统计一行一行的数据 每行有两个关键字 mapreduce怎么写
时间: 2023-09-18 15:08:36 浏览: 51
可以使用Hadoop MapReduce框架来统计一行一行的数据中包含多少个关键字,以下是一个简单的示例代码:
```java
public class KeywordCount {
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
String line = value.toString();
if (line.contains("mapreduce")) {
word.set("mapreduce");
context.write(word, one);
}
if (line.contains("怎么写")) {
word.set("怎么写");
context.write(word, one);
}
}
}
public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
context.write(key, new IntWritable(sum));
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = Job.getInstance(conf, "KeywordCount");
job.setJarByClass(KeywordCount.class);
job.setMapperClass(Map.class);
job.setCombinerClass(Reduce.class);
job.setReducerClass(Reduce.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}
```
以上代码中,我们定义了一个Map类和一个Reduce类,Map类用于将每行数据中包含的关键字进行计数,Reduce类用于对每个关键字的计数结果进行汇总。在main函数中,我们指定了输入和输出路径,并提交了任务到Hadoop集群中执行。
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