/
NGramAggregator.java
89 lines (77 loc) · 3.19 KB
/
NGramAggregator.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
/* LanguageTool, a natural language style checker
* Copyright (C) 2015 Daniel Naber (http://www.danielnaber.de)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
* USA
*/
package org.languagetool.dev.hadoop;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
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 java.io.IOException;
/**
* Aggregate Google ngram data (http://storage.googleapis.com/books/ngrams/books/datasetsv2.html)
* in Hadoop. Based on the Hadoop word counter example.
*/
public final class NGramAggregator {
private static final int MIN_YEAR = 1910;
private NGramAggregator() {
}
public static class TokenizerMapper extends Mapper<Object, Text, Text, LongWritable> {
private final Text word = new Text();
private final LongWritable count = new LongWritable();
@Override
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
String[] parts = value.toString().split("\t");
int year = Integer.parseInt(parts[1]);
if (year >= MIN_YEAR) {
word.set(parts[0]);
count.set(Long.parseLong(parts[2]));
context.write(word, count);
}
}
}
public static class LongSumReducer extends Reducer<Text, LongWritable, Text, LongWritable> {
private final LongWritable result = new LongWritable();
@Override
public void reduce(Text key, Iterable<LongWritable> values, Context context) throws IOException, InterruptedException {
long sum = 0;
for (LongWritable val : values) {
sum += val.get();
}
result.set(sum);
context.write(key, result);
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = Job.getInstance(conf, "Google ngram aggregator");
job.setJarByClass(NGramAggregator.class);
job.setMapperClass(TokenizerMapper.class);
job.setCombinerClass(LongSumReducer.class);
job.setReducerClass(LongSumReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(LongWritable.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}