需求如下：
有如图所示的输入文件。其中第一列代表ip地址，之后的偶数列代表搜索词，数字(奇数列)代表搜索次数，使用"\t"分隔。现在需要对搜索词进行分词并统计词频，此处不考虑搜索次数，可能是翻页，亦不考虑搜索链接的行为。
这里中文分词使用了IK分词包，直接将源码放入src中。感谢IK分词。
程序如下:
<span style="font-size:14px;">package seg;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FileSystem;
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.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.wltea.analyzer.core.IKSegmenter;
import org.wltea.analyzer.core.Lexeme;
/**
* @author zhf
* @version 创建时间：2014年8月16日 下午3:04:40
*/
public class SegmentTool extends Configured implements Tool{
public static void main(String[] args) throws Exception {
int exitCode = ToolRunner.run(new SegmentTool(), args);
System.exit(exitCode);
}
@Override
public int run(String[] arg0) throws Exception {
Configuration conf = new Configuration();
String[] args = new GenericOptionsParser(conf,arg0).getRemainingArgs();
if(args.length != 2){
System.err.println("Usage:seg.SegmentTool <input> <output>");
System.exit(2);
}
Job job = new Job(conf,"nseg.jar");
FileSystem fs = FileSystem.get(conf);
if(fs.exists(new Path(args[1])))
fs.delete(new Path(args[1]),true);
job.setJarByClass(SegmentTool.class);
job.setMapperClass(SegmentMapper.class);
job.setCombinerClass(SegReducer.class);
job.setReducerClass(SegReducer.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
return job.waitForCompletion(true) ? 0 : 1;
}
public static class SegmentMapper extends Mapper<LongWritable,Text,Text,IntWritable>{
private IKSegmenter iks = new IKSegmenter(true);
private Text word = new Text();
private final static IntWritable one = new IntWritable(1);
public void map(LongWritable key,Text value,Context context) throws IOException, InterruptedException{
String line = value.toString().trim();
String[] str = line.split("\t");
for(int i=1;i<str.length;i+=2){
String tmp = str[i];
if(tmp.startsWith("http"))
continue;
List<String> list = segment(tmp);
for(String s : list){
word.set(s);
context.write(word, one);
}
}
}
private List<String> segment(String str) throws IOException{
byte[] byt = str.getBytes();
InputStream is = new ByteArrayInputStream(byt);
Reader reader = new InputStreamReader(is);
iks.reset(reader);
Lexeme lexeme;
List<String> list = new ArrayList<String>();
while((lexeme = iks.next()) != null){
String text = lexeme.getLexemeText();
list.add(text);
}
return list;
}
}
public static class SegReducer extends Reducer<Text,IntWritable,Text,IntWritable>{
private IntWritable result = new IntWritable();
public void reduce(Text key,Iterable<IntWritable> values,Context context) throws IOException, InterruptedException{
int sum = 0;
for(IntWritable val : values)
sum += val.get();
result.set(sum);
context.write(key, result);
}
}
}</span>
打包后，执行命令：yarn jar seg.jar seg.SegmentTool /test/user/zhf/input /test/user/zhf/output
输出结果如下：
<span style="font-size:18px;">阿迪达斯 1 附近 2 陈 22 陈乔恩 1 陈奕迅 1 陈毅 2 限额 4 陕西 4 除个别 1 隐私 1 隔壁 1 集成 4 集锦 1 雨中 2 雪 5 露 1 青 7 青岛 2</span>
但是并没有排序，如果数据量比较小，可以采用linux命令：sort -k2 -n -r kw_result.txt > kw_freq.txt进行排序。
数据量大的话，可以将结果导入Hive，因为只有两列了，hive -e "select key,count from kw_table sort by count desc;" > kw_freq.txt 即可得到有序的结果。
亦可以将之前的ouput作为下一个job的input,实现排序。需要反转map输出的key和value。
代码如下：
<span style="font-size:14px;">package seg;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FileSystem;
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.io.WritableComparator;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
/**
* @author zhf
* @email zhf.thu@gmail.com
* @version 创建时间：2014年8月16日 下午4:51:00
*/
public class SortByFrequency extends Configured implements Tool{
public static void main(String[] args) throws Exception {
int exitCode = ToolRunner.run(new SortByFrequency(), args);
System.exit(exitCode);
}
@Override
public int run(String[] arg0) throws Exception {
Configuration conf = new Configuration();
String[] args = new GenericOptionsParser(conf,arg0).getRemainingArgs();
if(args.length != 2){
System.err.println("Usage:seg.SortByFrequency <input> <output>");
System.exit(2);
}
Job job = new Job(conf,"nseg.jar");
FileSystem fs = FileSystem.get(conf);
if(fs.exists(new Path(args[1])))
fs.delete(new Path(args[1]),true);
job.setJarByClass(SortByFrequency.class);
job.setMapperClass(SortMapper.class);
job.setReducerClass(SortReducer.class);
job.setSortComparatorClass(DescComparator.class);
job.setMapOutputKeyClass(IntWritable.class);
job.setMapOutputValueClass(Text.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
return job.waitForCompletion(true) ? 0 : 1;
}
public static class SortMapper extends Mapper<LongWritable,Text,IntWritable,Text>{
public void map(LongWritable key,Text value,Context context) throws IOException, InterruptedException{
String str[] = value.toString().split("\t");
context.write(new IntWritable(Integer.valueOf(str[1])), new Text(str[0]));
}
}
public static class SortReducer extends Reducer<IntWritable,Text,Text,IntWritable>{
private Text result = new Text();
public void reduce(IntWritable key,Iterable<Text> values,Context context) throws IOException, InterruptedException{
for(Text val : values){
result.set(val);
context.write(result, key);
}
}
}
public static class DescComparator extends WritableComparator{
protected DescComparator() {
super(IntWritable.class,true);
}
@Override
public int compare(byte[] arg0, int arg1, int arg2, byte[] arg3,
int arg4, int arg5) {
return -super.compare(arg0, arg1, arg2, arg3, arg4, arg5);
}
@Override
public int compare(Object a,Object b){
return -super.compare(a, b);
}
}
}</span>
的 175 上海 158 上 85 都市 76 在 71 ppt 64 运输 58 电视 58 式 58 2 52
hadoop中文分词、词频统计及排序,布布扣,bubuko.com
原文地址：http://blog.csdn.net/laozhaokun/article/details/38614765
