共同出现的单词(Word co-occurrence)是指在一个句子中相邻的两个单词。每一个相邻的单词就是一个Co-Occurrence对。
Sample Input:
a b cc, c d d c
I Love U.
dd ee f g s sa dew ad da
So shaken as we are, so wan with care.
Find we a time for frighted peace to pant.
And breathe short-winded accents of new broil.
To be commenced in strands afar remote.
I Love U U love i.
i i i i
Sample Output:
a:b 1
a:time1
a:we1
accents:of1
accents:short-winded1
ad:da1
ad:dew1
afar:remote1
afar:strands1
and:breathe1
are:so1
are:we1
as:shaken1
as:we1
b:cc1
be:commenced1
be:to1
breathe:short-winded1
broil:new1
c:cc1
c:d2
care:with1
commenced:in1
d:d1
dd:ee1
dew:sa1
ee:f1
f:g1
find:we1
for:frighted1
for:time1
frighted:peace1
g:s1
i:i3
i:love3
in:strands1
love:u3
new:of1
pant:to1
peace:to1
s:sa1
shaken:so1
so:wan1
u:u1
wan:with1
Code:
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.StringTokenizer; import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Partitioner;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.util.GenericOptionsParser; public class CoOccurrence { public static class TextPair implements WritableComparable<TextPair> {
private Text first;
private Text second; public TextPair(){
set(new Text(), new Text());
}
public TextPair(String left, String right) {
set(new Text(left), new Text(right));
}
public TextPair(Text left, Text right) {
set(left, right);
} public void set(Text left, Text right){
String l = left.toString();
String r = right.toString();
int cmp = l.compareTo(r);
if(cmp <= 0){
this.first = left;
this.second = right;
}else{
this.first = right;
this.second = left;
}
} public Text getFirst() {
return first;
}
public Text getSecond() {
return second;
} @Override
public void readFields(DataInput in) throws IOException {
first.readFields(in);
second.readFields(in);
}
@Override
public void write(DataOutput out) throws IOException {
first.write(out);
second.write(out);
}
@Override
public int hashCode() {
return first.hashCode() * 163 + second.hashCode();//May be some trouble here. why 163? sometimes 157
}
@Override
public boolean equals(Object o) {
if (o instanceof TextPair) {
TextPair tp = (TextPair) o;
return first.equals(tp.first) && second.equals(tp.second);
}
return false;
}
@Override
public String toString(){
return first + ":" + second;
}
@Override
public int compareTo(TextPair tp) {
int cmp = first.compareTo(tp.first);
if(cmp != 0)
return cmp;
return second.compareTo(tp.second);
} // A Comparator that com.pares serialized StringPair.
public static class Comparator extends WritableComparator {
private static final Text.Comparator TEXT_COMPARATOR = new Text.Comparator();
public Comparator() {
super(TextPair.class);
}
@Override
public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2){
try {
int firstl1 = WritableUtils.decodeVIntSize(b1[s1]) + readVInt(b1, s1);
int firstl2 = WritableUtils.decodeVIntSize(b2[s2]) + readVInt(b2, s2);
int cmp = TEXT_COMPARATOR.compare(b1, s1, firstl1, b2, s2, firstl2);
if(cmp != 0)
return cmp;
return TEXT_COMPARATOR.compare(b1, s1 + firstl1, l1 - firstl1,
b2, s2 + firstl2, l1 - firstl2);
}catch (IOException e) {
throw new IllegalArgumentException(e);
}
}
}//End of Comparator
static { // register this comparator
WritableComparator.define(TextPair.class, new Comparator());
} // Compare only the first part of the pair, so that reduce is called once for each value of the first part.
public static class FirstComparator extends WritableComparator {
private static final Text.Comparator TEXT_COMPARATOR = new Text.Comparator();
public FirstComparator() {
super(TextPair.class);
}
@Override
public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2){
try {
int firstl1 = WritableUtils.decodeVIntSize(b1[s1]) + readVInt(b1, s1);
int firstl2 = WritableUtils.decodeVIntSize(b2[s2]) + readVInt(b2, s2);
return TEXT_COMPARATOR.compare(b1, s1, firstl1, b2, s2, firstl2);
}catch (IOException e) {
throw new IllegalArgumentException(e);
}
}
/*
@Override
public int compare(WritableComparator a, WritableComparator b) {
if(a instanceof TextPair && b instanceof TextPair)
return ((TextPair)a).first.compareTo(((TextPair)b).first);
return super.compare(a, b);
}*/
}//End of FirstComparator
}//End of TextPair //Partition based on the first part of the pair.
public static class FirstPartitioner extends Partitioner<TextPair,IntWritable>{
@Override
public int getPartition(TextPair key, IntWritable value, int numPartitions) {
return Math.abs(key.getFirst().toString().indexOf(0) * 127) % numPartitions;//May be some trouble here.
}
}//End of FirstPartitioner public static class MyMapper extends Mapper<LongWritable, Text, TextPair, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private static Text word0 = new Text();
private static Text word1 = new Text();
private String pattern = "[^a-zA-Z0-9-']"; @Override
public void map(LongWritable inKey, Text inValue, Context context)throws IOException, InterruptedException {
String line = inValue.toString();
line = line.replaceAll(pattern, " ");
line = line.toLowerCase();
String[] str = line.split(" +");
for(int i=0; i< str.length-1; i++)
{
word0.set(str[i]);
word1.set(str[i+1]);
TextPair pair = new TextPair(word0, word1);
context.write(pair, one);
}
}
}//End of MapClass
public static class MyReducer extends Reducer<TextPair, IntWritable, TextPair, IntWritable> {
private IntWritable result = new IntWritable(); @Override
public void reduce(TextPair inKey, Iterable<IntWritable> inValues, Context context) throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : inValues) {
sum += val.get();
}
result.set(sum);
context.write(inKey, result);
}
}//End of MyReducer public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
//conf.set("Hadoop.job.ugi", "sunguoli,cs402");
String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
//if (otherArgs.length != 2) {
// System.err.println("Usage: CoOccurrence <in> <out>");
// System.exit(2);
//}
Job job = new Job(conf, "Co-Occurrence");
job.setJarByClass(CoOccurrence.class); job.setMapperClass(MyMapper.class);
job.setMapOutputKeyClass(TextPair.class);
job.setMapOutputValueClass(IntWritable.class); job.setCombinerClass(MyReducer.class); // group and partition by the first int in the pair
//job.setPartitionerClass(FirstPartitioner.class);
//job.setGroupingComparatorClass(FirstGroupingComparator.class); // the reduce output is Text, IntWritable
job.setReducerClass(MyReducer.class);
job.setOutputKeyClass(TextPair.class);
job.setOutputValueClass(IntWritable.class); //FileInputFormat.addInputPath(job, new Path("../shakespeareinput"));
//FileOutputFormat.setOutputPath(job, new Path("output"));
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}//End of main
}//End of CoOccurrence