver32.class);
job1.setMapperClass(WikiMapper32.class);
job1.setMapOutputKeyClass(IntWritable.class);
job1.setMapOutputValueClass(VectorOrPrefWritable.class);
job1.setReducerClass(WiKiReducer32.class);
job1.setOutputKeyClass(IntWritable.class);
job1.setOutputValueClass(VectorOrPrefWritable.class);
// the WiKiDriver's out put is this one's input
SequenceFileInputFormat.addInputPath(job1, new Path(PATH+otherArgs[0]));
SequenceFileOutputFormat.setOutputPath(job1, new Path(PATH+otherArgs[1]));
if(!job1.waitForCompletion(true)){
System.exit(1); // run error then exit
}
}
}
WikiMapper32.java:
package org.fansy.date1012.mahoutinaction.chapter6.sourcecode;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.cf.taste.hadoop.item.VectorOrPrefWritable;
import org.apache.mahout.math.VarLongWritable;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;
public class WikiMapper32 extends Mapper<VarLongWritable ,VectorWritable,IntWritable,VectorOrPrefWritable>{
public void map(VarLongWritable key,VectorWritable value,Context context) throws IOException, InterruptedException{
long userID=key.get();
Vector userVector=value.get();
Iterator<Vector.Element> it=userVector.iterateNonZero();
IntWritable itemi=new IntWritable();
while(it.hasNext()){
Vector.Element e=it.next();
int itemIndex=e.index();
float preferenceValue=(float)e.get();
itemi.set(itemIndex);
context.write(itemi, new VectorOrPrefWritable(userID,preferenceValue));
// System.out.println("item :"+itemi+",userand val:"+userID+","+preferenceValue);
}
// System.out.println();
}
}
WiKiReducer32.java 其实和WiKiReducer31.java一模一样的，此处不再给出；
下接 Hadoop 实现协同过滤 (example in <Mahout in action> chapter 6) Part 2
分享，快乐，成长