Hadoop最大值整数算法介绍
发布时间：2021-11-19 18:04:34 所属栏目：教程 来源：互联网
导读：Linux系统CentOS 6.3(64bit) Hadoop1.1.2 Linux下Eclipse版本 最大值算法代码： package yunSave; import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.Path
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Linux系统CentOS 6.3(64bit) Hadoop1.1.2 Linux下Eclipse版本 最大值算法代码： package yunSave; import java.io.IOException; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.IntWritable; 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.input.TextInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; //求最大值 public class MaxValue extends Configured implements Tool { public static class MapClass extends Mapper<LongWritable, Text, IntWritable, IntWritable> { private int maxNum = 0; public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { String[] str = value.toString().split(" "); try {// 对于非数字字符我们忽略掉 for(int i=0;i<str.length;i++){ int temp = Integer.parseInt(str[i]); if (temp > maxNum) { maxNum = temp; } } } catch (NumberFormatException e) { } } @Override protected void cleanup(Context context) throws IOException, InterruptedException { context.write(new IntWritable(maxNum), new IntWritable(maxNum)); } } public static class Reduce extends Reducer<IntWritable, IntWritable, IntWritable, IntWritable> { private int maxNum = 0; public void reduce(IntWritable key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { for (IntWritable val : values) { if ( val.get() > maxNum) { maxNum = val.get(); } } } @Override protected void cleanup(Context context) throws IOException, InterruptedException { context.write(new IntWritable(maxNum), new IntWritable(maxNum)); } } public int run(String[] args) throws Exception { Configuration conf = getConf(); Job job = new Job(conf, "MaxNum"); job.setJarByClass(MaxValue.class); FileInputFormat.setInputPaths(job, new Path(args[0])); FileOutputFormat.setOutputPath(job, new Path(args[1])); job.setMapperClass(MapClass.class); job.setCombinerClass(Reduce.class); job.setReducerClass(Reduce.class); job.setInputFormatClass(TextInputFormat.class); job.setOutputFormatClass(TextOutputFormat.class); job.setOutputKeyClass(IntWritable.class); job.setOutputValueClass(IntWritable.class); System.exit(job.waitForCompletion(true) ? 0 : 1); return 0; } public static void main(String[] args) throws Exception { long start = System.nanoTime(); int res = ToolRunner.run(new Configuration(), new MaxValue(), args); System.out.println(System.nanoTime()-start); System.exit(res); } } 输入的文件内容： [work@master ~]$ hadoop fs -cat input_20141107/555.txt Warning: $HADOOP_HOME is deprecated. 1 5 10 9999 [work@master ~]$ [work@master ~]$ hadoop fs -cat input_20141107/666.txt Warning: $HADOOP_HOME is deprecated. 111 222 333 888 [work@master ~]$ Eclipse的执行画面： 1.Argument参数 program Arguments： hdfs://master:9000/user/work/input_20141107 hdfs://master:9000/user/work/output_20141107 VM Arguments： -Xms512m -Xmx1024m -XX:MaxPermSize=256m 点击Run之后产生下面的结果 运行结果： [work@master ~]$ hadoop fs -cat output_20141107/part-r-00000 Warning: $HADOOP_HOME is deprecated.  （编辑：我爱故事小小网_铜陵站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
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