计算结果：
~ hadoop fs -cat /user/hdfs/recommend/step1/part-00000
1
102:3.0,103:2.5,101:5.0
2
101:2.0,102:2.5,103:5.0,104:2.0
3
107:5.0,101:2.0,104:4.0,105:4.5
4
101:5.0,103:3.0,104:4.5,106:4.0
5
101:4.0,102:3.0,103:2.0,104:4.0,105:3.5,106:4.0
3). Step2.java，对物品组合列表进行计数，建立物品的同现矩阵
源代码：
package org.conan.myhadoop.recommend;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.RunningJob;
import org.apache.hadoop.mapred.TextInputFormat;
import org.apache.hadoop.mapred.TextOutputFormat;
import org.conan.myhadoop.hdfs.HdfsDAO;
public class Step2 {
public static class Step2_UserVectorToCooccurrenceMapper extends MapReduceBase implements Mapper<LongWritable, Text, Text, IntWritable> {
private final static Text k = new Text();
private final static IntWritable v = new IntWritable(1);
@Override
public void map(LongWritable key, Text values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
String[] tokens = Recommend.DELIMITER.split(values.toString());
for (int i = 1; i < tokens.length; i++) {
String itemID = tokens[i].split(":")[0];
for (int j = 1; j < tokens.length; j++) {
String itemID2 = tokens[j].split(":")[0];
k.set(itemID + ":" + itemID2);
output.collect(k, v);
}
}
}
}
public static class Step2_UserVectorToConoccurrenceReducer extends MapReduceBase implements Reducer<Text, IntWritable, Text, IntWritable> {
private IntWritable result = new IntWritable();
@Override
public void reduce(Text key, Iterator values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
int sum = 0;
while (values.hasNext()) {
sum += values.next().get();
}
result.set(sum);
output.collect(key, result);
}
}
public static void run(Map<String, String> path) throws IOException {
JobConf conf = Recommend.config();
String input = path.get("Step2Input");
String output = path.get("Step2Output");
HdfsDAO hdfs = new HdfsDAO(Recommend.HDFS, conf);
hdfs.rmr(output);
conf.setOutputKeyClass(Text.class);
conf.setOutputValueClass(IntWritable.class);
conf.setMapperClass(Step2_UserVectorToCooccurrenceMapper.class);
conf.setCombinerClass(Step2_UserVectorToConoccurrenceReducer.class);
conf.setReducerClass(Step2_UserVectorToConoccurrenceReducer.class);
conf.setInputFormat(TextInputFormat.class);
conf.setOutputFormat(TextOutputFormat.class);
FileInputFormat.setInputPaths(conf, new Path(input));
FileOutputFormat.setOutputPath(conf, new Path(output));
RunningJob job = JobClient.runJob(conf);
while (!job.isComplete()) {
job.waitForCompletion();
}
}
}
